The importance of water changes

[gbr]

Hi,

I'll present my questions first but there is some background below that may influence an answer.

[1] Why are water changes important?
[2] What are the implications of not doing water changes?
[3] Are water changes more important in a high-tech aquarium (CO2 injection + ferts.) VS a low-tech aquarium (no CO2 injection no ferts)?
[4] How much water should be changed?
[5] How often should changes be done?


Background: I'm new to planted aquariums. I've got a few small planted tanks (10gal) which are low tech. The plants grow slowly but are doing very well. Fish are happy and breeding. I only change 50% of the water when I clean the filter which is once every 2 months or so. I don't use ferts at all. I prune some of the plants every couple of weeks.

I recently purchased a large setup (4' x 2' x 2') ~120gal with CO2 injection. It's well stocked with plants. Plants are doing very well already after weeks (except for the HC which I think just needs more light because it's a deep tank). I use a JBL ferts ... but I'm not comfortable with my knowledge of ferts yet (i'm learning).

After reading Diana Walstead, Ecology of the planted aquarium" I was surprised that she sometimes only changes water every 6 months.

My 120gal tank has been running for a 2 weeks, I've not done any water changes yet. Is this a bad thing? See questions above.

thanks for the help
gbr

 

[aquabillpers]

The role of water changes depends on whether one has a low tech or a high tech aquarium.

As Ms. Walstad observed, water changes are discouraged in low tech tanks, in part because they can be a source of extra nutrients which can upset the balance in those environments. They also are not needed.

In high tech tanks to which chemicals are added to fertilize the plants, frequent water changes are necessary to prevent the buildup of undesirable levels of those chemicals. They tend to be overdosed, since it isn't really known how much of them the plants actually need.

For high tech tanks, a 30% to 50% weekly water change is usually recommended.

Good luck!

Bill

 

[ceg4048]

The role of water changes depends on whether one has a low tech or a high tech aquarium.

As Ms. Walstad observed, water changes are discouraged in low tech tanks, in part because they can be a source of extra nutrients which can upset the balance in those environments. They also are not needed.

In high tech tanks to which chemicals are added to fertilize the plants, frequent water changes are necessary to prevent the buildup of undesirable levels of those chemicals. They tend to be overdosed, since it isn't really known how much of them the plants actually need.

For high tech tanks, a 30% to 50% weekly water change is usually recommended.

Good luck!

Bill

Hi Bill,
I'm afraid I have to disagree with the reasoning. Water changes in a low tech non-injected tank upsets the balance of CO2. Algae respond much more quickly to the introduction of CO2 than the plants are capable of, so water changes are discouraged. The addition of nutrients are irrelevant since algae do not respond to nutrient fluctuations. This is not one of their triggers.

In a high light injected tank the rate of metabolism increases significantly. Again, the buildup of nutrients in the water column does in no way affect the behavior of algae, however, there is a much higher organic waste production rate. Organic waste tends to breakdown into NH4 as it decays so water changes are necessary to remove the waste, algal spores and any accrued NH4. Algae blooms due to high light + NH4 so water changes help to prevent buildup of NH4. This has nothing to do with nutrient level buildup.

The implication of not doing water changes in a high light tank therefore are that organic waste buildup gives rise to higher and higher NH4 concentration levels, which although is process by bacteria, stimulates the algal spores under the bright lights.

The more water is changed and the more frequently the changes are performed, the cleaner the tank and the better the tank is able to deal with mistakes and to suppress algal blooms. In natural systems such as lakes and rivers the immense quantity of water or the constant replacement of water via flow prevents the local NH4 concentration levels from rising sufficiently to trigger blooms. In our high light tanks, which have very small volumes and is a closed system the water changes are necessary to remove the waste.

In a low tech tank water changes do not need to be done but perhaps twice a year since the rate of metabolism is slow (and the organic waste production low) the plants can recycle the organic waste buildup easily.

Cheers,

 

[Mooner]

The addition of nutrients are irrelevant since algae do not respond to nutrient fluctuations. This is not one of their triggers.

Well, as long as we are disagreeing, CO2 is a nutrient, just like Macs or Mics. It is added to modify the growth of our plants. And if algae is not triggered by fluctuations of nutrients then why is it prescribed that BGA can be combated with KNO3? or GSA and PO4 are connected? Not saying that NH4 isn't a culprit, but it isn't by any means the only cause.

