U Tube Siphon- Joining two tanks together

[sly]

I recently completed a DIY project to join two tanks together. I used this to join my sump to my fuge. It requires no drilling, no mess and is a complete self regulating way to allow water to flow from one tank to another...
For those who haven't seen it, it's a U tube made out of PVC which will constantly siphon water from one tank to the other. When the water levels in both tanks are the same, the siphon will stop. As the water flows the siphon will flow again to equalize the levels once more. As long as this tube is installed the water levels between both tanks will be the same when measured from the top. This happens regardless of water flow. It can stop, start or even reverse directions... the water level will always be the same.
To do this I recommend 3/4 inch PVC for average water flow. You may need bigger or smaller depending on how much water you circulate, however don't go too big or you will accumulate bubbles in the tube which over time will break the siphon. You will need the materials listed. Join the PVC, elbows, and tee with good pipe cement. Don't forget to prime the PVC with purple cleaner/primer before you use the cement. Join the pieces together and screw in the barb fitting into the end of the tee. Attach your airline fitting and that's it. Be sure that the U tube is long enough to extend to the bottom of both tanks so that they will not pick up air bubbles (since there are fewer air bubbles on the bottom than on the top of a tank). I recommend cutting the bottom of the tube to an angle so that it will not accidentially seal if the tube actually hits the bottom of the tank. If the tube is too long and hits the bottom then water will not be able to flow through it.
Now set the U siphon tube between both tanks that you want to control water flow between. You may need to attach the tube to the tanks somehow... I just let mine rest on the top of my sump cushioned by a small piece of foam. Once in place, suck on the airline to draw water up into the siphon tube. Once you see water start to fill the airline, pinch it off and then stick something like a golf tee in the end to seal it off. That's it. Water will now flow from one tank to the other indefinitely, keeping the levels between both tanks the same.

 

[my way]

Sly, Do you drain from the DT to one of your tanks with the U Tube, then to the other tank and pump back to your DT? If you just connect 2 tanks with this setup you need anther U Tube with a pump connected to keep water flowing between the 2.
I use the exact same U Tube from my DT to my Fuge. When I set my tank up I had no room underneath for a fuge, So I made a stand for a 10 gallon tank to raise it to the same height as my 30 galon DT. I built an Overflow Box from a speciman collection box, dropped a small powerhead in it and pump through a homebuilt Skimmer and dump into the Fuge. It returns to the DT through the PVC U Tube

 

[sly]

No, I use an overflow to get water from my main tank. It then goes to a tee where most of the water goes to my wet/dry and my sump, while some of it goes to my refugium. My refugium then connects to my sump with a single U tube.
I didn't include how water actually gets to the tank in the first place because there are so many different ways people do it (manually pump it there, use overflows, overflow box, etc.).

 

[fender]

There is a post on reef central of a guy that connected his two tanks with a large clear acrylic "U" tube (was actually square) and was big enough for his fish to swim from one tank to another. :scared: Pretty cool.

 

[sly]

Wow! :scared: