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Equal co2 distribution

Now I remember why I stopped posting here...

Think you are perhaps taking something personal that isn’t personal. I haven’t said anything about your tanks... I’ve never seen them for a start 😂.

I just think that that what you are suggesting in terms of reducing flow as much as possible being a good move, is contrary to what my experience tells me is a good move. Each to their own, and absolutely no reason to get upset about it.
 
If the post had said "I don't think turning off flow would help because too much co2 would accumulate" then I would have gladly clarified that we're discussing how to calibrate flow so my proposal was to turn it off for a FEW hours to understand the co2 dispersion pattern within the tank before calibration. I would also have said that under those circumstances co2 accumulation depends on the rate it is being injected and depends on the geometry and topology of the tank, and if all drop checkers placed within a tank goes yellow within a few hours under no flow (which, by the way, I have never seen in a planted tank) then it means there is no issue with co2 dispersion and when you switch on the pumps a re-testand co2 dispersion decreases then you know that turbulence and degassing (due to increased surface agitation if your are using canisters) are the most likely causes for co2 loss - inside that particular tank and then you can calibrate your flow accordingly.

But he ended by saying this proposal was irrelevant and my tanks will not succeed that way etc. which is just a judgement and disincentives people like me from having any meaningful discussion.

And on top of now I have to deal with being told that I am not tolerating opinion and am somehow attacking UKAPS, which just tells me that maybe I should be spending my time elsewhere.

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Easternlethal, I really don't think your ire is warranted here. Your post was possibly misunderstood, perhaps, as you say, there was confusion regarding turning pumps off permanently vs temporarily.

I for one, agree wholeheartedly with these sentences in your post:
The results might surprise you - because bad flow i.e turbulence excessive / surface agitation can actually decrease co2 in the water.

Having an understanding of co2 distribution in a tank before without flow makes it easier to calibrate it. Sometimes, a well placed powerhead is more effective than upping turnover - as far as co2 is concerned.
I cannot speak for aquascape1987 but I suspect he would agree also that of course, excessive turbulence and agitation off-gases the CO2. And yes powerhead=flow, so there is no debate there, however, the choice is as much for aesthetics as it is for effectiveness.

Now, I'll point out that you yourself opened your post with:
I'm going to suggest something highly controversial.
So here we are with controversy. Why bash the forum with statements regarding posting here due to controversy?
You are free to post here, or wherever you choose to, and while we wouldn't wish you to stop posting here, neither are we to be held hostage to someone's oversensitivity. Where is it written that meaningful discussion must be devoid of controversy?

I've not tried your test method with pumps switched off and multiple DCs mounted in various locations within the tank but it sounds fascinating. Can you elaborate further? Can you share any sketches or photos/videos? This might help others.

Cheers,
 
@Easternlethal - Polite gloves off now, because I’m not going round in circles with you, so this is my last reply to your ridiculous outburst here.

I’m on here to learn and talk about aquariums, not argue with people who get upset and offended as easily and unreasonably as a 5 year old school girl.

For the record:

I didn’t say WAS irrelevant, I actually said NOT SURE HOW relevant....

In a normal mature discussion, that would simply be your cue to chime in and explain to me the relevance and perhaps correct me if I had misinterpreted what you were suggesting...... Look at the quote below- End of conversation on that one.

I’m not sure how


On this aspect:
I cannot speak for aquascape1987 but I suspect he would agree also that of course, excessive turbulence and agitation off-gases the CO2
Yea, I’ve already said that:

I think it’s a given that surface agitation causes CO2 to off-gas and leave the water
But I’m still unconvinced that turning the pumps off and mapping the RANDOM process of the molecular diffusion of CO2, will have any influence on practical application in my tank. E.g such as how high I turn up the flow valve on my filter, or if I change the position or direction of my spraybar. After this experiment, I personally, would still be looking for as much evenly distributed flow around the tank as possible. I’ll just crank my bubble rate up to compensate for the CO2 losses through surface agitation, and my plants and fish will still be healthy.....

Perhaps though, in the spirit of healthy debate, if @Easternlethal had just put his argument across, as you do in an adult debate, and instead of being a little (a lot) over sensitive,there’s always a chance he might have convinced me otherwise. Like I said, I’m here to learn.


which just tells me that maybe I should be spending my time elsewhere

Im going to say something controversial here as well... I agree with you.
 
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Back to my original post ref distribution of co2, I wonder what people's thoughts are on the velocity of water coming out of my spray bars. Flow seems to hit water surface halfway across the tank but I can see movement at front glass. Would this be sufficient or am I better off reducing length of spray bar thus increasing output. Bit of a conundrum for me 🤔
Also, sorry to open up a hornets nest with original post.
As always, thanks for your help.
Nigel
 

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Ok, so for me it’s hard to tell looking at the velocity of the water spraying out. I can only tell what’s right/wrong or too much/too little on my tanks by filling up the tank as normal and watching things get pushed around the tank by the flow. Such as co2/o2 bubbles, fish food etc.
 
I have also messed around with the size of the holes in the spray bar as well to get the flow just right for me, without reducing the turnover of the filter. If you are going to do this though, you are better making some experimental spray bars using cheap tubing rather than your actual spray bars as you sometimes have to go too far with increasing the hole size before you find your ideal, and obviously the pipe is no good after that.
Then once I have decided on the size, apply to the actual spraybar. 😀
 
Thinking the same, very difficult to establish from photo. Good tip reference observing food movement,thanks. Think I will keep spray bar as it is for now. I'm fortunate that the spray bars have joins so I can experiment in the future. Key for me is plants are growing quite well. It was just annoying me I had that blind spot. I guess I could also put plants in that position that tolerate a little less co2. Maybe some tall Crypts.
Thanks again, it's always good to get another person's thoughts 🙏
 
I was putting my argument across - maybe a bit too abruptly and directly, but they were factual observations - including about my own perceptions and I do not think I was making any personal attacks.

