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Discussion Starter · #22 ·
Thanks all, I don't know what to do.....I was just going to have a slow flow through so the loss of co2 is minimal and on the return have an inline co2 diffuser and a one way ball valve to stop flooding in case of power outages. If water movement is the key I dont really know how to best achieve it
 

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Duzzy, water movement is only one of the keys. We got a bit sidetracked from your original concern:

To reduce CO2 loss, you want to reduce surface ripple. Have your spraybar set at an angle that only barely ripples the surface. Don't worry so much about how many times your water volume is turning over. If you see detritus setttling on leaves or other surfaces in your tank, then you should re-evaluate circulation.

-Dave
 

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Growing aquatic plants doesn't require a fixed, immutable set of conditions, or else the plants all die over night. I am a good example of someone who can grow plants under far from ideal conditions. You can grow plants with just fish poop as fertilizer, with no filtration, with low light, with algae all over the place, etc. What we are trying to do is grow them well, healthy and vigorous. That is what requires the good conditions, including good water circulation. As I see it, the real dispute is over what constitutes good water circulation. That issue is still up in the air. But, the trend seems to be towards a lot more circulation than we used to see in planted tanks.

We went through something similar with light intensity. We kept learning that we needed a lot more light than we were used to. So, people kept adding more light. Eventually we reached the point where we were using more light than we needed and causing as many problems as we were preventing. Perhaps water circulation will follow that path too.
Hoppy at this stage of the game for me I could clearly say based on my own personal experience that high flow is not necessary to grow healthy aquatic plants in an algae free environment long term. It really depends on alot of conditions, but the point I'm making is higher flow is not an absolute. I've kept filterless nano tanks long-term with no algae and very healthy plants. So other than stirring in some dry ferts with a spoon and having a shrimp crawl around the plants grow healthy for a year with no algae issues. So I would have to assume they arent' getting much in terms of flow. That's not to say that there could be a case where higher flow might help someone, but it still hard for me to comprehend that you need anything more than alittle movement to move ferts and dissolved co2 around two to four feet of water.
 

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I remember when air stones where all the water movement we had. The tanks where clear and some grew plants, thought not as well as know. I would just like to add that an adequate co2 diffuser will move water as well. And as some one stated water changes with a gravel vac will also stop build up. I have chased the water flow dragon for algae problems, but I never found it to be and answer. though my opinion on this does change often, I think some controlled experiments are in order. Any volunteers?
 

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one thing I think we could possibly agree on is that, first off, aquatic plants are collected for different regions from all over the world each of which has grown and evolved in the conditions available, ie lakes, rivers and bogs. Therefore every plants threshold for not only the flow of water around it but also light intensity, iron levels, ph levels and so on and so on, are geared for the environment. With that being said these things are what is considered when re-creating those bio-topes in our tanks. I don't think it's fair to say that it is simply black or white for the flow. I do like the idea of a controlled experiment though, seems that would be the only way to really find out for sure.
 

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Discussion Starter · #27 ·
Thanks all,

I think I will get a pump suitable for say 6 times the tank volume and see how that goes. I will say that I do not plan on using a spray bar I think they look woeful. I also am unsure if I should split the return in 2 or just keep the 1. Man every answers seems to give me more questions lol thanks all

Regards Darren
 

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Hoppy at this stage of the game for me I could clearly say based on my own personal experience that high flow is not necessary to grow healthy aquatic plants in an algae free environment long term. It really depends on alot of conditions, but the point I'm making is higher flow is not an absolute. I've kept filterless nano tanks long-term with no algae and very healthy plants. So other than stirring in some dry ferts with a spoon and having a shrimp crawl around the plants grow healthy for a year with no algae issues. So I would have to assume they arent' getting much in terms of flow. That's not to say that there could be a case where higher flow might help someone, but it still hard for me to comprehend that you need anything more than alittle movement to move ferts and dissolved co2 around two to four feet of water.
Today I picked up a little more information. I was, along with a couple of other guys, helping Tom Barr move a 120 gallon tank into his house and we were talking about CO2 a little. He knows I have been puzzling over the need for so much water circulation. He mentioned that he had used his expensive CO2 meter to measure the ppm of CO2 in his 180 gallon tank, and asked me to guess what the results were. This tank has very good water circulation compared to anything I have had, with big Aquaclear filters and a big pump driving them, plus dual filter outlets and inlets in the tank. The results he got were: about 120 ppm near the filter outlet where the enriched water enters, about 40 ppm near the middle area of the tank, and 10 - 20 ppm down near the bottom in the middle of a bunch of plants. You have to admit that is astonishing. He has only cardinal tetras and some pencil fish in there - small fish. None were bothered by the CO2. (He is quite sure that larger fish would have been very much bothered by those levels.) And, even with the great circulation he had, the gradient in CO2 concentration was way beyond what he expected. So, he now has a big modified powerhead, with the model boat propeller modification, at one end, adding a whole lot more circulation.

