Peat filtration, KH, pH, CO2

[Faramir]

So. the KH/pH/CO2 relationship only holds if the buffer is all carbonate/bicarbonate.

But what about the acids? Does it assume that all the acid added is carbonic acid? Does adding peat lower the pH by lowering the KH, or not?

If not, then does this mean that CO2 estimates from KH/pH are going to be overestimates in aquaria using peat filtration?

[wetmanNY]

I've understood that this is the assumption. So I'm LWI (lurking with interest) in the hopes that a chemist can explain this for us.

[RTR]

Yes, the peat will reduce KH by absorbing some carbonate/bicarbonate (along with calcium/magnesium)- but that will in part read in the KH test.

And yes the peat will acidify the water via tannins and that will read in the pH test.

And yes the CO2 value derived by the pH/KH/CO2 tables will be magnified by the acid from the peat.

gsmolin did tests and reported them at Tom's Place some time back. They are in the Archives of the old boards, I'll have to see if I can dig the URLs out.

[Faramir]

Ta! I was thinking of setting up some jars of water with peat and without and finding out for myself, but if someone's already done it it will save me some wheel reinvention!

:)

[NGerdes]

Originally posted by RTR


And yes the CO2 value derived by the pH/KH/CO2 tables




Is there a website with one of these tables on it, and possibly some information on levels for certain plant growth. I am getting ready to plant a tank and my water has naturally high PH & KH and needed to know what levels of CO2 I will neet to inject.

[Tim Bo]

I wouldn't mind seeing that link too RTR...

There's a table at the following link for CO2 levels
http://www.thekrib.com/Plants/CO2/kh-ph-co2-chart.html