# PH unstable with CO2.



## jaycat (3 Feb 2009)

Hi, 

i have now started to inject co2 into the tank, there's no fish in there at the moment, they are still in the other tank they were moved to when the braace broke. This has given us the oppotunity to start co2.

However I'm having trouble with the PH, the tap water is 8.0,(these are taken with the API test kit) 
Started co2 yesterday at 2pm, at 9pm the PH had dropped to 7.4. CO2 off at 9pm.
10 am today PH still 7.4. 
1pm PH still 7.4 
CO2 started 2pm at 1 bubble every 3 seconds (not heavily planted yet)
At 3pm PH back up to 8.0
7pm PH still at 8.0.

My concern is, 1. is the normal, and 2 is this a stable enviroment for my fish? I'm not keen on the PH raising/falling by 0.6.

Could you all give me some insight please. Am I worrying for nothing? I don't want to reintroduce my fish until I'm sure everything's safe for them.

Thanks J


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## Themuleous (3 Feb 2009)

Hi Jay,

If anything this just shows the inaccuracies of test kits! 

Unless there are major changes in the position, flow rates or other things that might affect the diffusion of the CO2 then I would ignore this personally.  The pH will rise slightly during the lights on period due to the plants removing some of the CO2 but its nothing to worry about.  

Do you know about or have you got a drop checker with the 4dKH water in it?

Sam


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## jaycat (3 Feb 2009)

Hi, I've ordered one, I'm just waiting for it to arrive, then I'll set it up. Do you think it's safe for my fish to go back in there then?

Do you also run an extra airstone after the co2 has turned off? Maidenhead have advised me to do this.

Thanks J.


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## Ed Seeley (3 Feb 2009)

There's no need to aerate the water during lights off.  This is just unecessary expense IMHO.  Just turn off the CO2 half an hour or so before lights out.

pH fluctuations are perfectly normal when adding CO2.  They also do not affect the fish whatsoever.  The only way CO2 will affect the fish is you inject too much and they get overdosed on it and suffocate.  Keeping it at or below 30ppm will prevent this.  Remember pH will fluctuate with all the other factors in the tank too, not just CO2 level.


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## jaycat (3 Feb 2009)

Thanks so much, I was so worried it was going up and down.

 This is the first time I have ever used co2. At the moment I have it a 1 bubble every 3 seconds, but I hope to pick up more plants over the weekend so I will adjust accordingly. I will sit down with my partner and work out we have it right, hopefully the drop checker will be here soon too.

It's a 240l tank, so I guess with substrate and wood it's 200l.

Thanks again Themuleous and Ed.


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## Themuleous (4 Feb 2009)

No probs 

FYI - 1 bubble every 3 seconds wont be enough, I've got a 250lt and it must be running a 3 or 4 bubbles PER second! 

Sam


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