Why water change day seems to grow aquatic plants better

Matt F.

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Again, streaming is gas rising from a cut or damaged leaf. Don't know how more direct I can be. Pearling occurs at different rates. HC is know to pearl more than other plants post water change. All plants pearl and let off O2. depends on how saturated the water is surrounding the plant. Sometimes you can't see the gas, other times you can. I hope this clarifies it for you.

You did not say that pealing is an indicator of growth, but you're assuming that pearling indicates something, because you're adjusting your GH variable to try to induce it. Pearling is the only visible means you have to observe a change. This is problematic especially after a water change because you are introducing O2 SATURATED WATER (sorry for the caps, just want to be clear). It is clear where you are going: that the change in osmotic pressure increases plant growth (hence the water change connection to better plant health. Your methods needs work, because you're basing your assumption on your observation. We're telling you that many things cause O2 bubbles on plants, pearling, and streaming. The connection you are trying to make between GH booster and the change in osmotic pressure needs some work, especially if you are going to test for it.

Problem: you're using gas bubbles as your guide when trying to induce osmotic response. You're introducing a gas differential when you do the water change!

I'm sorry but there are many holes in your hypothesis that I, along with others, are trying to point out. You have done nothing to try to address the issues we bring up. It's almost like you're so hell bent on distorting reality via semantics that you're just not hearing anyone else.

Trying to help, but it's just not getting anywhere.


Solcielo lawrencia;115724 said:
Streaming is just O2 rising to the surface at metered intervals. It can also occur on non cut stems, as I have just seen from the HC. Also, since I closely matched the amount of GH added, no gas bubbles were formed at the HC, unlike the previous three days. Just some pearling/streaming.

Again, I did NOT say that pearling is an indicator of growth, even though it is as a result of photosynthesis. Please read what I wrote and not what you think I wrote. Just because the word pearling and growth are in the same paragraph does not mean I said pearling results in growth or whatever. This is the third or fourth time I said this.

Anyway, I found the answer to my previous question about tonicity. Yes, even plant cells lyse or crenate due to changes in osmotic pressure.
 
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Matt F.

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You have shown nothing. In this case common sense and experience trumps casual observation and some pictures. There are many variable you are not taking into account. These variables are not under your control yet. therefore there is no science in your claim. It's all conjecture at this point. Please try to reflect that in your statements. Don't come off as though you've proven something or debunked what we are saying.

What you saying (paraphrase) is: if you use less GH booster, YOU get larger bubbles on your plants after a water change. Another problem is see is that you are increasing growth in your tank with water changes without understanding the mechanism. You're exacerbating what we already know to be true (that water changes seem to increase healthy growth and less algae).

Isolate variables and test, retest, and have others test to replicate your findings. I think that's what it's all about?

Solcielo lawrencia;115729 said:
Here are pictures of the pearling over three consecutive days' water changes. Each water change was 90%. I did not take a picture of last nights water change because there was no pearling. Below each picture is how much GH added to the fresh water during the water change. Fertilizers added after the water change include NPK in roughly the same amounts.

View attachment 4550
3/5 tsp of CaSO[SUB]4[/SUB] and 2/5 tsp of MgSO[SUB]4[/SUB]

View attachment 4552
2/5 tsp of CaSO[SUB]4[/SUB] and 1/5 tsp of MgSO[SUB]4[/SUB].
There are even more gas bubbles on the HC.

View attachment 4551
2/5 tsp of CaSO[SUB]4[/SUB] and no MgSO[SUB]4[/SUB]
This last photo shows that the gas bubbles are the largest probably because I added the least amount of GH.

Also, considering that last night's (7/1/13) WC (GH matched closely with the previous days' concentration) had no pearling like the ones seen in these pictures, that pretty much debunks the high gas concentration of tap water forming on the plants.
 
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All I'm saying is that osmotic pressure can force gas out of plants. That's all. This can explain why it appears that plants pearl more after a water change as has been mentioned previously in this thread. I mention this so that you and others can test it to see if you can verify that changing GH of incoming water also has the same results that I'm seeing. It is only in my tank that I see this phenomenon and would like to know if others observe this phenomenon as well. I am not out to prove anything here, but I am out to see if my observations can be replicated by others. I'm also not trying to convince anyone with the hypothesis that it's osmotic pressure that causes plants to grow faster since it's just a hypothesis that needs to be tested. When I have a theory (that is backed by extensive testing) to explain this phenomenon, then I'm trying to convince you.

