Green water and UV Sterilizer

[reiverix]

Forgive me if I am replicating an already covered topic, but I have been searching through forums all afternoon and need advice specific to my exact setup. I've broken my post up into three sections. If you want to skip some of this ramblings, or just have a life, my questions are posted at the bottom.

______________________MY TANK______________________

55 gal

4x40w fluorescent Lumichrome 1XX 6500K full spectrum 98 CRI with reflective tape on shoplights. sitting 3/4 inch above top lip of tank. On a timer for 10-11 hour photoperiod.

Eheim 2026 with the blue pad, noodles, sintered glass dogfood stuff and fine white filter pad

Hydoor ETH 300w inline heater attached to return line, about 5 inches below the top of the tank and hanging vertically, set to 77 degrees.

3 bags, 45 lbs, 2 inches of flourite substrate.

Spectrapure RO water - reconstituted with 1tsp of Kent R/O Right per 10 gallons (soft water dosage) and 1/2tsp of sodium bicarbonate per 10 gallons.

Wardley's chlorOut at slightly less than recommended dosage, I dose 10 gallons with about 7-8 gallons worth of chlorOut...the activated carbon filter in the RO unit is supposed to filter out chlorine at a rate of 1ppm for 9,000 gallons. I dose just in case there are chloramines in the water.

I run yeast powered CO2 into a homemade in-tank reactor and my levels range from 16-25ppm, depending on lots of things...I've been doing a lot of water changes and so forth lately...you'll find out why.

It should be noted I plan to switch to compressed CO2 and an external reactor as soon as I get rid of my current dillema.

My PH is usually between 6.6-6.9, depending on the above CO2 specs. My alkalinity is around 3.8-3.9. I am not sure what my hardness is, I think my test kit is broken because at my dosages of R/O right, it immediately turns the final color after only one drop, and I am dosing the R/O right at twice the recommended dosage for discuss (I don't have discuss, just using that as a point of comparison) Straight out of the RO unit, the ph is in the mid to high 5's and the alkalinity and hardness are at 0.

Ammonia, Nitrates both at zero. I know the nitrates should be higher, but once again, all these water changes.

The tank, once grown out, will be moderately planted. Glossostigma, and other plants that were part of a low-light setup.

14 Rummynose tetra, 10-11 Otocinclus, and a recent swarm of about 55-58 Amano shrimp.

I feed New Life Spectrum Small Fish Formula twice daily. I feed all that the school of tetra can eat in a 10 second period. There is never any uneaten food. I occasionally drop in a few New Life Spectrum H2O Stable Wafers if I'm feeling anxious about how well the algae eaters are eating. I've only had these shrimp for about 4 days so I'm not sure how my algae is supporting them. It's hard to see. You'll understand why in a few seconds.

I was doing 10-15 gallon water changes weekly, but for the last 2 weeks have probably been doing close to 45-50% water changes weekly. I sometimes siphon, sometimes dip water out.

I was doing Kent MicroNutrients only, at a rate of a little less than 50% the recommended dosage. I know...I was still doing research on fertilizing and figured it was better to do nothing than to ignorantly do everything in execess.

The plants look great, especially considering I took them all out and bleached them. All the leaves died, but the regrowth is much nicer than the original growth. That was all due to a problem with my tapwater than the RO unit and Amanos have eliminated.

_______________________MY PROBLEM______________________

I have green water. It looks like a tank full of thick poisonous gas. It starts to get better and then gets worse. I was doing 10 gallon changes a day and it started to clear, but would never get completely clear. If I relaxed thinking it was over, bam the green was back.

Here's how it all began. I had hair algae, super duper bad. I also had a lot of green algae on my back glass. Here's where I messed up...all with the period of a couple days I:

1. Scraped all the algae off into the water
2. Started doing water changes to slowly introduce the RO water
3. Bleached my plants

Dumb..I know...now.

Immediately I got green water and haven't been able to get rid of it for the last 2-3 weeks.

____________________MY QUESTIONS_______________________

I want a UV sterilizer. I will be placing an order for PMDD and hopefully getting them in sometime next week.

