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Discussion Starter · #1 ·
I'm going to try and get the video up. But co2 diffuser under spray bar. Normally shoots up a column and then some into the current the rest to the top. I put in half a dozen holes into the spray bar that effectively elongates the amount of water the co2 bubbles travel through, or pushes them down then out into the water current also increasing time in the water column to dissolve.

It's fun to watch. Bumping up the co2 causes larger bubbles that go up faster, usually mostly wasted co2 in my opinion. Now as they climb up towards the bar you can see them hit the downward current and literally disappear if it doesnt get kicked dow and out of the downward column of water. The downward water and the upwards co2 bubbles seem to cancel out any odd currents. We'll see what happens with the current when co2 is off tonight when I get home.

Anyway, cheap, fun to watch, more co2. Thought I ought to share this.
 

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it doesn't look like you have much surface agitation. you need it to get more co2 into your water column.

diffusers are usually mounted on the opposite side of the tank, with the output traveling on the surface, hitting the opposite wall, flowing down the wall, then traveling back to the side with input and output. i have my filter return and reactor return on opposing corners to get a counter clockwise current. don't know how big your tank and filter are, but you want to get at least 10x turnover of water. my reactor pushes 210gph and my 2213 90? on a 20h.
 

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Discussion Starter · #3 ·
it doesn't look like you have much surface agitation. you need it to get more co2 into your water column.

diffusers are usually mounted on the opposite side of the tank, with the output traveling on the surface, hitting the opposite wall, flowing down the wall, then traveling back to the side with input and output. i have my filter return and reactor return on opposing corners to get a counter clockwise current. don't know how big your tank and filter are, but you want to get at least 10x turnover of water. my reactor pushes 210gph and my 2213 90? on a 20h.
Turn over is fine, Fluval 406 which is 380 gph on a 75 gallon. and the output pushes all water from 3 inches under the surface across (long ways across the tank) and then down at the end. I did have the diffuser on the intake side but there was no way that I am getting less CO2 dissolved now versus when I had it on the input side. There is like 2x or 3x (probably 2x right now but I could go higher) the amount of CO2 being pumped in yet zero co2 bubble collection on the surface. This is how I measure my CO2. or did until this. I can bump it up now, may actually need to use my checker now. or PH test this tank. I also added more holes in the direction I want the current to go right above the diffuser helping to make sure all this CO2 actually is pushed into the water column.

there is surface agitation, I added a couple of upward (about 30 degrees off of upward facing) holes on the spray bar to create the surface agitation. there wasn't any before. this was done months ago. But I don't know what that has to do with CO2 dissolving in the water column. I mean if I want Oxygen to transfer in and CO2 out, then yeah I want the agitation up. But again, pretty sure that just increases the amount of CO2 that dissipates into the atmosphere. I'm not talking about that right now.... I mean your reactor doesn't use surface agitation to put CO2 into the water column anyway so I'm not sure what your point was. If you want to clarify....

and 10x overturn of water? 10x what to be exact? in a minute? cause it's about that already.

So... unless I have literally miscomprehended all I have learned about what we want co2 to do, pretty sure this system is freaking awesome.
 

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It's an interesting set up, but with a 75G in the long run you are far better off with a reactor. No matter how you set up an in tank diffuser it's inefficient.

And CO2 bubbles on the surface doesn't tell you much. Get a good calibrated pH probe or monitor and learn how to get a good degassed reading. pH drop is easily the best way to measure CO2 saturation.

You do want good surface agitation. CO2 and O2 are not mutually exclusive, as you can have high levels of both.

Of course, much depends on your goals. If you have a lot of stems, then getting CO2 is much more important. If you have mostly swords like in the picture, then no need to max out CO2 and your system should work well.
 

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Discussion Starter · #5 · (Edited)
It's an interesting set up, but with a 75G in the long run you are far better off with a reactor. No matter how you set up an in tank diffuser it's inefficient.

And CO2 bubbles on the surface doesn't tell you much. Get a good calibrated pH probe or monitor and learn how to get a good degassed reading. pH drop is easily the best way to measure CO2 saturation.

You do want good surface agitation. CO2 and O2 are not mutually exclusive, as you can have high levels of both.

Of course, much depends on your goals. If you have a lot of stems, then getting CO2 is much more important. If you have mostly swords like in the picture, then no need to max out CO2 and your system should work well.
The swords of course took off. I have been trying to increase the CO2 for all the other plants. I have two swords that size. pretty sure I'm going to move one. But for now I just remove leaves as needed to get light to the smaller plants playing catch up.

The CO2 on the surface just tells... well it was just for the purposes of preference I suppose. But I wanted to share this for someone like me who is aiming more mid tech. High tech stuff but in a low tech amount. lol. I am calling it mid tech lately. But this allows me to double CO2 so far. I know I can go further. But I did this right before work this week so this weekend will be my test period. I will post more about how this goes then.

I will be doing the PH drops, I know how to do this stuff, I just haven't needed to. I was no where close before. Now that I am going to push this system I will be testing and monitoring. I would prefer not to buy more meters. But if it becomes a necessity I will. Right now I think I can dial it in and I also Highly doubt I will get to that 1.0 pH drop, but will be monitoring using that 1.0 pH drop method.

