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PH won’t drop with CO2 injection

durb992000

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30 Aug 2022
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19
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Wales
Good evening all.
The tank is now set up and planted.
I have installed two yidao CO2 reactors. They have separate feeds from a 25kg CO2 bottle. Can someone please confirm the setup for these reactors. Currently I have:
  • dual feed from my CO2 regulator with solenoid that is connected to a ph monitor
  • CO2 lines going into each of the reactors
  • there is a clear vortex within each reactor. If I turn up the bubble rate of CO2, the water level drops inside the reactors
  • I have approximately 5000l/h pump feeding both reactors
  • the outlets from the reactors exit into the return pumps inlets

My concern is that the reading on my ph monitor doesn’t drop, regardless of how much CO2 seems to be leaving my gas bottle. Can anyone suggest something I can check or try?

I will take pictures/video tomorrow. I’ve also watched Zeus’ videos on how he setup his yidao reactors.

Thanks in advance.
 
My concern is that the reading on my ph monitor doesn’t drop, regardless of how much CO2 seems to be leaving my gas bottle. Can anyone suggest something I can check or try?
I've never used a reactor or a controller, so I can't comment on the setup of it, but the pH not dropping is a big red flag. Do you have any liquid pH test kits? Like API? I would use this to check whether or not the controller is/isn't displaying the correct pH. Otherwise, if gas is actively leaving your bottle, I would assume you either have a leak or are not injecting enough.
 
What size is your tank? I take it you have calibrated the pH controller with buffer solutions, so the controller/probe should be working fine. with large tanks and if you have high surface agitation you will need a high injection rate.

As @xZaiox suggested check for leaks, an old washing up bottle with a few drops of washing up liquid and some water, shake till full of bubbles and spurt bubbles out around fittings ( take care around 240V solenoids)
 
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Can anyone suggest something I can check or try?
What's your water hardness, especially dKH? Your water seems to have massive buffering capacity especially at that large size of tank and with 60kg of Seiryu stone which is made of carbonates, especially calcium carbonate. I think this is where your problem sits, not in general CO2 setup.
 
Thanks all.
I’m having some strange results from my PH probe. It measures the buffer solution correctly at 7. However, when I place my probe in the sump water it doesn’t really change from the 7 it was measuring when in the buffer solution. When I test the water next to the probe with a drop test, it measures 7.4. The Ph in the aquarium also measures 7.4. I tested in the aquarium and sump to see if there was any difference as it’s a remote sump system in a shed outside. DKh is measuring at 5.3.

I’ve taken a video of the sump system. I appreciate there is a fair bit of water movement and aeration which is likely to be adding to the problem. I’ve also added a picture to show that both sumps have plastic covers to reduce evaporation.

Video -
 

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Wow that is some set up for a planted tank!
Sumps are nice to hide equipment but when you push a lot of water through them it will very effectively gas off any C02.
Personally I would calm everything down and submerge any cascading water, you will still loose a lot of gas literally going down the drain (overflow) but the less water going down the drain the less gas you will loose.

Once an average planted tank has good plant growth, you will not need loads of additional biological filtration.
So a massive sump is not at all necessary but you could use the space to incorporate a big C02 reactor.
Something like a 1.2m 150mm pump powered reactor would work!
If it was my set up I would consider an enclosed loop pump for internal water movement, a slow through sump water flow with zero splashing and a sealed lid (even cling film) and if really necessary glass over the main tank.
 
That is indeed a serious sump system!

With regards to the Yidao reactors - maybe it’s just the video, as we only see them briefly, but I can’t see any bubbles or water movement inside them? I’d expect them to look like a soda stream of churning water with 5000 lph passing through them?

Also, whilst is difficult to judge anything from a bubble counter, I can see the flow of bubbles on those two, which tells me the injection rate likely isn’t high enough.
 
To me also that looks like very little gas injected given the size of your tank. My yidao leaked, there is a post about it somwhere, you could check for reactor leaks by submergin them fully, since they are standing in the water already. I think next to your tank these reactors look like toys, you may need a bucket sized reactor. That would be a cool DIY project:)
 
I’m finding that when I increase the CO2 and injection rate, even if only a little, it starts to create a fairly large air pocket at the top. This then causes buoyancy issues resulting in the reactors floating.
I have two large Skimz reactors, each holding about 8 litres of water. I wonder if I’d be better off adapting these? What are people’s thoughts on this?
 
I’m finding that when I increase the CO2 and injection rate, even if only a little, it starts to create a fairly large air pocket at the top.
For what its worth I run one Yidao on a 250 liter tank, its being powered by a canister filter rated at 2000LPH (but is probably less in reality).
With the surface agitation that im running right now the reactor doesnt have a chance to keep up with the injection rate and gets this gas build up very quickly as you mention.
Theres probably things I could do to make it perform better (besides the internal venturi I have already fitted), but I would be a little bit surprised/impressed if you can get two Yidao's to handle such a massive tank at almost ten times the size of mine.
I second the suggestions that you might need to go with something custom and scaled up to suit your tank, plus maybe minimize the off-gassing happening in the sump
 
You will need bigger reactors and more flow into them. Make yourself one with a 1inch inlet and outlet housing filter in the 20 inch long.

I say that because from your video your rate of bubble shouldnt be countable for this size of tank. Bubble counter are litterslly useless when you get this size of tank.

You will need bigger co2 tank aswell or you will have to change them quickly.

Edit: you will have to cover the sumps aswell to reduce degassing.
 
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Thanks for all of your thoughts, Rey are greatly appreciated.
I’m torn between bigger reactors or the CO2 spray bar.
I currently have 2 Skimz media reactors from my reef tank. They are about 7” in diameter by about 20” tall with 3/4” diameter inlet and outlets. Is there anyway of knowing whether these will suffice? I know I’d have to find some way of injecting the CO2 into it.
Thanks again
 
+1 on sealing the top of the tank. Sealing the top of the tank will also help with controlling evaporation and temperature.

If we wanted to go "whole tank CO2 spray bar" then by Henry's law, if you wanted a final concentration of around 30 ppm CO2 in the water, having a stable environment of 1% CO2 over the water would do the job. We do this with cellular tissue culture incubators where we maintain an environment of 5% CO2 (vs. the normal 0.04%). TC incubators have a CO2 controller system where you set the CO2 concentration you want, hook up to a CO2 tank, and off you go. Presumably similar control could be done to maintain a stable enriched 1% CO2 atmosphere above a large aquarium.
 
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