Add Calcium to your DI water

[DiverDude]

ok, noob question here: Isn't the idea of a RO/DI filter to get something as close to pure H20 as possible so that you can add salt to it to get 'seawater' which contains all these elements -but nothing else ?

In other words, doesn't the SALT add all the necessary trace elements ?

[mark]

no.

You'll find many salts if mixed as to their directions will get less than optimal levels of Ca and Mg to start. Plus corals like SPS will suck the Ca and alk out of the water column, reason people use CA reactors, kalk or dosing (manual or automatic).

[DiverDude]

I find that odd. Considering that reef salt is a very application-specific product, why don't they put appropriate amounts of Ca & Mg into the product then push frequent water changes ?

Just seems like a simple and efficient way of doing it.

[mark]

what should be and what is can be a little different. Many posts on supplementing.