33 buckets with hydrocorn or granit took almost 80 gallons . They were 4.33 gallon donut filling buckets.
1200 gph pump is way over , you want a flow that takes all bucket to the same point of fill. Thats why you use a 3/4 inlet with 2 feed lines, this helps feed them all evenly.
1 pump to fill the buckets
1 pump to mix the res. before the bucket pump full
I used regular pumps but they give out in a year or two, the mag pump lasted 8 years and going.
Mag drive pumps only
I used a printer relay controler mod 74 about 25-85 from qkits ?
and used a program Relayrunner Never had a problem as long as you replace the computer battery every year. Its a fail safe system and worked at a few sites. About 40 years of total time on a few units , if you add up the growers I know. But there many more out there.
Note use a air pump in you main tank to keep the O2 levels high.
ONE last thing never more than 99 plants. A plant is one leaf with a root or a 8ft tree, thats de law