Consensus seems to be that the Turbo-Twist won't be a dissappointment. Based on what I have provided, I need answers to these questions:

1. Should I run the UV inline from my Eheim 2026 or should I run it inside the tank with a dedicated powerhead? I would prefer to run it 24/7 IF it will perform well with my Eheim's flow.

2. Depending on your answer to the above question, which TT model do I need, the 9w or the 18w?

I realize I have a greater responsibility than to simply zap the evidence of my problem, but I know I need to do this if I ever want to have a chance of getting my aquarium back into a natural balance. I can't very well do much observing of my fertilizer dosages if my water is already puke green before I even start.

Any help would be greatly appreciated.

 

[travis]

Re: Green water and UV Sterilizer

The wattage of your UV sterlizer should be chosen based on the gph rating of your pump. I would recommend placing it inline with your canister although it may also work in-tank. The sterilizer should include information relating to how many gph it is rated at for full sterilization as well as for simple clarification (clarification requires less dwell time for the water under the UV light). I run a 25w Aqua UV sterilizer on a Rena Filstar XP3 canister filter (in-line) rated at 350 gph and it works wonders in my 125G. I have never experienced any issues with green water or had a single sick/infected fish since I started using it almost a year ago. Hope this helps

 

[reiverix]

Re: Green water and UV Sterilizer

The wattage of your UV sterlizer should be chosen based on the gph rating of your pump. ... The sterilizer should include information relating to how many gph it is rated at for full sterilization as well as for simple clarification (clarification requires less dwell time for the water under the UV light). I run a 25w Aqua UV sterilizer on a Rena Filstar XP3 canister filter (in-line) rated at 350 gph and it works wonders in my 125G. Hope this helps

I read something that stated elbows decrease flow by about 5% and joints decrease flow by about 2%. Interesting.

There is a chart in a Foster&Smith catalog that provides a GENERAL idea of UV/flow relationships. I believe this chart applies to the general straight-through UV design, assuming swirls, twirls and twists in the UV unit has any actual measurable impact on the performance versus wattage.

wattage---------max flow for bacteria/algae--------max flow for parasites

--8w--------------------120gph----------------------------n/a
--15w-------------------230gph---------------------------75gph
--18w-------------------300gph---------------------------100gph
--25w-------------------475gph---------------------------150gph

...and so on

If this general chart is to be believed, then your current setup, running at 50% of the ideal manufacturer's rating, puts you at 175gph, 25gph over the parasite spec. But I'm glad to hear it works just fine for you. Of course, the real world flow rates and the general chart rates are both estimations, so there's give and take on both ends. I've read that the Aqua UVs are more efficient than many other brands, so you may be getting more killing for the same amount of wattage. I dunno.

If I take your successful gph/wattage ratio, scale it down to apply to my situation and give myself a 25gpd buffer zone, then that puts me at 125gph, which is 25gph over the parasite spec for a 18w UV sterilizer.

Sounds like 18w should be the smallest unit I consider and the most appropriate. The Turbo Twist comes in 9w and 18w (and other much larger units), so if I go with the 18w it has a manufacturer's rating of 200-300gph, which my Eheim manufacturer's rating of 250gph falls right in the middle of. I think I'll give it a try.

Thanks for your response, it game me something "real" to work from.

 

[reiverix]

Re: Green water and UV Sterilizer

There's something else I'd like to get some thoughts on as well.

How are the UV sterilizer ratings assigned? Are the manufacturer's and general ratings based on the killing power of a single pass of water. What I mean is, are they rating their units on a theoretical situation where contaminated water is pumped from a source, through the UV sterilizer, and out to a drain, with only one exposure to UV light, or are they rating their units on a closed, recirculating system, such as our aquariums, where water is exposed and then refiltered and re-exposed?

How does re-exposure effect UV sterilization? Could you use a UV unit rated at half of the recommended wattage and still get 100% destruction only taking a little more time to accomplish as it would need maybe 3 passes?

If you expose contaminants to UV light too weak to destroy them in one pass, do the continuous passes "add up" or do the contaminants simply endure the weak exposure over and over and over again, never being completely eliminated?