In a high light injected tank the rate of metabolism increases significantly. Again, the buildup of nutrients in the water column does in no way affect the behavior of algae

Really?

Organic waste tends to breakdown into NH4 as it decays so water changes are necessary to remove the waste

Agreed concerning organics to NH4, but most NH4 if not all is used up in a well planted aquarium and is not the reason behind water changes. Proper use and maintenance of filters will deal with organic waste + water changes.

Algae blooms due to high light + NH4 so water changes help to prevent buildup of NH4. This has nothing to do with nutrient level buildup.

WC's have everything to due with the build up of nutrients. This is the whole reasoning behind EI. It is the nutrients we add to our aquariums KNO3, KH2PO4, K2SO4, Traces that are not allowed to buildup (ie water changes) but are in sufficient quantity to not cause any limitations. In a stable aquarium NH4 is not an issue.

The implication of not doing water changes in a high light tank therefore are that organic waste buildup gives rise to higher and higher NH4 concentration levels, which although is process by bacteria, stimulates the algal spores under the bright lights.

NH4 is quickly converted to NO3 and is used up. IME it doesn't keep building, again in a well planted tank with a reasonable fish load.

The more water is changed and the more frequently the changes are performed, the cleaner the tank and the better the tank is able to deal with mistakes and to suppress algal blooms. In natural systems such as lakes and rivers the immense quantity of water or the constant replacement of water via flow prevents the local NH4 concentration levels from rising sufficiently to trigger blooms. In our high light tanks, which have very small volumes and is a closed system the water changes are necessary to remove the waste.

Agreed that water changes make for a cleaner tank and inject even more CO2 than we possibly can using other methods. If NH4 was this big of a problem, then wouldn't adding KNO3 be a bad idea? But in EI using NPK is done by many with great success. This is because NH4 is converted quickly and used in a well planted tank. Then more is needed (NPK) to maintain growth.

In a low tech tank water changes do not need to be done but perhaps twice a year since the rate of metabolism is slow (and the organic waste production low) the plants can recycle the organic waste buildup easily.

NPK can still be added to non-carbon tanks without issue. Topped of with plain tap water and go many months between WC's. Some choose to use amendments in the substrate and this works well also.

 

[aquabillpers]

I'm afraid I have to disagree with the reasoning. Water changes in a low tech non-injected tank upsets the balance of CO2. Algae respond much more quickly to the introduction of CO2 than the plants are capable of, so water changes are discouraged. The addition of nutrients are irrelevant since algae do not respond to nutrient fluctuations. This is not one of their triggers.

CO2 is generally considered to be a nutrient. Adding water that has that nutrient in it, as well as others, does destabilize a low tech tank, which is why it should not done very often. We agree, I think.

I believe that NH4 is a much more powerful stimulant to algae than CO2, but I'll leave that to the experts.

BTW, not all water contains CO2. The water from my 150 foot deep well has none.

Bill

 

[ceg4048]

Well, as long as we are disagreeing, CO2 is a nutrient, just like Macs or Mics. It is added to modify the growth of our plants. And if algae is not triggered by fluctuations of nutrients then why is it prescribed that BGA can be combated with KNO3? or GSA and PO4 are connected? Not saying that NH4 isn't a culprit, but it isn't by any means the only cause.

It's probably best to clarify the difference between "buildup" and fluctuation. Also, it's necessary to understand the mechanism by which fluctuating CO2 causes algae. One can have massive quantities of NO3 (buildup) and this will in no way "cause" an BGA bloom. One can also vary the concentration levels of NO3 (fluctuation) and again, no BGA will occur. However, if the concentration of NO3 falls below some level for the lighting conditions this will induce BGA. Whether the concentration fluctuates around this low level or is stable below this level will make no difference. Once the minimum required level of NO3 concentration is breeched the plants suffer and BGA attacks. The same mechanism exists for all other nutrients and their associated algae types. Massive levels of any macro, PO4, K NO3 cannot cause algae. Massive levels of micros, Fe, Mg, you name it, cannot cause algae, whether the levels fluctuate or not. This is Barr's fundamental principle and this is why EI works, because you can be completely over the top with nutrients and this will never cause blooms.

