I am setting up my second system which is all IBC tanks. I have four GB. All of them are 1/2 IBC tanks, which is about 125 gallons each. I have not settled on a sumb tank size or how far down it would be. I am looking at index valves because I had a hard time with syphons on my first system.
My question is if it takes 20-30 minutes to fill and drain each GB, this will mean that each GB will be dry for 30x3= that is one and half hour of waiting till the index goes around to all the other GB's
As the system is grows and I add more GB, each one will add 30minutes to the waiting.
Does this make sense? Can the people who use index valves share with me their opinion?
My beds flood once per 12 hours or so. It's not a problem.
I have used timed flood and drain, but not an index valve. I used a hole drilled in the lower end of the stand pipe to control how long it took to drain the bed. Mine took a lot longer to drain than to fill.
Moe, depending on whether your sump can handle it...you don't have to wait until each bed is completely drained in order to fill the next one.
You can of course employ a quicker drain time. I'm going to copy and paste this 'answer' of mine from your other thread you started...where you posed a similar question...controlling your drain time is easy...
Your drain time will be determined by the size of the 'weep holes' that you drill in the bottom of your stand pipe. If 30 minutes is too long, go to the garage and grab a larger diameter drill bit
My beds fill in about 9 minutes (the fill time is determined by the size of your pump. I have a ball valve plumbed into the outlet side of my pump so that I can adjust (slow down, or speed up) the fill time. The "extra" water coming out of the ball valve just dumps right back into my fish tank...while the water from the grow bed(s) drains via gravity into my sump.
Unless you need to cycle quicker to accommodate a large fish ratio then you don't need to worry about a long cycle time. It's my understanding that the GBs can get by cycling a couple times a day.