Hi everyone,

I have very soft water, and my plants have shown Magnesium deficiencies in the past, so I have started dosing MgSO4. Now I want to start "dosing" calcium aswell.

So, I'm making my own GH builder. As Mg source, I have some EPSON salts (MgSO4.7H2O), as Ca source, I was thinking of using hydrated plaster (CaSO4.2H2O).

I'll mix 100g of plaster and 75 g of epson salts and mill it in a planetary mill. This would yield very fine, homogeneous powder with a ratio of aprox. 2:1 in GH degrees (Ca:Mg), if I've got the calculations right. Is this a good ratio?
Then, I would dose the powder directly in the water changes, 1 gram of the mix per 10 L of water = 3GH

Do you think that plaster is OK (the kind used in buildings)? What are other cheap sources i could use?
Should I add any other element to my GH mix?

PS, I also dose macros, Flourish and iron.

Thanks,
Bode.