I don't even have a tank with a sump, but for some reason I became fixated with trying to make an overflow siphon that would look presentable in a rimless tank. Here is my DIY Mame overflow ripoff attempt:
And here it is in action
I will do some more fiddling, because right now I need to pump about 100gph for the venturi to self-prime the siphon but the it maxes out at about 150gph. I would not trust such a small window of flow to not dump water all over my floor. I also need to cut down on some of that noise on the siphon break.
Here's how I made it:
I started with 1" acrylic tubing. To keep it from collapsing while bending I stuffed it with 3/4" silicon tubing. I then filled the tubing with sand to make it a little more rigid.
From there I would heat the tubing with a heat gun and carefully bend it. The tightest bend radius I could manage without the pipe getting creases was about 2.5" on center.
And here is is with all the main bends done:
I untied the end of the silicon tube and dumped out all the sand so I could pull it out. Well that is what I was hoping anyway. The tubing would not budge until I worked some mineral oil in there.
Here we go, finally got it out:
From here I started to drill a hole in the top of the loop for a siphon break. Of course, cracks started to form. In an attempt to salvage all the time I spent bending the tube, I heated up the pilot hole and stretched it out enough to fit 1/2" acrylic tubing. I glued the tubing in place with some number 4 cement, then reinforced it with a little bead of number 16 cement.
I had originally planned to have some airline feed through this half inch pipe up to the top of the siphon for priming like this:
But air bubbles liked sticking around just downstream of the opening of the tube, so I decided to feed it in the intake side.
On the intake side I had a problem with air getting dragged down the pipe. I found flaring the end like a blunderbuss helped with that.
From here I plan to work on:
a more elegant implementation of the priming tube
less return flow required to self prime
a better placement for the siphon break
tighter pipe bend radius or less deformation on the bend
I would appreciate any input on the design or advice on making acrylic bend to my will.