@aquascape1987 @EA James - I do not think you understood my posts at all but sorry for overreacting. I was too blunt.

@nigel bentley - You have identified a deficient spot in your tank and trying to figure out how to calibrate it.

My point is that in order to know how much to calibrate your flow you need to get an accurate understanding of how it is affecting that spot, so you need another point of reference otherwise you would just be guessing how much to adjust.

And the surest way is to turn off the flow and measure several points in your tank again (see diagram) because a) if one drop checker is yellow then you'll know your configuration is actually hurting that. If b) it stays the same colour then you'll know that your flow is not doing anything. If it goes blue then you'll know your flow has a slight effect over there. This baseline narrows down the possible culprits. Then, to narrow it down even more you look at all the drop checkers again and see how they ALL compare relative to when flow is on. If a) they are all a shade yellower then it's probably something which is affecting your tank generally (like surface agitation). If b) they are inconsistent (e.g they are yellow near the co2 diffuser but blue everywhere else) then you can rule out surface agitation and concentrate just on flow.

Depending on whether you want to address surface agitation or flow you will either adjust the velocity of the output spray bar (hole sizes) or the height (how near the water line and angle). If everything is equal and its just that one spot then maybe consider just adding a powerhead or drilling a hole in the spraybar to spray down to that spot and not change the rest because it's already working well and having 'conflicting' flow would not pose as much of a problem at this stage.

Of course you could just go with brute force and up co2, but that's not always a good approach especially if you later want to migrate towards a larger tank or a wet dry sump. I know that co2 is cheap but it's not fun having to replenish co2 canisters all the time.

Also you do not need to use having no flow as a point of reference. You can still compare two different flow configurations and develop a fairly robust hypothesis.

@ceg4048 here's your diagram. There's a lot to unpack and unfortunately I don't have a more elegant way to explain it and there's probably better ways.

As background I have always used multiple drop checkers but I just refined it a little more after speaking to ADA design because when they developed their lily pipe some of us were a bit confused over how poorly it contributed to good flow (with most of the energy dispersed as soon as the water leaves the output). And I know that ADA designs entire systems so even though it's largely aesthetic, they would still have to be confident that their output stage could distribute sufficient co2 through their heavily planted Nature systems. The answer I got was that flow and diffusion worked together but can disrupt each other and they wanted to find that balance. In my LFS (most of them) I still find mostly heavily planted tanks maintained with less flow - sometimes just a tiny HOB and diffuser. So this method is my way to measure it as best I can using home equipment.
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Ok so now we are getting somewhere to discuss it. It is an interesting concept, but what I do not understand about the method is:

If you switch off all flow whether it be power heads or filters, and eventually the water becomes perfectly still, and you then diffuse CO2 into the water, why would any particular spot not eventually become saturated with CO2 through the process of diffusion, given enough time and enough CO2?

My understanding of the physics of diffusion is that all areas WOULD become diffused with CO2 evenly under these conditions, eventually. My logic is that the CO2 molecules would enter the water, and randomly collide with, and be randomly collided with by the water molecules, and disperse in a random fashion in this way until they were eventually evenly distributed. So the question is, what would prevent a particular area of that body of water, from allowing CO2 to enter it in a perfectly still aquarium... And if the answer is that there is nothing that could prevent CO2 diffusing into a particular area of a perfectly still body of water, then what information does the experiment in fact show you?

I can perhaps understand this experiment if carried out by reducing flow/ surface agitation, but I’m not sure about stopping it altogether because of the logic above.

But again, I’m here to learn, and am open to learn as my logic on the physics is from high school level physics only. Perhaps there is something I am missing about how I understand diffusion?
 
That depends on how high is the rate of co2 you're pushing into the tank. At a certain rate it would rather escape into the air than diffuse through the water column. It's only above that rate when it will start to accumulate.

But the more co2 there is in the water the more eager it will be to escape so the rate at which you have to keep pushing co2 through is exponential and you will actually need a huge amount and a ridiculously large diffuser (relative to the tank size) to really get a still tank completely yellow. If you have a glass vase or nano tank, try it. It's not that easy. In any case wouldn't you still find it useful to know exactly how much co2 you need to push into your tank to make everything yellow?

Of course if you already know then you already have a reference point and don't need to do the experiment.

Also we're not talking about running the experiment the whole day. Just a few hours (just to see how quickly it gets there).

But that's actually another experiment for another time and for this experiment it actually doesn't matter. Because what you're doing is comparing it against WHEN you have flow and it's those DIFFERENCES in colour that you're interested in.


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Here is a 126 gallon extremely low flow low maintenance no fert high light co2 injected tank with 8 drop checkers. You can see from the picture that the surface is absolutely still but plants are pearling and growing well. On the top right you can see the front drop checker greener than the one behind which is rock solid blue - even though it is in the direct path of the inlet which sprays from left to right along the back.

The outlet is near the inlet at the top back left hand corner of the tank.

The area with least flow is bottom front left hand side but drop checker there is also greener than the drop checker in the path of the inlet at the top, and has the heaviest amount of growth. There, I believe that Co2 is delivered through diffusion rather than flow.
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DC barely visible but same colour as the crypt (dark blue green)
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Pearling

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Pothos suspended in the water column showing desired deficiencies from lack of nutrients in the water column (which keeps the discus happy)

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