 

[travis]

Re: Green water and UV Sterilizer

My guess is that the ratings are based on a single pass kill. I say this because flow rates are almost always used rather than any references to tank size, but I could be wrong. I also doubt whether my XP3 pumps at the rated 350 gph. I suspect this value was derived from testing it without any media in the baskets

 

[reiverix]

Re: Green water and UV Sterilizer

That makes sense. So now the question is can algae or parasites completely recover from individual bursts of less than fatal exposure and if so, can they perform a 100% recovery BEFORE being re-exposed under normal circulation conditions? If they cannot perform a complete recovery in time, which would need to be roughly 10-20 minutes based on normal filter circulations of 3-5x water volume / hour, then people running UVs 24/7 inline should be able to get the same preventative results from much much less than recommended wattages or with much higher flow rates for any given wattage.

Are we spending way too much $$ on UVs?

 

[travis]

Re: Green water and UV Sterilizer

Only one sure way to find out, but it might be sort of painful to be the guinea pig in this case

 

[Greg Watson]

Re: Green water and UV Sterilizer

Are we spending way too much $$ on UVs?

This deserves a thread all of its own, simply replacing "UV" with "Product X" ...

If Product X makes maintaining your aquarium 2% easier or makes your aquarium look 2% better in your own judgement ... then the question becomes one of individual judgement ...

For a lot of people $100 for gadget X is a lot of money, and for them to justify that much money requires a lot more than say a 2% improvement ..

But for the next person, $100 may not mean very much compared to getting rid of a small little 2% annoyance ...

So there really is no single correct answer to this type of a question ...

I think a UV "masks" a lot of little problems so that you never see them ... in other words, I think a UV will kill a lot of little algae symptoms of a lot of other little problems ... without addressing the cause ...

That said, I'm very comfortable spending the money on a UV and I'm very comfortable with the "cost" of running it 24 hours a day which also means replacing the UV bulb once a year ...

Greg

 

[aquabillpers]

Re: Green water and UV Sterilizer

According to Kent, R/O Right does not supply enough calcium or magnesium to support aquatic plant growth. I believe it was designed for salt water use.

That might be contributing to your problems. You'll have to either add the missing minerals or reconstitute your RO water with Seachem Equilibrium, which supposedly provides all of the required minerals in the right proportions. It might need to be augmented with something to increase the KH.

Bill

 

[reiverix]

Re: Green water and UV Sterilizer

That said, I'm very comfortable spending the money on a UV and I'm very comfortable with the "cost" of running it 24 hours a day which also means replacing the UV bulb once a year ...
Greg

I think I'm pretty comfortable with the idea too

I'm in the unfortunate position of needing both a UV and pressurized CO2 system at the same time. Compound this with my curiosity of multiple passes at low wattage and I think I've decided to grab a 8-9w unit and let you know what happens. Jumping to 18 watts is an increase of about $50..that's a 5lb aluminum CO2 cylinder.

One thing is for sure, if the UV gets rid of my green water then it will be a 200% improvement!!

I don't know anyone personally that understands my appreciation for naturally aquascaped aquariums and therefore my willingness to spend money on it.

As far as my questioning if we are spending too much money on UVs, I'm wondering if say 8w systems would be enough on even large tanks with good filter turnover as long as they are being used as prevention and not, as in my case, to irradiate a large amount of undesirable material in a short period of time.

It would be interesting to take a healthy 150 gal tank or larger with 3-5x turnover and an inline 8w UV and systematically introduce small amounts of algae or parasites to simulate an early breakout in a healthy tank and then see if the smaller UV can keep things in check with it's multiple passes of low UV.

If someone would donate a 150+ gal tank and an 8w UV I would be glad...

According to Kent, R/O Right does not supply enough calcium or magnesium to support aquatic plant growth...You'll have to either add the missing minerals or reconstitute your RO water with Seachem Equilibrium...

May explain why my GH readings are nill even after dosing the recommended amounts. Although, I am not seeing any symptoms of deficiencies yet and it has been weeks.

Thanks. I will add Calcium and Magnesium to my list of ingredients and check for them. I would actually prefer to have independent control of them anyway. I haven't begun the dosing thing yet because I'm still working on getting a reliable CO2 setup. I think my mom has some supplement tablets in the kitchen....hmm...

