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Regulating CO2

Robert Fletcher

Robert Fletcher

Member
Joined
18 Aug 2017
Messages
120
Location
Hinckley, Leicestershire
I am having some problems with CO2 regulation in the tank. I have an atomiser (40mm) diffuser into a 110 litre tank. Pressure of regulator is 3 Bar but I could raise this. The bubble counter is the type attached to the needle valve. Quite useless the bubbles are just streaming through.
Now to the problem. The gas is turned on at 06:30 and the drop counter is still very dark green at 08:30 when the light come on. By 15:30 the drop counter is Lime Green almost Yellow. It is as if it is just taking too long to get the gas in the water.
As for 2 or 3 bubbles per second I have long since given up on that. But would I be better with an external one. I don’t have a KH test kit I read where the chart can be easily misread and drop counters are better.
I welcome any suggestions. I do have a pollen diffuser but I understand they don’t work as well as an atomiser. It seemed to be OK just before Christmas but has gradually got worse. The atomiser looks clean.
Thanks Robert...
 
2 or 3 bubbles per second on a 110L tank is probably too low anyway.

Pics may help us to help you.

What may help (don't try them all at once!):
  • Changing your diffuser positioning
  • Reducing water surface movement
  • Improving water flow inside the tank
  • If you have an air pump, it should be off a bit before and while CO2 is on
  • Checking if the drop checker is clogged
  • Doing a PH profile
  • Starting CO2 injection sooner
  • Inline Diffuser/Reactor instead of an Atomizer
 
Thank you for that. No I won't do everything at once.:) I think I may have found the problem. After I wrote this it got me thinking. A few weeks ago I had to disconnect the cylinder temporarily. Reading my notes on the setup I had previously operated at 4 bar as apparently the atomisers work better at the high pressure. When I connected up again I set it to 3 bar. My tank has gradually become unstable. Algae started, excessive nitrate, water losing its sparkle. So I will see what different better CO2 diffusion does for that. Yes I am thinking about an inline reactor most people seem to prefer them.
Just noticed plants have just started to pearl again only the occasional bubble but some life is coming back. Thanks.
 
Also think about the time it takes for a drop checker to change colour, approx. 2 hours I think. So the colour you see shows the co2 level in the tank 2 hours previously.

It’s unlikely you will see it green at 08:30 after you have had co2 on for 2 hours since 06:30. Because it’s showing the level at 6:30!! Does that make sense??


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Patrick Crowley said:
Also think about the time it takes for a drop checker to change colour, approx. 2 hours I think. So the colour you see shows the co2 level in the tank 2 hours previously.
Click to expand...
No. A drop checker changes much quicker that that, as can be easily proved by breathing into your drop check. See here, you can change colour in minutes.
https://www.ukaps.org/forum/threads/how-to-check-your-drop-checker.43373/#post-465088

My drop checker change is probably about 1/2 hour or less, again easily proved by placing a "blue" drop checker into my tank many hours after CO2 has come one and hopefully settled. Within minutes of putting in the tank blue starts changing.

So drop checker is not that far behind actual CO2 levels.

What does take the time is raising the CO2 levels the water, especially when probably 90% of the gas just gasses off from the surface. Again see my CO2 curves linked to in my post above, for why that is.
 
Thanks to everyone. I am sure the problem was the pressure too low. Back to 4 bar and the BC response time is about an hour.
I must apologize that I may not have made things clear. I have had this CO2 setup since Sept and it worked then. It was the resetting of the regulator tat seems to have caused the problem. But all this takes time to discover whilst the tank is becoming toxic. When I mentioned the drops it was to say I do not count drops as I find this useless the reason I even mentioned this is because I thought someone would.
Thanks.
 
Have you thought about flow /distribution of the CO2 as this can have an equally drastic impact.
 
Yes I have a good flow throughout the whole of the tank. I made sure of this way before I went to CO2 injection. I was not looking at a setup solution that I have worked on but something that had changed. Atomisers requite higher pressure and 4 bar is best. I am confident I have fixed any gas problem.
 
ian_m said:
No. A drop checker changes much quicker that that, as can be easily proved by breathing into your drop check. See here, you can change colour in minutes.
https://www.ukaps.org/forum/threads/how-to-check-your-drop-checker.43373/#post-465088

My drop checker change is probably about 1/2 hour or less, again easily proved by placing a "blue" drop checker into my tank many hours after CO2 has come one and hopefully settled. Within minutes of putting in the tank blue starts changing.

So drop checker is not that far behind actual CO2 levels.

What does take the time is raising the CO2 levels the water, especially when probably 90% of the gas just gasses off from the surface. Again see my CO2 curves linked to in my post above, for why that is.
Click to expand...

Really interesting reading Ian, thank you!


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Robert Fletcher said:
Yes I have a good flow throughout the whole of the tank. I made sure of this way before I went to CO2 injection. I was not looking at a setup solution that I have worked on but something that had changed. Atomisers requite higher pressure and 4 bar is best. I am confident I have fixed any gas problem.
Click to expand...

I think diffusers are different then as Mine runs at just 2bar, perfectly well. It’s a rhinno bazooka 80mm diffuser. I can raise it up to 4, but what is the benefit?
 
The problem with some ceramic type diffusers is they require higher pressure on the low side of the regulator. The ceramic provides a quite high resistance and backs the pressure up, even while running. You'll notice that when you switch on, the bubbles stream on the counter but still nothing coming out of the diffuser yet. Then once the diffuser is bubbling away, the stream of bubbles in the counter slows. This is where you use the needle valve to set it perfect - up or down.

Basically, the trick is to have more pressure behind the needle valve than you need, then wind it back. If your needle valve is all the way open and you're getting 3bps in the counter, you need to up the low pressure side on the reg. Get it so its giving 8-10 bps (basically more than you can count), then wind back the fine tune to get 3, or 4, or 5bps. This leaves you 3-5 bps on the needle valve if you need to increase it without having to muck around with the low pressure side valve all the time.
 
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