And as far as the agitation, I get they are not directly dependent on one another, I was just trying to figure out what Moke's point was about the surface agitation and how that would increase my CO2 in the water column as he/she implied. What they said makes sense if I am not using pressurized CO2 but I obviously am...
 

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this is what i was trying to say, "Having good gaseous exchange (increased surface agitation) means that CO2 levels taper off more steeply as CO2 saturation increases. This allows us to use higher injection rates without exceeding the lethal threshold. " (Dennis Wong, 2021).
 

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You have the right idea, but as mentioned you would get much better dissolution of you put the diffuser on the opposite end of the current where the flow can blow the bubbles down and around. The position its in now wastes a ton of CO2
1027546


As to the filter's 380 gph, that rating is with the filter running empty. Every canister except Hydors are rated that way. Which means irl you can count on about 50-60% of that flow rate. Just fyi
 

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there is surface agitation, I added a couple of upward (about 30 degrees off of upward facing) holes on the spray bar to create the surface agitation. there wasn't any before. this was done months ago. But I don't know what that has to do with CO2 dissolving in the water column. I mean if I want Oxygen to transfer in and CO2 out, then yeah I want the agitation up. But again, pretty sure that just increases the amount of CO2 that dissipates into the atmosphere. I'm not talking about that right now.... I mean your reactor doesn't use surface agitation to put CO2 into the water column anyway so I'm not sure what your point was. If you want to clarify....
I would suggest reading this article from 2hraquarist. It's a little nerdy, but once you get the concept, you'll be excited to see how high you can tune your CO2 without gassing your fish. The basic premise is that you want your CO2 to be at peak levels when the lights turn on. This means that your CO2 levels need to rise from 3ppm (normal degassed water) to 30+ppm in a couple of hours, and then NOT CONTINUE TO RISE once the lights come on. This makes a plateau in your CO2 levels, and they'll hold steady throughout the photoperiod. The way this is accomplished is by adding surface agitation.

Surface agitation in CO2 injected planted tanks - The 2Hr Aquarist

Take my tank for example. I run a pH monitor 24/7 that has logging capabilities. Take a look at the chart below, and check out the pH drop that I have in my tank. The plateau you see is the water offgassing any extra CO2, which protects my fish. If I had zero surface agitation in this tank, the fish would be dead halfway through the day.

 

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Discussion Starter · #9 · (Edited)
I would suggest reading this article from 2hraquarist. It's a little nerdy, but once you get the concept, you'll be excited to see how high you can tune your CO2 without gassing your fish. The basic premise is that you want your CO2 to be at peak levels when the lights turn on. This means that your CO2 levels need to rise from 3ppm (normal degassed water) to 30+ppm in a couple of hours, and then NOT CONTINUE TO RISE once the lights come on. This makes a plateau in your CO2 levels, and they'll hold steady throughout the photoperiod. The way this is accomplished is by adding surface agitation.

Surface agitation in CO2 injected planted tanks - The 2Hr Aquarist

Take my tank for example. I run a pH monitor 24/7 that has logging capabilities. Take a look at the chart below, and check out the pH drop that I have in my tank. The plateau you see is the water offgassing any extra CO2, which protects my fish. If I had zero surface agitation in this tank, the fish would be dead halfway through the day.

I will totally read that. But first thought is... plants take up CO2.... is this plataeu shown there because of a wave machine or some surface agitator that turns on at a certain time? otherwise this drop would be because of plant intake, no?

I haven't read this yet. But I will.


Edit... I read this graph as something else. not the pH. disregard what I put above in this post.
 

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Well, you're not wrong. This is a pH graph, which is a direct inverse of the amount of CO2 being injected. With or without plants, water can only hold so much CO2, and that amount is a combination of injection, consumption, and offgassing. The article will explain in far more detail than I could ever hope to.
 

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Discussion Starter · #11 ·
You have the right idea, but as mentioned you would get much better dissolution of you put the diffuser on the opposite end of the current where the flow can blow the bubbles down and around. The position its in now wastes a ton of CO2
View attachment 1027546

As to the filter's 380 gph, that rating is with the filter running empty. Every canister except Hydors are rated that way. Which means irl you can count on about 50-60% of that flow rate. Just fyi
Good to know on the flow rates. Either way my tank is wonderfully sparkling and clean. So Whatever it is, it's working. Also, how do we know that the 4x the tank size to GPH or whatever, think I reversed that, but how do we know it's not based of the manufacturer stats, the empty container stats? (Just blowing off steam at work. sorry not sorry for the facetiousness.

as far as the diffuser. I maintain that I can put in way more co2 and have it actually, visually dissolve in the water. I can watch larger bubbles that if done in the diagram above, would still go up to the surface and pop into the atmosphere. The mist, yes stays mostly in the water column.

However, with the system I have these same large bubbles visually dissolve and disappear. the mist is still carried off in the current; there is also more mist staying in the water column. So I am going to say this works better. Maybe I will move some things around in the tank and test it out. get some numbers so it's not my word vs the world apparently. lol.
 
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