 

[Greg Watson]

Re: Green water and UV Sterilizer

I think I'm pretty comfortable with the idea too

As far as my questioning if we are spending too much money on UVs, I'm wondering if say 8w systems would be enough on even large tanks with good filter turnover as long as they are being used as prevention and not, as in my case, to irradiate a large amount of undesirable material in a short period of time.

Ok, this is pure speculation, but somewhere deep in the unused parts of my mind, I think I remember something about the wattage being more linked to the flow rate than tank size ...

There are a lot of low wattage pond UV sterilizers being used on very large ponds ... so I suspect that in the typical range of aquarium sizes, that the rated flow rate for the UV sterilizer is more important ...

Greg

 

[reiverix]

Re: Green water and UV Sterilizer

Right, I agree. My understanding is that UV ratings are basically "time" ratings, as related to exposure, rather than volume ratings. The size of the job doesn't matter (realistically of course) as long as the UV gets enough time with every unit of water that goes through it. For example...a 9w UV sterilizer could sterilize the ocean, given enough time and assuming that the biological contaminants weren't capable of reproducing themselves back into the clean water...which is what concerns me about the UV ratings and how they reflect the performance of UV sterilizers in closed circulating systems. If they are rated based on their ability to kill biological contaminants in one pass, then they are rating these devices to be used like RO units, where bad water enters from body A and good water exits into body B. This is not how the units function in actual use, as our systems are circulating, intermixing, and then being re-exposed.

If UV ratings are based on one-pass kills, then:

A fictional example of an 18w UV unit that has a maximum rating of no more than 100gph to neutralize parasites really means the unit needs at least .6 seconds of exposure time to give the parasites enough UV at an output of 18w to kill them completely, or at least to damage them enough that they soon die, without the need for re-exposure.

It takes x number of seconds to kill biological contaminant z, assuming the UV can penetrate the depth of water it's confronted with in the tube. For example, a 100w unit that was 20 feet in diameter couldn't sterilize water even if it was running at 1gph because it probably wouln't penetrate to the center of the water column.

What I'm wondering is if there is any data on repeat exposure and it's effects. It's a totally theoretical question. It doesn't have a huge impact on our decisions on what size UV unit to buy or what flow rate to run through it. I'm just wondering if we could realistically divide the recommendations in 1/2 or maybe even 1/3 and still get the same results, over a longer period of time, and save ourselves money by not buying larger units, or even properly rated units, that may be overkill (pun intended).

It all boils down to this:

Random example...if an 18w unit is rated at 100gph, then it needs .6 seconds of CONSTANT exposure to destroy a certain material. What if you exposed that same material for that same amount of time, but this time you were exposing it to a 9w unit. Obviously, the 9w unit wouldn't be able to destroy it in one pass but could it destroy it in 2 passes, say 15 minutes apart, or maybe 3 passes at 15 minute intervals? If so, then UV units are rated waay too conservatively for most aquarium use because each parasite it being exposed multiple times per hour under normal circulation conditions. Even if it takes more than one pass to kill a parasite with a unit running at a higher gph than it is rated for, it could still purify your aquarium as long as it wasn't soo big that the parasites had time to adequately reproduce once or twice before they got sucked back into the UV for their second exposure. Unless you are filtering Shamoo's aquarium with an Eheim 2026, your parasites are going to get multiple exposures through circulation before they can reproduce 1 or 2 generations.

Maybe I'm not being clear on what I'm getting at, or maybe you're just trying to tell that it isn't worth pondering because we're only talking 50 bucks Still, it would be interesting to know.

 

[Vladimir Zhurov]

Re: Green water and UV Sterilizer

When dealing with UV light sterilization you have to keep in mind that while it is true that repeated low intensity exposures may be as effective as a single-pass high intensity one there are two factors to consider. They are intensity of UV radiation and duration of single exposure. With the latter being inversely proportional to flow rate. From here you can estimate UV dose of single exposure.
I would suspect that if you will decrease it too much through using low wattage UV unit with high flow you will not harm microbes at all. Likewise you can quickly move your hand through a candle flame repeatedly without any damage given some time to cool down between moves.

Regards.

Vladimir.

 

[reiverix]

Re: Green water and UV Sterilizer

I really DID order a UV sterilizer after the above discussions, it just took it this long to get to me. Everyone was on a 1 month backorder. Well, I've had it for about 2 days and here is what I can DEFINITELY say about them...

