Hey guys, trying this out . . one question about something I cant understand, the CalMag+ topoffs . . say I got a 20 gallon res and 3 days after a new batch of nutes, I am down 2 gallons of water. Do I ph the 2 gallons of RO water to 5.8, then add 3ml x 20 gallons reservoir = 60ml CalMag+ . . or is it 3ml x 2 gallons topoff?

In other words, with the CalMag+ topoffs do you add the 3 per mil for the total res size or just per gallon of RO water you are topping off with?

Thanks!