Do Fertilizers/Easycarbo cause Ph to drop?

[Julian]

This morning when I added my KH2PO4/KNO3 (EI) and Easycarbo, the reading on my Ph controller dropped from 7.60 to 7.40 almost instantly, is this normal?

I'm trying to record a Ph profile so that I'm at 30ppm CO2 at lights on. I only use the Ph controller as a safety device - I set the controller to shut off when Ph drops any lower than 6.7 and aim for 6.85 using the needle valve on my regulator.

I'm just concerned that the fertilizer causing the Ph drop (and not CO2) will give me inaccurate CO2 measurements.

I know Ceg will say "just look at the plants and fish, let them be your guide" but I just want to understand the science behind it and have peace of mind that my controller isn't faulty as I've nuked my tank once before.

 

[Alastair]

Hi
Ferts and or easy carbo wont cause a drop in ph. Non that I have ever seen



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[dw1305]

Hi all,

This morning when I added my KH2PO4/KNO3 (EI) and Easycarbo, the reading on my Ph controller dropped from 7.60 to 7.40 almost instantly, is this normal?

It is the KH2PO4 (H2 and an H+ donor is an acid), you use it with K2HPO4 (which is the conjugate base K2 (an H+ ion acceptor)) to make phosphate buffer solutions.

Details of the ratios for differing pH values are here:
Potassium Phosphate Buffer

cheers Darrel