The obvious question is how much did that help. But, the CO2 meter is out on loan to someone now, so he doesn't know yet. I'm still convinced that water circulation is an area where there is a whole lot more to learn. One thing I learned from this is that the CO2 we inject doesn't just come out of solution at the water surface, the plants are consuming large quantities of it. That should be obvious, but I hadn't really thought of it that way.
 

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Well I did say 2 to 4 feet. LOL.

My question is how are the plants doing on the far end of the tank where the co2 ppm was lower? Is there any difference between the ones near the return? I could tell you I have a 4ft tank with an eheim ecco and it effectively turns over the water once per hour. There is a spray on the left piece of glass angled down 45 degrees with a ceramic diffusor right below it. So the co2 goes up, hits the spray bar and is pushed left to right across the tank. There are two main rotala rountifolia groupings. One right near the spray bar and one on the far side side and their is no difference in appearance between the two groups either in fullness, color and pearling activiity. The testing might open a whole bunch of interesting information. I certainly will not doubt any of the readings from the tests taken, but one needs to just look at the plants to see what is necessary. And whether the co2 ppm is 100 near the return and 10 near the opposite side if the plants are growing great it tells me I don't need additional circulation and/or maybe we don't need 30ppm co2 as well. I don't believe any parameter works in a vacuum including circulation.
 

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Well I did say 2 to 4 feet. LOL.

My question is how are the plants doing on the far end of the tank where the co2 ppm was lower? Is there any difference between the ones near the return? I could tell you I have a 4ft tank with an eheim ecco and it effectively turns over the water once per hour. There is a spray on the left piece of glass angled down 45 degrees with a ceramic diffusor right below it. So the co2 goes up, hits the spray bar and is pushed left to right across the tank. There are two main rotala rountifolia groupings. One right near the spray bar and one on the far side side and their is no difference in appearance between the two groups either in fullness, color and pearling activiity. The testing might open a whole bunch of interesting information. I certainly will not doubt any of the readings from the tests taken, but one needs to just look at the plants to see what is necessary. And whether the co2 ppm is 100 near the return and 10 near the opposite side if the plants are growing great it tells me I don't need additional circulation and/or maybe we don't need 30ppm co2 as well. I don't believe any parameter works in a vacuum including circulation.
I agree. As usual, all of his tanks looked very good. He had a several day power outage while away, so he lost some plants and fish from that, and is still cleaning up the tanks, but they looked great to me, all over. Some day it will be possible for someone to say with confidence that we need at least X ppm of CO2 for the plants to do their best, but I don't think we are near that yet.

One thing to consider - if the CO2 is being consumed fast enough by the plants to lessen the concentration that much, the other nutrients must be depleted about as fast. So, circulation also acts to replenish them, too. But, I can't deny that whatever conditions he had, his tanks look great.
 

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One thing to consider - if the CO2 is being consumed fast enough by the plants to lessen the concentration that much, the other nutrients must be depleted about as fast. So, circulation also acts to replenish them, too. But, I can't deny that whatever conditions he had, his tanks look great.

Brings up alot of interesting points. Is circulation more important in a high light/tech tank if things are depleting faster? Do plants react to their environment based on flow and other variables and store things they need to continue to grow. If you consider a filterless nano tank that might get semi-weekly wate changes and the plants grow great. Are the water changes enough to move things around and get the plants what they need until the next water change, etc.
 

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I'll volunteer to do a test, but it won't be as scientific as what might be desired (because I do not do water tests and don't own any test kits). But I could tell you if I notice any differences from what is currently going on in the aquarium.

