Supp dosing RO water

[Titus07]

Does anyone supp their RO water before a water change? I always seem low on MG after doing a water change. Using Instant Ocean mix.

[redfishsc]

Just use some magnesium chloride to raise your unused saltwater up to the desired level.

I just add in anything I am beefing up whenever I put the salt in the bucket with the water. For magnesium and calcium chloride I pre-dissolve the pellets in RO water first, but I don't know if that's really necessary.

[Randy Holmes-Farley]

I agree. If your salt mix is deficient in calcium or magnesium, as IO is, it is fine to boost the salt. I do myself. I add 70 ppm calcium and 150 ppm magnesium using Dowflake and MAG flake, respectively.

I add water then salt then magnesium then calcium to minimize precipitation of calcium carbonate. :)