Hey there, I'm about a year into this hydroponics stuff (see in this blog "http://www.hydroponicsonline.com/forums/showthread.php?t=4344). So far my biggest issue as far as water goes was volume. With only four Dutch buckets, and a 55 gallon drum "in ground", I'm having to add on average 25 gallons of
nutrient every 5 days. My last add, after 5 days of low 90's, was 40 gallons. I'm using two 1 gallon frozen jugs per day to keep the reservoir temp under 80 f. BUT.... tomatoes are still coming, easily over a hundred pounds of fruit so far. Hope that info helps...