Also, how can you explain that the last water change induced no visible gas on any of the leaves of HC? Whereas the previous three days all induced gas from it? The only difference I accounted for was GH, matching the previous day's water change. It's the same tap water so the same dissolved gasses should be present.
 

Matt F.

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Hi,

My whole point is that there is a lot going on in our aquariums at any given time. You'd have to control a huge amount of variables in order to infer anything. So far we've had ideas as to what causes the observable increase in plant growth and a reduction in algae. It seems that water changes are correlated with good robust growth and fewer problems with algae, but we don't know the mechanism. Osmotic pressure may be a part of it, but my money is on more than one thing being the cause.

A controlled situation is needed with pure water (distilled) reintroduced with minerals at measured levels. Also account for circulation, which affects gas levels, surface scum, light intensity, species of plant, nutrients, co2, substrate, temperature, organic waste and detritus buildup, aerobic and anaerobic bacteria, just to name a few things to consider. If you can brainstorm all the variable and control for them, then we can test GH's effect on plant growth.

About pearling versus streaming: it's semantics. But using visible gas as any kind of measure is hard to quantify, especially when we're dealing with unknown variables in a system. I guess that's why I went on the attack (not towards you, personally, but your methods).


-Matt




Solcielo lawrencia;115747 said:
All I'm saying is that osmotic pressure can force gas out of plants. That's all. This can explain why it appears that plants pearl more after a water change as has been mentioned previously in this thread. I mention this so that you and others can test it to see if you can verify that changing GH of incoming water also has the same results that I'm seeing. It is only in my tank that I see this phenomenon and would like to know if others observe this phenomenon as well. I am not out to prove anything here, but I am out to see if my observations can be replicated by others. I'm also not trying to convince anyone with the hypothesis that it's osmotic pressure that causes plants to grow faster since it's just a hypothesis that needs to be tested. When I have a theory (that is backed by extensive testing) to explain this phenomenon, then I'm trying to convince you.

Also, how can you explain that the last water change induced no visible gas on any of the leaves of HC? Whereas the previous three days all induced gas from it? The only difference I accounted for was GH, matching the previous day's water change. It's the same tap water so the same dissolved gasses should be present.
 

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Solcielo lawrencia;115747 said:
All I'm saying is that osmotic pressure can force gas out of plants. That's all. This can explain why it appears that plants pearl more after a water change as has been mentioned previously in this thread. I mention this so that you and others can test it to see if you can verify that changing GH of incoming water also has the same results that I'm seeing. It is only in my tank that I see this phenomenon and would like to know if others observe this phenomenon as well. I am not out to prove anything here, but I am out to see if my observations can be replicated by others. I'm also not trying to convince anyone with the hypothesis that it's osmotic pressure that causes plants to grow faster since it's just a hypothesis that needs to be tested. When I have a theory (that is backed by extensive testing) to explain this phenomenon, then I'm trying to convince you.

Also, how can you explain that the last water change induced no visible gas on any of the leaves of HC? Whereas the previous three days all induced gas from it? The only difference I accounted for was GH, matching the previous day's water change. It's the same tap water so the same dissolved gasses should be present.

Inadvertently proving something is not a bad goal either:)

Another way is to see if you can disprove something. Often this will yield more fruit and isolate things more, it may not answer your original question however.
What can we rule out?

A good way to measure real plant growth and the tap water issues with various gases is to use an O2 meter.

Then you have a non destructive method to measure aquatic submersed O2/growth in plants, and we can also measure the tap before and after water changes and the tank to account for O2 contribution from the tap.
This goes pretty quick with an O2 meter.

Pearling is one thing, but I think the real goal is to see why the plants GROW better, not so much pearl more/less.
O2 is actual growth, whereas pearling may or may not be.

But we need to account for the tap water's contribution to the O2.
 
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According to my Random Question: What gas (Hint: oxygen) do fish need to breathe?
Answer: oxygen. And plants need it, too.

So why is it that we don't also inject O2 into our tanks? It's assumed that plants make enough of it but what about at the root system where photosynthesis does not occur so it can't provide itself with the needed oxygen?

The more in depth I get, the more I realize I have no hobbyist way to test anything accurately. I have no lab equipment to check for O2 concentration nor do I have TDS meters. :p

A side question: Does O2 dissolve more readily than CO2?
 

