# Is it possible to raise pH in RO water without Na, Mg, K, Ca, S addition?

Maybe the question in the title is simple (=stupid) and the answer is 'simple No' but I have the urge to ask.

Some background, I have an aquarium which I use RO water and I use some portions of $$\ce{KHCO3, MgSO4, CaSO4}$$ to raise my GH and KH and in result, I get also an amount of $$\ce{K, Mg, S, Ca}$$ + (bi)carbonates in the water in a specific $$\pu{ppm}$$ quantity and ratio between them which I want to keep it stable.

Still, after the additions of the compounds above, I get something like 1 KH, 3 GH and pH of 6.4 but I need to raise it around 7.

Is there any other way to do it without another compound? (preferable no baking soda or soda ash)

Thanks!

• Try replace part of KHCO3 by K2CO3, keeping the same total amount of K. The needed ratio is best to determine experimentally. – Poutnik May 16 at 13:10
• Strontium carbonate, maybe? Not sure about the effects of $\ce{Sr^2+}$ on aquarium inhabitants... – Todd Minehardt May 16 at 23:38
• NH4OH, which is given off by aquarium wastes, anyway. – DrMoishe Pippik May 17 at 1:13
• Adding ammonium ions to an aquarium water is not good idea. – Poutnik May 17 at 4:18