# PH won’t drop with CO2 injection



## durb992000 (20 Oct 2022)

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.


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## xZaiox (20 Oct 2022)

durb992000 said:


> 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.


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## Zeus. (21 Oct 2022)

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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## Wookii (21 Oct 2022)

Zeus. said:


> What size is your tank?



About 2,200 litres - thats why he's struggling a bit! Reef——>Planted convert (400+ gallons)

As I posted in the above thread this morning, I doubt the Yidao reactors will be able to handle the injection rate to get a 1pH drop on a tank that size.

@durb992000 check out this thread - another Monster tank, almost the volume of yours, and also CO2 injected - it may offer some insights: (NO MORE) 2,000L High tech BEAST


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## Yugang (21 Oct 2022)

This is a fantastic tank, and I will follow with interest how the CO2 challenge will be solved. 

I would not hesitate and take a similar approach as      CO2 Spray Bar  . For this big tank with closed top  designed slightly differently so that the hardware is virtually invisible.

I would construct a box with an open bottom, the box mostly above the water surface and the bottom just a  centimeter below surface. It will be nearly invisible, use transparent plastic or glass. Fill the box with CO2, and with a good flow on the water / CO2 interface job done. Same concept as CO2 Spray Bar, and will be much easier than very complicated reactor designs for such a huge tank.

To test a prototype, 20 GBP materials costs (plastic and glue for making a box) and an afternoon work


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## xZaiox (21 Oct 2022)

Wookii said:


> About 2,200 litres - thats why he' struggling a bit!


Wow... Okay, yeah... that's going to take quite a lot of CO2


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## Yugang (21 Oct 2022)

xZaiox said:


> Wow... Okay, yeah... that's going to take quite a lot of CO2


Indeed, but it can be solved. The tank has a closed top, we can take advantage of that to limit the outgassing of CO2. I have been experimenting with that, not yet reported here on UKAPS, with promising results and greatly reduced CO2 consumption. There is really no need to fill our home with outgassed CO2 from such a huge tank.


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## Witcher (21 Oct 2022)

durb992000 said:


> 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.


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## durb992000 (22 Oct 2022)

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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## foxfish (22 Oct 2022)

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.


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## Wookii (22 Oct 2022)

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.


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## palcente (23 Oct 2022)

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


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## durb992000 (23 Oct 2022)

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?


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## Hufsa (23 Oct 2022)

durb992000 said:


> 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


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## Yugang (24 Oct 2022)

durb992000 said:


> 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 would build an oversized CO2 Spray Bar inside the sump. Invisible in the fishtank. With the right dimensions potentially a CO2 / water interface and CO2 absorption capacity that no reactor can match. For me a no brainer.

The function of a reactor is simply to create sufficient surface area between CO2 pockets and water, where absorption takes place. It is still not clear to me why we have all gone down the road of vertical bubble tubes, and not just created the simplest geometries to bring CO2 gas into contact with water.

EDIT:
As @foxfish suggests, one big 1.2 m 150 mm reactor with dedicated pump could also work, but requires experimentation and tuning to get all dimensions to work

You don't want a gas pocket in the top of the reactor, as that will reduce its capacity and more importantly create noise
You don't want bubbles to escape into the exit to the main tank, or mist.
You want bubbles of the correct size to remain in the moving water column until they dissolve, that requires probably a tunable bypass or tunable pump


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## Gorillastomp (25 Oct 2022)

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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## durb992000 (25 Oct 2022)

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


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## Yugang (26 Oct 2022)

If you consider the Spray Bar approach, let me know so I can help with some calculations to estimate what the dimensions should be. For the ramping up in the morning, the spray bar capacity should scale with the volume of the tank (plus sump). For steady state operation during the day, outgassing and some plant uptake, it should scale with roughly the surface area of the tank.  We would need to calculate if the area in the sump would be sufficient to place a spray bar system down there (I hope this is ok).

Whatever you choose, I would take two additional measures. Reduce losses in the sump, and perhaps reduce losses by sealing the top of the tank. This is a really big tank, so it will quickly pay back on CO2 expenses.


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## Andy Pierce (26 Oct 2022)

+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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## Yugang (26 Oct 2022)

Andy Pierce said:


> +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.



This is what I referred to before:


Yugang said:


> Indeed, but it can be solved. The tank has a closed top, we can take advantage of that to limit the outgassing of CO2. I have been experimenting with that, not yet reported here on UKAPS, with promising results and greatly reduced CO2 consumption. There is really no need to fill our home with outgassed CO2 from such a huge tank.



Would need to do some more testing, to find where 'too much sealed' starts to be disadvantageous. I had it nearly entirely closed, which obviously impacts the whole gas exchange from the tank, CO2, O2 and all others. For a big tank, I believe it is the only way to keep CO2 consumption reasonable.


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## Yugang (28 Oct 2022)

durb992000 said:


> I’m torn between bigger reactors or the CO2 spray bar.


I've got a new idea, that seems especially usefull for CO2 in big tanks. I need some time to work it out, do some simple calculations, and double check if I miss anyting. Will post when I believe it works for your tank.


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