Yo-han

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Plants do release O2 from their roots into the substrate. This way the bacteria in the substrate receive their O2 and break down and produce nutrients for the plants. But I think high oxygen at night (when plants use most O2) is really benificial for plant growth. Since I aerate at night I do feel (can't prove it) plants grow better.
 
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I know that O2 is transported down to the roots but why is it still the case that O2 saturated water grows plants better? Is it because it supports aerobic bacteria and their metabolism helps create nutrients that are easier for plants to absorb?

Do plants grow faster at night or in the day? During the day, plants are actively making sugars. At night, they break down those sugars for energy. However, I've noticed that some plants make larger growth gains during the night, at least in terms of internode length. I wake up in the morning and some Rotala's are taller than before I went to bed.
 

Matt F.

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I also get increased growth and a reduction of algae when doing a 3 day brown out.
Side note, I wonder how surface scum affects gas levels...

Solcielo lawrencia;115902 said:
I know that O2 is transported down to the roots but why is it still the case that O2 saturated water grows plants better? Is it because it supports aerobic bacteria and their metabolism helps create nutrients that are easier for plants to absorb?

Do plants grow faster at night or in the day? During the day, plants are actively making sugars. At night, they break down those sugars for energy. However, I've noticed that some plants make larger growth gains during the night, at least in terms of internode length. I wake up in the morning and some Rotala's are taller than before I went to bed.
 
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Surface scum, as in a biofilm? If it's a biofilm, then it most likely contains obligate aerobic bacteria with some aero-tolerant anaerobes. It will use O2 for respiration so it takes the majority from the atmosphere and some from the water column.

Here's another question: I've been assuming that the pearling from the plants after a water change is O2 gas. Is it really? Or is it stored CO2? The fresh water is low in it, hence the pressure gradient that causes the CO2 to be pulled out. (I assume that tap water is not high in CO2, at least not more than what can be injected.)

If it's stored CO2, then I figure that's where it gets the carbon source to build cellulose at night.
 

Tom Barr

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Measured the O2 before and after the water changes.
I took 4 readings 30 minutes apart and averaged them.

I changed the 180 Gal after 4 hours of the light cycle:

129% O2 at 9.89 ppm and after: 10.18 ppm at 138%
So the tap offered a little bunch in the growth.
9% more O2.

The 120 had about 8.98 (103%), but I took the measure AFTER doing 4 rows of plant trimming/making a sediment mess.
9.81ppm/128% post water change.

I do not think the 120 Gal test is fair, it skews due to the uprooting and sediment.
Still a small bump is growth is noted. This could be due to the plants draping over and then getting fluffed up again which can remove periphyton on leaves.

O2 was not that different for incoming water, it was generally LESS than tank water, which suggest that the plants are growing and giving off a fair amount of O2.
About 9.20-9.40 ppm for the tap water for O2.

This is well above 100%, but...........once the water warms up, then O2 will go back down. The tap comes in maybe at 60-65F, and it's sealed till it comes out of the tap faucet.

So I see the growth bump, but I cannot say WHY the growth increase is there.
Perhaps exposure to the air, and free ample CO2, then follows a nice growth spurt post water change.
Perhaps increase in CO2 from bacterial respiration etc which leads to more plant growth.

Does NOT appear due to dissolve O2.
 

Matt F.

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What about an increase in light. When you lower the water level, you have less between the light source and the plants.
What about dissolved waste? Does this have an effect on light transmission?

I guess what I am asking is does fresh water contain fewer contaminants that could affect light transmission?
 
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Tom Barr

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No, we have a PAR meter, there's a slight difference(1-2%, open tank tanks do not have the crusty old glass lids etc.), but certainly not enough to make a significant effect over the brief time frame.

I am really happy with the dissolved O2 performance of the wet/dry systems and the ample O2 when the plants are growing. I consistently hit 20-40% over saturation on the 180 and the 120 durign the day cycle for most of the photoperiod, the 70 and the ADA 60p are not yet complete.
Once they are, I'll be hitting similar ranges but perhaps a tad less, I estimate 10-20% over.
 

CroANT

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Hello all,

Just read entire thread in one reading, very interesting read! (very boring day on work :D)

I'm newb , just got to growing plants successfully and stopped fearing of algae.
I have the same findings as everybody after water change and it does not matter if you have CO2 or not, pearling happens.

I think it is important to note that second day that effect does not re-apear. (in non CO2 aquarium at least)
So "fresh water" is not anymore so fresh the second day, if it is to say fresh water induces for some reason pearling by its
to us unknown characteristics,concentrations ..whatever which disappears next day or something is added to water by system it self.