55 gallon FW tank with thick green water for a good 1.5-2 months. I could see about 1.5 inches into the tank from the front, that was it. I ordered a 9 watt Turbo Twist. I used 1/2 hose to connect it to a Maxi-Jet 900.

So, we have super bad green water, a 9 watt UV sterilizer, and a pump pumping 230 gph through it.

I did not do a water change before running the UV. I have not done a water change during the UV treatment. My water is already the clearest I can ever remember it being, and it's getting clearer exponentially. Remember, this is only a 9 watt UV and I'm running a whopping 230 gph through it. I would say based on this that you don't need high wattage and you don't need low flow, at least not for green water, and I believe it should also be effective against parasites since this proves multiple low passes DO add up. I think we need to remember that it looks like the wattage:flow ratings seem to be based one single pass kills, which is needed if you are, say, sterilizing water on it's way through a utility pipe to someone's faucet, but not needed in a closed recirculating system like an aquarium, where the microbes are being exposed and re-exposed several times an hour. You simply don't need that kind of killing power because you are getting multiple exposures.

I am extremely impressed. Honestly, they don't charge enough $ for these things. It's the closest thing to magic I've ever seen.

One big flaw here is that I didn't take a BEFORE picture, just please trust me that this water was BRIGHT green and super thick. After one day with the UV, I saw plants that I didn't even know I had had grown in.

Truly awesome. I'm totally re-energized for this hobby.

 

[gpontis]

Re: Green water and UV Sterilizer

Glad to hear that this worked for you. When it comes to mulitple passes working, I am not sure you can conclude that. Different organisms can withstand different amount of UV exposure. My understanding is that algae is pretty easy to damage, so you are getting good results with a single pass and high flow rate. Maybe better than at recommended flow rates due to the faster turnover. If you were depending on the same UV unit to kill a protozoan, it might not deliver enough of a dose to do the job.

I have a couple of UV sterilizers and some experience to share. My first lesson was that I was not able to maintain a reasonable level of iron in one tank when I turned on the UV. This was a 37G tank with Eheim 2224, I think pumping about 140GPH through a Jebo 9W UV. I am sure that I could have maintained a usable iron level if I dosed every day, but without the UV I would not have to dose for 5-7 days. I have been using chelated iron, purchased from Greg Watson's convenient site. I suspected that the same thing (oxidation) would cause a depletion of other trace elements but I don't have a test kit for any except iron.

Now that aquarium is history and I have a 125G tank with a Fluval 404 (340GPH) and a 25W UV sterilizer. I turn on the UV before doing a water change and gravel vac, so the UV can do its thing on anything that is stirred up into the water. I leave it on for an hour or maybe a little less. About when I have the tank refilled I pull the plug.

BTW, the Fluval 404 was new as well as the tank and I loaded in the activated charcoal with the notion that it would take out some kinds of bad compounds that might possibly leach out of the non-aquarium pebbles. It turned out that I could not maintain iron levels with the charcoal in there either! Once I removed the charcoal that problem went away. Interestingly, it seemed perfectly able to pull iron out even after being in use for about 3 weeks.

 

[Tom Barr]

Re: Green water and UV Sterilizer

From the APD, and yep, this is word wrappped :gw



"Okay, one thing no one seems to realize and discuss is that the intensity of the sun's UV's are very high. It is also "always on" during a large portion of the day hitting most of the water.



Compare this amount of UV energy to a UV sterilizer that has water pass through it for 1-2 seconds perhaps 2-10x per hour.



The other issue that the UV's wavelength is different than the Sun's and generally more narrow. Many chemical bonds and complexs are specific to a particular wavelength for degradation.

Given that people have only actually used field data from natural systems to justify the UV sterilizer claims that it breaks down iron complexes, RATHER than any real data from an aquarium, this seems speculative at best and at worst simply wrong/insignificant.



I think the burden should be on those wanting to make this claim to show that it is or is not significant.



The observations with using UV's and dosing traces sure don't seem to support their contention.



I've given several good reasons why.