CO2 is a different story because it's uptake mechanism and it's role in photosynthesis is different. Again, high or very high (yet stable) levels of CO2 cannot cause an algal bloom. varying levels of CO2 or low levels do cause algae because the Rubisco enzyme production is tightly linked to to the ambient CO2 level. Rubisco is the transport mechanism for CO2 and RUBP (Ribulose bi-phosphate) which are both used in the Calvin cycle. This is a fundamental requirement of photosynthesis.

Effectively, a shortage of Rubisco directly results in a shortage of photosynthesis. This is an expensive enzyme to manufacture and it takes time. If the ambient CO2 level drops the plant attempts to adjust by reducing Rubisco production. This could take as much as several weeks. If the ambient CO2 levels rise then more Rubisco must be produced. Each change in CO2 level requires a reconfiguration of the Rubisco level and during this time the plant suffers since it has difficulty matching Rubisco levels to CO2 levels for transport and carbon fixation. This weakens the plant, while algae are quick to adjust to the varying levels of CO2.

So fluctuating and/or low levels of CO2 directly impact food production, while macro/micro fluctuations have no impact as long as the minimum level is above that required for the current lighting level. The transport and catalyst mechanisms for macro/micro are not linked to concentration levels in the same way as is CO2.

Each time a plant is stressed by nutrient starvation structural damage and decay occurs which then leeches NH4 and other products such as carbohydrates and nutrients into the water column. Under high lighting the algal spores respond to the NH4 level changes and then bloom.

In a high light injected tank the rate of metabolism increases significantly. Again, the buildup of nutrients in the water column does in no way affect the behavior of algae

Really?

Yes, really. Again, this is fundamental. Have you not been reading the Barr Report Newsletters? Check the Nitrogen newsletter as well as the Phosphorous Newsletter. What many suffer from is a case of optical illusion. NH4 can be in the water column at the same time as nutrients The spores are triggered to bloom via light and NH4. Having then bloomed the algae will feed on whatever nutrients are in the water column so it appears as if nutrients caused algae. We need to be clear on this issue. There is a difference between causality and reaction. Nutrients cannot cause algal spores to bloom into the forms we are terrorized by. Algal spores do not care what the levels of nutrients are. They only care about the NH4 level and the light level. Plants care much more about the nutrient level. If the level is too low for the lighting condition they cannot uptake the quantity of nutrients required at the speed necessary. They become unhealthy and leech NH4. Algae then attacks. Allow me to demonstrate:

I dose 2 to 3 times the suggested EI levels. That level is equivalent to the so called buildup level. Typical phosphate levels are 7-9 ppm. After a water change I immediately dose back up to the 7-9ppm so the tank always has high PO4 levels. Unfortunately this tank always runs low on PO4 first if left unattended. I left town for about 5 days and forgot to dose extra as well as to lower the light. When I returned the tank was covered in GSA. I immediately did a water change and dosed my typical high levels. The photograph below shows leaves damaged by GSA and new growth on the same plant. See if you can tell which of the leaves is associated with LOW PO4 and which are associated with high PO4 buildup.

Organic waste tends to breakdown into NH4 as it decays so water changes are necessary to remove the waste

Agreed concerning organics to NH4, but most NH4 if not all is used up in a well planted aquarium and is not the reason behind water changes. Proper use and maintenance of filters will deal with organic waste + water changes.

Well, this is another illusion. I like Tom's analogy of the elephant and the mouse. The plants are the elephants and they require massive amounts of food. Mice on the other hand don't require much at all in comparison. Therefore, very small levels of NH4, lower levels than can be detected by your NH4 test kit, can trigger algal blooms. Why do you think that maintenance of filters helps? When you remove the detritus in the filter you are removing a source of NH4 production that the filter bacteria are not capable of removing in one go. Low levels of ammonia find it's way back into the tank and in the presence of light triggers algal blooms, most often BGA.

Why do you think Tom suggests multiple water changes (2X to 3X per week) with a new tank setup? NH4 buildup. Not enough attention is paid to NH4 because everyone is completely paranoid about nutrients.

Algae blooms due to high light + NH4 so water changes help to prevent buildup of NH4. This has nothing to do with nutrient level buildup..

