Co2 levels registering too high - The Planted Tank Forum
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post #1 of 6 (permalink) Old 08-30-2019, 07:10 PM Thread Starter
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Smile Co2 levels registering too high

Hi everyone - New to this forum but looking for some help -

I have a 110ltr tank which is newly planted - 2 weeks and looking to add fish soon. All the water parameters are showing fine other than CO2 levels which are in the danger zone. - Ive been adding plant fertiliser. The plants seem great and growing nicely but im guessing need to lower the levels before I add fish (the exciting bit) - Do i just do a water change or is there an easier way to get these levels down

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post #2 of 6 (permalink) Old 08-30-2019, 07:15 PM
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Are you adding pressurized co2? If not I think you have co2 confused with something else.
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post #3 of 6 (permalink) Old 08-30-2019, 07:18 PM
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Are your fish gasping at the surface? If not, then you aren't in the danger zone.

pH drop would be a helpful piece of info to share.

Measure pH with no CO2 dissolved in water.
Measure pH after CO2 has been running for 2 hours.

Subtract the 2nd reading from the first reading. If you are at a full 1.0 - 1.3 drop you should be good to go. If you are less than that, you can add more CO2. If you more than that, your fish should be gasping at the surface meaning too much.

Yes, a water change will likely drop the CO2 levels. An air stone will too, moving filter outlet so its breaking the surface / splashing will too.

EDIT: Whoops... no fish in your tank LOL.

Well, if you are over the 1,3 drop in ph, that's too much for when you do get fish
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post #4 of 6 (permalink) Old 08-30-2019, 09:02 PM Thread Starter
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Readings attached

ive attached the readings - Im not putting anything in the tank at all other than fertilisers for the plants but nothing added today - Not putting in any Co2 so cant really measure a drop- I may be being remarkably thick by CO2 is carbon dioxide right???

Feel like a real newbie so sorry if my questions not relevant to this forum
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post #5 of 6 (permalink) Old 08-30-2019, 10:56 PM
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I don't know the Tetra kit, but they are undoubtedly arriving at the CO2 (yes, that's carbon dioxide) based upon the KH and pH readings, which would put your CO2 at 48ppm (unlikely). I think that you have to question the validity of the KH and/or pH readings. Without knowing anything about your tank, e.g.; substrate, additives, etc., my first choice would be to check the pH with another test kit (API or - recently seemingly better - Sera test kits) and, when you do, check both the tap and the tank water. Basically, I'm highly suspicious of the Tetra results but, again, I don't have any experience with Tetra ...other than using some of their other products when I was a kid.

You are probably still cycling the new tank. So, depending on the stage and activity, pH can fluctuate quite a bit.

If you want us to try to guess what may be going on, before you get [better] test kits, post the following info:

- What you are dosing (product and quantity) and how often?
- Substrate type?
- What is your filter setup?
- Cleaning regimen (filter and water change frequency and amount)?

Others may have other requests, so bear with us as we try to gain some focus.
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post #6 of 6 (permalink) Old 08-30-2019, 11:44 PM
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I'm with Deanna. If you aren't adding CO2, then there is something else lowering your pH.
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