Originally Posted by Hobgob
You could use I believe it's called a baffle pump (i belive) to put water back in the top aquarium. You can set up an drain for each tank to your house dwv system and have a pressure regulator dripping water back into each aquarium from your cold water essentially making a waterchange free aquarium. but then the gravel vac becomes hard again. Search up self changing aquarium on YouTube posted by eurajoey I believe is his name. Just set this up for each tank.
Miles and miles of plumbing. No! Absolutely not.
You can if you want but it isn't for me. I'll stick to the old fashioned method.
(Tap water alone isn't good enough for me)
The mix ratio using solenoid valves and circuitry would cost a considerable sum.
One tank perhaps, not for those who suffer from mts.
The principle is simple, I understand it and could easily build it. The cost to achieve functionality is beyond the scope of an average working mans wages.
Almost all systems are different. So that's many lines and manifolds each with a computer control and computing system with I/O valves and various switch points and pumps, cut offs emergency overflows etc etc. Really the idea past a mental sketch is silly. To actually produce such a system where the tank water parameters are different would be a feat of engineering worthy of front page news.