>The method by which plants
>extract iron from EDTA is when the EDTA-iron is pulled down into the
>root zone where the pH is much lower and thus conditions are
>conducive to extraction of iron by the plants directly as it is
>released from the chelate under the acid conditions or the plants can
>also utilize phytosiderophores to extract the iron directly. However,
>in the water column there is no release of iron (-> insert shameless
>pitch here - use Flourish Iron to target leaves, stems as well as
>root zone - it is non-EDTA based).

*Some plants*, only grasses, (unless you have research suggesting otherwise), utilize phytosiderophores to extract the iron.. People hear phytosiderophores and automatically assume __all__ plants do this. That is not true.



www.rosier-be.com/media/Rosafit en.pdf

http://www.nap-chem.com/Product_Pages/iron_products.htm

http://lee.ifas.ufl.edu/horticulturearchive/foliarfeeding.htm
cecommerce.uwex.edu/pdfs/A3554.PDF

http://www.forestry.auburn.edu/sfnmc/class/fy614/iron.html



EDTA ___is applied as a foliar__(thus leaf uptake does occur in a wide variety of plants) micro nutrient.



DPTH is a better chelator as opposed to EDTA since the pH is more useful for our application.......EDTA is useful up to about a pH of 6.3 whereas DPTH is good for up to a pH of 7.5.



So plants most certainly can and do take in Fe EDTA via their leaves in many agriculatural crops, it is very unlikely that aquatic plants would be any different.



Further:

How do algae obtain Fe? They have no roots and their descendants are root bearing plants, why would they lose the foliar uptake ability? What about Riccia? Moss? Java fern and other plants without sediment bearing roots?



This not does fit well with aquatic plant observations nor with research on foliar applications.

Gentner 1976: Uptake and transport of iron and phosphate by Vallisneria spiralis L.

It appears that aquatic plants do take in Fe from the leaves in the form of EDTA.

Further:

Haller et al 1976 also used Fe EDTA with Hydrilla and found growth rates increase when they had relatively high(very high considering PMDD's standards of a wimpy 0.1ppm range) of 6.0 to 8.0ppm Fe. This was primarily from foliar uptake.

> U.V. light would break down the compound (& chelated nutrients)
>>rapidly and thus exhaust it quickly.

>This would make sense, the chelate would rapidly release the iron which would then rapidly >fall out as iron oxide, thus rapidly removing all of it from the water column so it could no >longer resupply the root zone with this iron source. Eventually the precipitate would work into >the root zone but it would take awhile.
>Greg Morin



That assumes plants can only use Fe in the roots from EDTA and other forms of Fe, but this is not true, see above. Observational experience is counter to this and plants will use some of the Fe prior to it being oxidized.

But the other argument is that the iron would be available for a longer time frame than say a less strongly bound chelator complex. So over time, the iron would be available longer to the plants even if the energy required was a little more to remove the iron from the complex.



This presents a good arguement also.



That's fine if you dose frequently or have low iron demand, but here's an idea for you :

Use both the gluconate form and the DTPH form.

Then you get the benefits of both.



But is the amount energy significant in the various Fe chelator/complex forms to the overall status of the plant of one versus another form? Fe is a trace after all, not much is needed. So is the form of Fe really going to make a difference?



I think having some available whether dosed through DPTH or more frequently from weaker complexs works fine. You can dose pulses also and still maintain non deficent Iron levels as well as using low light tanks to and rely on the sediment almost exclusively.



Regards,

Tom Barr "

So there.

 

[reiverix]

Re: Green water and UV Sterilizer

Is there any way to get hold of parasites to do a controlled test? I would assume most would need a host during the course of the testing, otherwise their deaths could be credited to a lack of hosts. I'm of course not willing to subject a fish to this.

Does anyone have any experience with low wattage or high flow rates or both being used to effectively kill or control a parasite situation? I'm always wary to trust claims made by those that profit from the sale of items. Surely someone somewhere has performed tests and reported their results.

Just how resistant are parasites to multiple low-exposure passes? How does their resistance directly compare to algae? Anyone have ideas for a testing method that is reasonable to carry out?

 

[reiverix]

Re: Green water and UV Sterilizer

2 equal setups: 10 gallons, same water source, same water temp, no plants. Each containing 1 fish of the same species and size and relative levels of ich infestation. One will be the control and the other will be exposed to UV treatment. Observe the fish and record the differences, if any.

