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Discussion Starter · #1 ·
Finally making the transition to 100% RO water, and now have sooo many options for water parameters I am a bit unsure of where I want to land.

Tank is a little high-tech 15 gallon set up with ADA Aquasoil. I have some picky plants that (I think) like low dKH and high Mg - Rotala macrandra mini and Rotala macrandra variegated as well as Ludwigia white.

I am remineralizing my water to 25 ppm Ca: 12.5 ppm Mg: 25 ppm K, with dKH of 1.8, and dGH of 6.4 using CaCl2, MgSO4 and KHCO3. I feel like I should have a higher dGH and Ca above 30, however, with my remineralization mix I already have Cl at 45 ppm and I am worried about Cl- toxicity. (S is very low at 16 ppm with that mix).

I know that Chloride from CaCl2 does not have the toxicity of Chlorine from our chlorinated water supply, however I have read some scientific articles that show toxic effects of build up of Cl- as low as 20ppm, and as low as 8 ppm for spawning fish (granted, the article was talking about spawning trout which I definitely will not have in my tank).

I think if I am going to increase Ca and Mg, I will buy some CaSO4 as toxicity levels for SO4 seem to be super high (unless you have anaerobic areas in your tank and Sulphate gets converted to toxic Sulphide which is a niggling worry looking at the four inch deep substrate at the back of my tank). Although not sure if I need to increase Ca and Mg???

Looking for 1) general advice, 2) your thoughts on Cl and SO4 toxicity and 3) What mix do you use?
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