I dont know if your diagram has enough detail. How big of a sump are you planning on using and what happens when the power goes out? 1 sump might not be a bad idea but it beter be sized properly for the 240 gallons of tank you'll have on the system.
its cm's, not inches, so the entire system would be a lot smaller than 240 gallons. There are overflows, the sump is about half the total size of all the tanks. the overflow is at the top of the tank so the content wont be able to drain completely
Is each level of tanks overflowing into the sump or does it overflow into the mid level and so on?
its all overflowing into the sump. there shouldn't be anything going back into the tanks witouth going trough the sump first
You might want to center the sump a bit more; and you might want to use the 32 mm pvc from each tank and then take those 4 lines (from each level) into a bigger pvc pipe leading to the sump (unless you're overflowing into the next level of tanks). 4 pvc pipes of the same size that all connect into one drain might cause a back up; 12 drains leading to one same sized drain will probably cause a bigger problem!
Thats actually a very good idea, i'll look around if i can find something thicker that goes into 32mm with a T fitting. I doubt 32mm's can't handle the flow though.
You may also want to use smaller pipe/tube from the sump through the pump back up into the tanks. Not sure exactly what size but you want the ability to move more water away than what your putting back in so to say. Depending on what pump you use, you may also want one more ball valve before it reaches any tanks in case you need to slow the flow entirely.
hmmn maybe.. I am using a 4000l/h pump(wich is about 1000 galons/h. The ball valves are there to regulate the flow, so it should be right, no?
and the ball valve, you're right, i was planning on that but forgot to add it to the picture :P