So my question no.1 here would be what could have changed so dramatically over night in water column?
You know better than me what could have possibly changed over night and maybe give it a thought?

And no.2 does it matter what % of water being changed, would be great if that could be done with lets say 5% , people would change water everyday ..hmm might try that myself ... anyways good one, note to my self: discover % at which pearling occurs or wait till someone with more time do it :D

So just to add to discussion a look from another angle maybe?
->Plants are living creatures and can sense various things,they can be under stress and they can be in good shape(feel good) as all know.
So along those lines it looks to me like they had a shower
after being dirty/smelly and now feeling sexy as you would after good shower so they thank you with pearling and asking for a kiss :D

Also interesting read on O2 in one point I was wandering why measure O2 why just not try injecting the same as CO2 and look at the plants would be more in the line with EI methodology and easier maybe.

It would still be nice to definitely know why , so I'll leave that to smarter people here to answer it for me so I can copy later :D :D :D
Please do get on the work asap as we all want to know :D :D :D

I think that would be the biggest leap in hobby ever!

P.S. I haven't realized that frequent water changes have that great of an impact on plant growth, maybe it should be mentioned more often(the same as not good CO2lvl) on these forums and noted for newbs like me in original EI someplace, it would surely make it even more popular as more people would be successful in growing plants and not algae , just a thought ..
And idea which came out of writing this post if discovered minimum % of water change to make them pearl would make EI if its not already defacto standard for planted aquariums.

I hope you had good time reading my post as I did writing it.


kind regards,
Kruno
 

Tom Barr

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Solcielo lawrencia;117467 said:
About limed water, the process of liming removes CO2.

"The slaked lime is also an efficient absorber of carbon dioxide, so tapwater treated by "lime/soda" softening generally arrives at the household tap still depleted in CO2, which contributes to its high pH.
http://www.skepticalaquarist.com/municipal-water-softening

So I don't think limed water contributes CO2 in an aquarium.

Lime softening removes almost all the CO2.

They add CO2 to such water in fact, this is to prevent such high pH's, partial lime softening can take care of some of this, but the pH comes out at 10.1, if the tap is 8, then they need to mix a lot to stay within the pH optima for distribution and other downstream processing in the water treatment.
This is done using CO2 gas enrichment. It is generally avoided, but there are times when it's needed and the delivered product is mandated to have a specific Calcium /General hardness/Alkalinity range.


It's only going to occur where your tap is normally very hard and they treat at the treatment plant to reduce the Ca/Mg mostly.
 

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Solcielo lawrencia;117467 said:
About limed water, the process of liming removes CO2.

"The slaked lime is also an efficient absorber of carbon dioxide, so tapwater treated by "lime/soda" softening generally arrives at the household tap still depleted in CO2, which contributes to its high pH.
http://www.skepticalaquarist.com/municipal-water-softening

So I don't think limed water contributes CO2 in an aquarium.

Lime softening removes almost all the CO2.

They add CO2 to such water in fact, this is to prevent such high pH's, partial lime softening can take care of some of this, but the pH comes out at 10.1, if the tap is 8, then they need to mix a lot to stay within the pH optima for distribution and other downstream processing in the water treatment.
This is done using CO2 gas enrichment. It is generally avoided, but there are times when it's needed and the delivered product is mandated to have a specific Calcium /General hardness/Alkalinity range.


It's only going to occur where your tap is normally very hard and they treat at the treatment plant to reduce the Ca/Mg mostly.
 
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After months of comparing frequent water changes (multiple times daily, daily, every other day, bi weekly) and weekly or twice monthly water changes, I see no improvement in growth with more frequent water changes. I notice no "bump" in growth as some have described. In fact, it's the opposite. If I do more water changes, plants seem to grow slower. If I don't do water changes, they appear to grow faster probably because I'm already adding CO2 and WCs reduce the amount. That may have to do with the water from the tap.

San Francisco tap water: out of the tap, pH=8.4. After passive degassing for 24 hours, it drops down to pH=7.4-7.6. Active agitation with an air stone drops it down to pH=7.2-7.4 in less than 10 hours. pH should climb as one would expect if the water were rich in CO2 and degasses, but that's not what occurs; pH drops. kH=2, so according the the pH/kH table, out of the tap, CO2 =0.2ppm. After air stone degassing, CO2 =3-4 ppm. There's more CO2 after degassing than there is out of the tap.