Testing Co2 Levels

Alright i thought that my 35g planted just had a problem with keeping up the C02 levels.

they were always at 16ppm. (5 drops)

i tested all the time and always the same thing.

well today i tested my 90g planted tank which has no C02 in it. and i got 16 ppm.

i tested the 10g that has no filter and/or fish which just holds my c02 bottles (keep them at 80C) and it came out 16 ppm.

im using the KH (carbonate hardness) set from aquarium pharmaceuticals.

after 5 drops of anything its always turns from blue to yellow.

is there something wrong with my water or something? im following the steps and i dont think its the kh bottle thats been damaged/mized up since i have 2 different bottles of it since i had bought one and then when i bought my 90g they gave it to me for free so how could i say no? B)

Can anyone help me? im dosing with c02, high lighting and flourish excel. I use Big Al's multi-purpose water conditioner after water changes.

Whats up with this?

Thanks for the future help guys and gals!


P.S: just for fun can you spot the keyhole cichlid in these pics?

I'd expect you to get the same KH in both tanks. After all I assume you are using the same water supply.

I think you are going slightly wrong in your testing though. to measure CO2 levels you have to relate your KH to your pH levels. Are you doing this or just testing the KH?
Get your pH and KH levels and check them against a chart shuch as this one:

http/www.thekrib.com/Plants/CO2/kh-ph-co2-chart.html


That will give you the CO2 level of the tank.

Hope that clears things up.

WK

by this chart i still only have 15ppm.

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