Edward

Hi,
is there a procedure, that can determine CO2 concentration in water at zero degree KH? The pH => KH table doesn't do it here.

My tanks have no issues with algae. Plants look great and fish are happy. Lemon Tetra (Hyphessobrycon Pulchripinnis) is breeding and raising fry without my intervention. The only problem I have is to control the CO2 level.

Details:

Black Neon Tetra
Bleeding Heart Tetra
Lemon Tetra
Cardinal Tetra

Hemianthus Callitrichoides
Glossostigma Elatinoides
Limnophilla Aromatica
Ludwigia Inclinata
Hydrocotyle Verticillata
Rotala Wallichii
Ludwigia Arcurata
Didiplis Diandra
Rotala Rotundifolia
Ludwigia Repens

RO water only

pH 4.1 - 5.2
TDS 150 - 250 uS
KH 0
NO3 5 - 20 ppm
PO4 0.25 - 1.00 ppm
K 10 ppm estimated
Ca2 10 - 20 ppm
Mg2 2.5 - 5.0 ppm
Fe TE (when Ludwigia Repens needs it)

K2SO4
KNO3
KH2PO4
MgSO4
TE (Fe EDTA 5%, Fe DTPA 2%, Mn 2%, Zn 0.4%, Cu 0.1%, B 1.3%, Mo 0.06%)

Mix of ratio
3.0 g CaSO4
1.0 g CaCl
1.5 g Soda
1.0 g MgSO4

It would be much easier if I could determine the CO2 concentration and keep it at 20 - 30 ppm.
Thank you,
Edward