WC's have everything to due with the build up of nutrients. This is the whole reasoning behind EI. It is the nutrients we add to our aquariums KNO3, KH2PO4, K2SO4, Traces that are not allowed to buildup (ie water changes) but are in sufficient quantity to not cause any limitations. In a stable aquarium NH4 is not an issue..

Forgive me if this seems rude, but it appears you have completely missed the point of EI. Nothing could be further from the truth. The point of EI is exactly to provide an excess of nutrients in order to ensure that the nutrient levels never fall below the required levels. I can and do dump as much nutrients as I want in my tank and I don't have algae. When I'm not home and the nutrient levels fall below the required amount I get algae as demonstrated above. It's easy to get rid of though; just, clean the tank and dose massive quantities. Nutrients don't cause algae.

The implication of not doing water changes in a high light tank therefore are that organic waste buildup gives rise to higher and higher NH4 concentration levels, which although is process by bacteria, stimulates the algal spores under the bright lights.

NH4 is quickly converted to NO3 and is used up. IME it doesn't keep building, again in a well planted tank with a reasonable fish load.

Again, we are not talking about levels of ammonia detectable by your test kit. If your plants are starving you will get local NH4 rise at the surface of the leaf. This is specifically why the algae attacks the leaf surface, because of leeching NH4 and nutrients.

The more water is changed and the more frequently the changes are performed, the cleaner the tank and the better the tank is able to deal with mistakes and to suppress algal blooms. In natural systems such as lakes and rivers the immense quantity of water or the constant replacement of water via flow prevents the local NH4 concentration levels from rising sufficiently to trigger blooms. In our high light tanks, which have very small volumes and is a closed system the water changes are necessary to remove the waste.

Agreed that water changes make for a cleaner tank and inject even more CO2 than we possibly can using other methods. If NH4 was this big of a problem, then wouldn't adding KNO3 be a bad idea? But in EI using NPK is done by many with great success. This is because NH4 is converted quickly and used in a well planted tank. Then more is needed (NPK) to maintain growth.

NH4 and KNO3 are completely different molecules. You can't compare one with the other. One is toxic and the other innocuous. NH4 is higher in nitrogen by molar weight. Some do use Urea but this is playing with fire. NH4 causes algae NO3 does not. Definitely should check the Nitrogen newsletter.

Cheers,

 

[VaughnH]

Tweet!! (Referee whistle) You are both right. We do big water changes when we dose per EI in order to avoid really big buildups of one or more nutrients, to where some fish may be affected. But, those who do not do the EI overdosing of nutrients still benefit from regular big water changes, at least partly because that removes dissolved organic compounds which can be harmful to the fish. Walstad type tanks just do everything in slow motion, so regular big water changes are unnecessary, and they may add CO2, which may start algae growing, since it is only a temporary addition of CO2. If that same amount of CO2 were added consistently, every day, Walstad tanks would benefit too.

 

[ceg4048]

Hoppy,
If the only reason you were doing a water change in an EI tank was to avoid buildup of nutrients wouldn't it be more sensible to simply stop dosing for a while? That would allow nutrient uptake to reverse the buildup. After a while one could resume dosing.

What I'm trying to say is that if one focuses too much on nutrient buildup then one misses the boat. There are links given by Tom showing studies which conclude that extremely high nutrient levels have no effect on fish health.

Organic waste production in a highly lit tank makes the tank susceptible to "mini" NH4 ammonia spikes which triggers algal blooms since algae react quickly to the combination of NH4 rise and high light. Water changes remove organic waste, NH4 as well as the algae and algal spores themselves. So water changes are important in a high light tank regardless of the dosing scheme. More nutrients mean more growth and more waste so that water changes in an EI tank as opposed to say, a PMDD or a PPS tank are more important are perhaps more critical, but not because of nutrient buildup, but instead due to higher waste production.

Of course, resetting the tank via water change then makes it easier to stabilize the dosing scheme so that no additional calculations are necessary, just continue the same dosing pattern. This is therefore a convenience of the water change as it accomplishes cleaning and resetting in one go.

I've run EI tanks at 60-70 ppm NO3 and 10 ppm PO4 for years and in that tank have bred several consecutive generations of dwarf chiclids. I've also had the same conditions in the tank with Discus. No harm whatsoever. The Discus growth rate wasn't great but I attribute that to my not feeding them 8 times per day. These tanks have all been pristine.

