If you run separate filtration on each tank consider placing permanent pvc pipes for siphons mounted to the back racks or the stands. You dont have to drill them, just make a u shape of pvc and add a ball valve. Ive seen some cool manifold setups on this site for draining multiple tanks easily.
A local angelfish breeder I know has racks of 4 or 5 20g long tanks stacked vertically on top of each other. Each tank had the bottom glass drilled with a bulkhead and 1" standpipe. There was a sump for each bank of tanks. The return went to the top tank, which each tank overflowed down to the one below, all the way down to the sump... if that makes sense. So at least he had a few banks of isolated tanks if he had an issue.
When my old man bred fish for a living, he had 17 40b's and some other small tanks on racks. The whole thing ran on a central blower system. There was pvc running all over the basement with small air fittings and valves. Each tank ran on air driven sponge and or box filters. Water changes were done with a really long gravel vac that reached to the drain on the floor. Poor bastard refilled them all with 5 gal buckets... every week.
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