When you feed your plants with RO water you need CalMag Plus to put back minerals the RO process removes but the plant still needs.

Epsom salt is to treat magnesium immobile.
Zandor Reviewed by Zandor on . epson salt, cal-mag question? hey people im a first time grower i used a hydro system but got 7 males outta 7 plants...grrrrrrrrrrrrrrrrrr my question is whats the deal with this epson salt and calmag? what are thes and where do i buy them??? next time im going to use pots!!!! Rating: 5