We really need to get over our nutrient paranoia otherwise we will continue to have algae problems. In fact the only thing that stops me from dumping more nutrients into the tank is cost and the tedium of pruning associated with absurd growth rates.

Cheers,

 

[VaughnH]

I'm not the least paranoid about nutrients, other than shortages of nutrients. And, that causes me to wonder why, if you fiind pruning associated with absurd growth rates to be tedious, you don't just reduce the light intensity. It is the light intensity that determines the growth rate. Adding more nutrients to a lower light tank doesn't result in significant increases in growth. But, trying to slow the plant growth by restricting nutrients can lead to unhealthy plants, especially when some of the plants in the tank are less "competitive" than others.

As I said, I think regular water changes are beneficial to all aquariums where CO2 is being added, no matter what fertilizing method is being used. But, for EI dosed tanks, those water changes allow us to be very casual about how much we dose, thus the recommended amounts to dose are the same for both 10 and 20 gallon tanks.

I use a continuous water change system, so I never will see a buildup of any nutrient, making my dosing even less critical. I would almost have to spill a fertilizer in the tank to run into problems from excessive dosing. Also, I have been dosing at twice the EI rates for phosphates for a year now, with no observable problems resulting. I have thought of increasing it again just to see if the minimal GSA I get will stop.

 

[ceg4048]

Hi Hoppy,
I did it to prove to myself that nutrients don't cause algae or harm fish, that excess nutrients don't cause algae or harm fish and that nutrient buildup doesn't cause algae or harm fish. Also I love looking at bright tanks.

I've discovered that if you do double EI for the other nutrients and you do triple EI for the PO4 only, the minimal GSA goes away.

Cheers,

 

[VaughnH]

I certainly wouldn't argue with success. So, I will think seriously about increasing my fertilizer dosing again.

Won't nitrates at some level harm fish? I don't know what that level is, but I do know that following EI, even casually, doesn't get you to that level.

 

[aquabillpers]

If the only reason you were doing a water change in an EI tank was to avoid buildup of nutrients wouldn't it be more sensible to simply stop dosing for a while? That would allow nutrient uptake to reverse the buildup. After a while one could resume dosing.

The people who use EI don't know how much of which nutrient their aquariums require. So they overdose everything and then remove the excess via water changes once or twice a week, and then overdose some more.

This works quite well for a lot of people, as far as growing plants is concerned. But it doesn't seem to be a very elegant way to feed plants.

Farmers who raise beef cattle know to the pound how much of what food will produce the "best" growth on their animals. Why can't aquatic plant growers do the same thing?

In a perfect world one would monitor nutrient levels and add more when needed. But EI is easier.

Bill

 

[ceg4048]

I certainly wouldn't argue with success. So, I will think seriously about increasing my fertilizer dosing again.

Won't nitrates at some level harm fish? I don't know what that level is, but I do know that following EI, even casually, doesn't get you to that level.

Hi Hoppy,
Check Tom's article [url]http://www.barrreport.com/articles/3267-no3-nh4-toxicity-test-plants-critters.html[/URL]

Unfortunately (and I could kick myself) the journals that he linked to are no longer free. I did read them but forgot to download them.

If we were keeping trout and salmon in our tanks then this would be an issue, but for our fish the NO3 levels that cause harm are astronomical, somewhere on the order of 400 ppm and higher. We have nothing to fear whatsoever at our dosing levels. It's not even close. This was what I was alluding to when I mentioned the paranoia of nutrients. Nitrates get blamed for everything, stunting, poisoning, you name it, all unjustly. It's the ammonia that happens to be in the water at the same time, being produced by the breakdown of organic waste buildup that does the damage. Nitrates are left with the smoking gun and are convicted based on circumstantial evidence alone.

Now, if I can breed Apistogramma Cacatuoides with a weekly input of 60 ppm inorganic NO3 and 7-10 ppm inorganic PO4 doesn't that tell you something?

Look at this: Do these fish in any way look like they are bummed out about having 60 ppm NO3 being dumped into their habitat every week?
[URL=http://good-times.webshots.com/photo/2490628200038170470JGjgdw] [/URL]

How about these guys? They could care less. What they do care about is clean water free of organic waste buildup.
[URL=http://good-times.webshots.com/photo/2467358850038170470iBvKZa] [/URL]

The people who use EI don't know how much of which nutrient their aquariums require. So they overdose everything and then remove the excess via water changes once or twice a week, and then overdose some more.

