Question on Circulation between two tanks

[rossb]

DM1 I have used the U tubes/overflow method to join two tanks of uneven heights. In my fresh water setup I have a raised tank and a lower pond. I pump water from the pond into the tank and use an overflow system to return the water. In my first set up I mounted a bulkhead fitting (drain) into an aqua-clear 300. The bottom of the drain is level with the water line in the upper tank. I had to play around a bit but i finally got it to work quite well. The secret...I use three U tubes. The most recent ones are made from 3/4 PVC and they work the best. If you do this you have to make sure the syphon tubes are at least 1 inch below the bottom of the drain. You also have to make sure you have an anti-syphon device on the pump lines...in case of power failure (I just drilled a hole in the pump line a bit above the water level).

Ohh and one more thing...if you have an airstone make sure it can't possibly get close to the U tubes. My fish kept knocking it and eventually the syphon stopped, and then a small flood...and then some spousal abuse ... and then the "if this ever happens again" speach.

If you want a picture let me know..