I don't know much about parasites but would this work knowing the nature of ich and it's lifecycle?

Also, couldn't I use these tanks to test the effects of UV on iron levels? Dose each plant-free tank with equal amounts and record the iron levels over a period of time? How long does iron last in solution under untreated conditions? At what point should it break down in the control?

I'd like to get to the bottom of this. Dose, expose one and not the other, test at intervals and record the results. BAM! Case closed. Could it really be that easy?

 

[gpontis]

Re: Green water and UV Sterilizer

Wow! I actually had something to say that awoke a sleeping Barr

I must address a few points in defense of my logic and statements and provide some explanation lest I have missed some concepts.

"Okay, one thing no one seems to realize and discuss is that the intensity of the sun's UV's are very high. It is also "always on" during a large portion of the day hitting most of the water.

Compare this amount of UV energy to a UV sterilizer that has water pass through it for 1-2 seconds perhaps 2-10x per hour.

I wouldn't want to trivialize the power spectrum of the sun, but thankfully we have an ozone layer and atmosphere that protects us from the harshness of the solar radiation in space where the UV is very strong. I searched the web for a while to try to find some useful numbers and was only partially successful. Most references just say that no UV-C reaches the earth. In some data taken at the Mauna Loa observatory (elevation 3.4km) on a clear day, there was a plot of irradiance -vs- wavelength that went down to 290nm:

http://www.cmdl.noaa.gov/star/uv.html

The irradiance is falling off exponentially below 310nm. At 290nm it is approaching 5 orders of magnitude below the irradiance at visible wavelengths. The low-pressure mercury "germicidal" lamps that UV sterilizers employ put out most of their energy at 253.7nm which is way attenuated even compared to the bottom of the chart. So I would say that the radiation our aquarium sterilizers produce is not at all natural.

This is borne out all too well by the failures that the early units suffered due to exposure of the internal components to UV-C. Even a piece of window glass will solarize with exposure to one of these bulbs. We never see that happen when natural sunlight strikes the window of a greenhouse, for example.

The other issue that the UV's wavelength is different than the Sun's and generally more narrow. Many chemical bonds and complexs are specific to a particular wavelength for degradation.

Yes, most all the energy is at 253.7 where sunlight is broad spectrum. Also I do agree that there is much in the structure of molecules that is wavelength-specific. One of the reasons that the UV lamps can sterilize is that thymine molecules in DNA can be altered very effectively at 265nm, and the 253.7nm energy is close enough to do the same thing. But there is also the concept of activation energy, which in many systems represents a level of energy below which little happens and above which a reaction is likely to take place. Photons at this short 253.7nm wavelength have high energy and are very effective at providing enough oomph to power processes and promote chemical reactions. For example if you take a mineral that will fluoresce, you can make it fluoresce with any wavelength that is short enough. You don't have to hit it with one specific wavelength. If you let a toaster heat up some bread a too much, it turns black and there's no going back because a chemical reaction has taken place. That same reaction can't be duplicated in a finite time if the temperature is too low. There is a wide range of temperatures over which that will happen. I would say that the high temperature (average kinetic energy of molecules) is putting energy into the system to drive a reaction in the same way that the photon of UV-C light does when it hits a molecule.

Given that people have only actually used field data from natural systems to justify the UV sterilizer claims that it breaks down iron complexes, RATHER than any real data from an aquarium, this seems speculative at best and at worst simply wrong/insignificant.

I think the burden should be on those wanting to make this claim to show that it is or is not significant.

The observations with using UV's and dosing traces sure don't seem to support their contention.

It sounds like you and others have plenty of experience to show that a UV sterilizer is not incompatible with a successful planted aquarium. I am glad to hear that because the UV units have a useful function.

Next time this subject comes up I will direct them to this site for some authoritative information. Or at least limit my comment to say that I noticed that whatever my iron test kit reads, it goes down faster if I turn on the UV unit. I am sure that I could repeat that experiment to everyone's satisfaction. If it becomes interesting with regard to planted aquaria I would be happy to set something up.

George

 

[Cornhusker]

Re: Green water and UV Sterilizer

random alias, i'm just curious as to where you get a good price on those many amano shrimp you have. that many could be a $ disaster in my household. regards,cornhusker