why wont my overflows work!!!!!!

[foma2000]

when i set up my fug, i put it right next to the tank at the same level and had one 1/2" pvc pipe overflow conecting the two, the water would flow from the pump into the fuge then overflow to the tank. well i didn't feel safe with just 1 over flow so i built 3 overflows out of 3/4" pvc.
no matter what i do i can only get 1 of the overflows working. ill start all three of them, come back a cupple of hours later and only one will work. im really stumped! any ideas on why there not working. if i take 2 out and leave one then it will work, but when i put it with the other two it will stop. im really confused.

 

[BillyZ]

the first thing that comes to mind would be due to a lower flow rate, air bubbles are collecting in the tubes and breaking the siphon. When that happens in one, then the flow rate in the others increases and keeps the bubbles from collecting.

try double checking your PVC fittings to be sure there are no leaks. You could try drilling a small tap hole in the top of each, attaching a piece of airline tubing that connects to the air venturi of a PH. This could help keep the air from collecting.

 

[loganj]

I agree with BillyZ. Sounds like air is the culprit. You can get clear acrylic U tubes online pretty cheap. That would eliminate the problem and allow you to see if air was building up in the tube.

 

[fishfreek]

Other thing sounds like you have them at the exact same level. Since water will try to find a common level there isnt much natural syphon action going on there. If you lower the fuge by even a foot you will increase the overall syphon action. I also agree with the other suggestions. If you go with say a 1/2" overflow tube you might be better sucessful at multiple overflows. At the flow rate I am expecting you have a single tube will be able to process the flow just fine.

 

[foma2000]

thanks for the help. i did have to raise the fuge up a cupple of inches when i set it up. i dont know how im going to fix it. i like the idea of the air tap to the venturi, but i dont have a venturi ph so i think ill look for plans to make one.

 

[loganj]

You can buy a Maxi Jet 1200, which comes with a "venturi" attachment on the outflow side, for about $20.00. It will provide plenty of suction for air removal. You can buy the acrylic U tube for probably 1/2 of that.

 

[foma2000]

i dont see how the acrylic u tupe will actualy help the situation. the pvc pipes are glued shut, and i know that the seal is air tight.

 

[fishfreek]

The clear acrylic tube will allow you to see if there is indeed air collecting at the top that eventually leads to a break in the syphon.

 

[foma2000]

right. didn't think of that . im going to see if when i take out the overflow that works, the others kick in, if they do then i have nothing to wory about, otherwise, im going to go buy a u tube