This works quite well for a lot of people, as far as growing plants is concerned. But it doesn't seem to be a very elegant way to feed plants.

Farmers who raise beef cattle know to the pound how much of what food will produce the "best" growth on their animals. Why can't aquatic plant growers do the same thing?

In a perfect world one would monitor nutrient levels and add more when needed. But EI is easier.

Hi Bill,
Let me ask you this: Do you know exactly how much food you consume on a daily basis? Would that amount be the same for the next person? Elegance has nothing to do with it. You pick up your plate and put an amount of food that looks about right. You know if the plate is too full or not full enough and that about it. Sometimes, even after having had a full plate you go back for seconds. Is that elegant? Do you care? No. Well neither do you plants. They will eat as much as you can give them and what they don't eat today they will eat tomorrow.

Farmers need to know to the pound because they have to pay a lot of money for tons of fertilizer or tons of grain and therefore profit is at stake. If my livelihood depended on selling my plants then, yes, I would want to know exactly what the minimum level I could get away with or what the maximum necessary for best growth is.
Because I don't care about profit I don't care about exact values.

I don't consider nutrient monitoring to be in any way a "perfect" endeavor. It's tedious and boring. If someone likes to monitor then more power to them but I would rather look at pretty plants with brew in hand and not worry about it.

I'm one of those EI people and I don't do water changes to remove build up of nutrients. If I could do a water change without removing the nutrient buildup I would do it in a heartbeat because that would save me money. In fact, I depend on this buildup because oftentime I leave town. Having a nutrient buildup means not having to worry about dosing if the tank is unattended for a few days.

The water change removes organic waste and other toxic components from my tank. That is much more important than any nutrient buildup.

Cheers,

 

[aquabillpers]

Hi,

The sole point of my post was that EI is not an "elegant" solution to aquatic plant nutrition.

"Elegance" in this context means "scientific exactness and precision." EI certainly works well at growing plants, but it is clearly not "elegant."

Determining the optimum amount of nutrients that one's plants need and dosing to that level would be an "elegant" approach but not practical for most of us.

An alternative to overdosing macros is to learn how much each tank needs to maintain a reasonable level of the nutrients and then to dose to maintain that level.

For example, i have one tank that needs 1/4 tsp of KNO3 every 2 or 3 months to maintain 5 to 10 ppm of nitrate in the water column. I wouldn't call this "elegant" either, but it is closer.

Good luck!

Bill

 

[rich815]

>>>>For example, i have one tank that needs 1/4 tsp of KNO3 every 2 or 3 months to maintain 5 to 10 ppm of nitrate in the water column. I wouldn't call this "elegant" either, but it is closer.

What testing method or kit are you using, or have you used, to determine the 5 to 10 ppm of nitrate in that tank?

 

[aquabillpers]

>>>>For example, i have one tank that needs 1/4 tsp of KNO3 every 2 or 3 months to maintain 5 to 10 ppm of nitrate in the water column. I wouldn't call this "elegant" either, but it is closer.

What testing method or kit are you using, or have you used, to determine the 5 to 10 ppm of nitrate in that tank?

I am using the API nitrate test kit. I have been using that for over 10 years, and up to 20 PPM, it is adequate.

No, I have not "validated" that kit, but reflects accurately the addition of, say, 1/4 tsp of KNO3 in a certain volume of water, for example.

BTW, this is not an endorsement of all API kits.

Bill

 

[Tom Barr]

Hi,

The sole point of my post was that EI is not an "elegant" solution to aquatic plant nutrition.

If you want to mince words.......how about non limiting nutrient supply?
This is how it's referred to in research and studies on plants.

I'm speaking in general, not going after you personally here, I think we agree far more than you/others might realize.

Liebig did pretty well using this concept and then reduced each to test his notions, Shelford used it for the upper range limits and of Hoagalnd made a nifty formula and then most everyone in research uses a Hoagland modified solution, which is "excess" and often the control reference.

So.........I see all this crap on the web about excess, waste and other semantical agenda based manure..............yet the simple concept of a control, an experimental test etc is lost to the Public's own political agenda base perception, not facts, not logic etc..............

