i have '3' diff plants in a vevor hydro system - 2 of the plants i have stable at a ph between 5.90/6.20 and the ec between 1.4-1.6- but with the 3rd plant which is a monster , the ph drops - i will set it today at 5.90/6.10, by tomm it will be down at 5.60/5.50 - since it is drinking at least a gallon per day, i will water, adding ph up, but would like to get it stable like the 2 other plants- any suggestion??