Originally Posted by GreenIntentions
so your saying my ph will lower with co2 regardless of my kh? now is this going to go lower and lower every day until a wc or lower while on then gradual rise when off? with my plan i dont want to deal with all the pickiness of a high light system and have read that roughly 15ppm of co2 works ok with low light setups. with that being said will i still see a noticeable decrease of ph at 15ish ppm?
CO2 is a weak acid that will temporarily reduce pH. The higher your KH (carbonate hardness), the more CO2 required to reduce pH. The CO2 absorbed in the water will be released into the atmosphere once you stop injecting CO2, so your pH will slowly go back up at that point.
Many of us swing 1.0 pH or more, and some like @Greggz
have what I would consider high KH.
I think the point @Surf
was trying to make revolves around chelating agents. You don't need to understand anything other than chelates keep minerals (Fe in this case) in solution (your tank water) longer than without. Once the chelate unbinds from the Iron ion, the Iron can precipitate out of solution and sits on your substrate in an "unavailable" form. I put quotes around unavailable because I have not seen evidence that it cannot still be used by roots or attached to loose chelates.
Some chelating agents, such as EDTA, unbind quickly at higher pH, so we prefer
to use DTPA chelate when pH is over 7. At pH over 8, EDDHA is the best option, but it stains your water color pretty badly.