This, not the lack of elegance, it the real underlying baloney here.
Then other folks fail to acknowledge CO2 fertilization and adding it to excess levels, often killing fish etc far more than anyone dosing KNO3, but they curiously never mention that aspect.

"Elegance" in this context means "scientific exactness and precision." EI certainly works well at growing plants, but it is clearly not "elegant."

If you made this statement in presentation in the plant dept here, you'd get ripped up. Providing a non limiting control is basic research the 2nd year students understand and are tested on.

So what might be a good limiting control for the other end of this situation?
Use DI water.

Then several solutions that vary in concentration in between the non limiting and the DI water. Then you compare relative growth rates to assess or some other parameter(Dry weight N and P etc), or parts/organs of the plant.

Basic ecology type stuff here and basic ag test that have been done for well over 50+ years.

This ain't new.

Determining the optimum amount of nutrients that one's plants need and dosing to that level would be an "elegant" approach but not practical for most of us.

An alternative to overdosing macros is to learn how much each tank needs to maintain a reasonable level of the nutrients and then to dose to maintain that level.

For example, i have one tank that needs 1/4 tsp of KNO3 every 2 or 3 months to maintain 5 to 10 ppm of nitrate in the water column. I wouldn't call this "elegant" either, but it is closer.

Good luck!

Bill

True, now you at this range in between, neither low nor high.
This need not be done with lots of testing, the plants are pretty good indicators of system health........something many learn over time, then think they know something more about dosing, when they really have just become better at watching the plants and learning more about planted tanks in general.

The other issue with EI or PMDD+PO4 or ADA or any water column dosing is the sediment.

Adding that reduces the demand or the need to watch the water column as closely.

Using plain sand is a control here.
Using a rich delta loam with some added inorganic ferts is a non limiting control(or modified hoaglands for hydroponic plant cultures) and then we test the various sediments we wish to test in between.

I have a post about all that and a Ms Word doc that I did for a class.
5 sediment types and used Water primrose(Ludwigia) as the plant.

I think the rate of growth is also a factor in this as well, a non CO2 tank will do fine at 1 ppm of NO3, whereas a high light CO2 might need 5ppm, or 10ppm to maintain good health(and 10X faster growth) over the same time frame.

So you have much more resiliency at lower light and non CO2 vs the higher rates of growth used in EI or any CO2 enriched method.

I would suggest that all CO2 methods are "not elegant" based on your logic, not just EI, and that the very use of CO2 fertilization is the root of all evil, as it where

However, I also am pragmatic. I like the high rates of growth and like the gardening, I, like many, are sometimes impatient.

Regards,
Tom Barr

 

[tedr108]

I figure that sometime in the future, someone (maybe Tom ) will invent a little electronic device that will monitor your aquarium water with a simple little probe that hangs in the tank or the sump. There will be 2 models of this device: 1) Manual (cheaper) model - When you get up in the morning, the device will tell you exactly how many grams/milliliters of PN, MPP, or micro nutrients to add to your tank, and 2) Automatic (more expensive) version - This one will dose your tank automatically. Until this device is invented (and comes down in price), I'll stick with EI and my water changes. EI is simple, it works, and it's even cheap!

 

[aquabillpers]

I figure that sometime in the future, someone (maybe Tom ) will invent a little electronic device that will monitor your aquarium water with a simple little probe that hangs in the tank or the sump. There will be 2 models of this device: 1) Manual (cheaper) model - When you get up in the morning, the device will tell you exactly how many grams/milliliters of PN, MPP, or micro nutrients to add to your tank, and 2) Automatic (more expensive) version - This one will dose your tank automatically.

LOL! I don't think I would buy such a device, even if Tom etched his autograph into it. Once a newly set-up tank is stable, the only time I test is if it looks like something isn't going right. IMO, this almost always the problem is a lack of nitrates caused by rapid plant growth.

I'll add that while 1 ppm of nitrates might be fine for plants, that can quite quickly drop to zero ppm, which isn't. If one is using EI that isn't too serious, but in a slow growth environment it takes longer for thing to re-stabilize, and while that is going on, algae can flourish.

Until this device is invented (and comes down in price), I'll stick with EI and my water changes. EI is simple, it works, and it's even cheap!

Well, there is another way that is even simpler and cheaper, and works almost as well.

Bill