Right now I've got an emperor400 HOB filter (it's got the bio-wheel on it) on the left-middle of my tank ( 50 gal, 48x12x18 ) . I've got a powerhead on the right/back corner (set on an UnderGravelFilter) set at an angle to assist in circulation to get water from the right-side to the emperor.

I can turn off the HOB and run only the powerhead (which doubles as my DIY CO2 reactor). That would cut off the majority of my water movement since the emperor pumps about 350 gph (is that right? It's rated at 400, but with filter cartridges....) and the powerhead only about 95gph. With the density of plants I have, circulation would be all but stopped on the left half of the tank. I'd essentially go from 9x per hour of turn-over to 2x with heavily reduced circulation.

Would this be worth doing without having the test-kit results to provide hard data?

-Dave

BTW, lighting is 2x65watt PC 6700/10000K; plus 2x15watt "Aquarium Bulbs" (came with original hood) that light the shaded spots in the foreground.
 

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What I was thinking of was 2 tanks with identical setups, the only variable would be water movement. It is nice for your to offer your setup but think this may have other things affecting this as well. You have a biological filter built up in that wheel. Your tank is accustom to having that ammonium uptake with out it you will have excess ammonium, causing an algae bloom. aka green water, I have done this. By the way If you have co2 and a bio wheel the wheel is spitting out the co2 as fast as you are putting it in. My be your could turn off the power head and see what that does.
 

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http://www.barrreport.com/co2-aquat...eal-time-data-localized-co2-ppm-readings.html is Tom's own report on his CO2 measurements, for those interested.

I admit that I have no ideas at all about how to measure the effect of water circulation. It is easy to try increasing the circulation and see what happens, but if the plants grow better, you lose some of that increased circulation, canceling out the effect. You can also reduce water circulation and see what happens, but who wants to risk an algae outbreak? The idea of 2 otherwise identical tanks, one with a powerhead, preferably a Koralia, adding a lot more circulation, seems to be the best experiment that is possible for one of us to do.
 

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Yes, I suppose I'd be pretty miffed at myself if wound up with tons of algae all over the place after shutting down my main fliter just for kicks.
Well, that rules me out of conducting the test. My "Financial Manager" (the Mrs.) would never let me get away with buying another tank (or two)...well, not anytime soon.
 

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Yes, I suppose I'd be pretty miffed at myself if wound up with tons of algae all over the place after shutting down my main fliter just for kicks.
Well, that rules me out of conducting the test. My "Financial Manager" (the Mrs.) would never let me get away with buying another tank (or two)...well, not anytime soon.
Vary nice of you to offer your tank. I am in the same position as you, my "Financial Manager" wouldn't let me do that either. :(
 

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http://www.barrreport.com/co2-aquat...eal-time-data-localized-co2-ppm-readings.html is Tom's own report on his CO2 measurements, for those interested.

I admit that I have no ideas at all about how to measure the effect of water circulation. It is easy to try increasing the circulation and see what happens, but if the plants grow better, you lose some of that increased circulation, canceling out the effect. You can also reduce water circulation and see what happens, but who wants to risk an algae outbreak? The idea of 2 otherwise identical tanks, one with a powerhead, preferably a Koralia, adding a lot more circulation, seems to be the best experiment that is possible for one of us to do.
I continue to find this discussion very interesting. I have been reading Tom Barr's thread as well. It seems hard to imagine with that much flow that he has such a variance in CO2 measurements, but you can't argue with the facts. The next question is why? Can some plants actually take up the CO2 so fast that he'd get such fluctuations? Then I ask, so how do we overcome the fluctuations if at 18X turnover he still has such fluctuations? Do we plumb our tanks so that the CO2 enriched water is released every 25-30 cms around our tanks? It will be interesting to see if there is any resolution.... :cool:
 

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Discussion Starter · #38 ·
Well my financial manager has just said I can get a 4x2x2 what ya reckon should I ask for a second one lol

thanks all for the info there seems to not be a firm answer on this as of yet.

So now the question is. If I have my 4x2x2 with its weir/overflow in the center. And face 1 return to the left and one to the right creating two semi circles of water flow and back to the weiw would that be ok? and on the returns I have something like this
 

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I use a filter return like the one in that photo, and I really like it. It creates good water flow, but doesn't blast the water into the tank so fast it tears up the plants and substrate. Your two outlet plan sounds good, but a lot will depend on how dense the plants get, and how much they block the flow.
 
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