siphon return issues

[klongo]

I'm just setting up a new AGA 180 with two corner overflows. I can't seem to get the siphon breaks to work properly and think I must be doing something wrong.

I have Stockmans going down to my sump and then have two 3/4 inch PVC pipes with LocLine spray fittings and eductors at the return. I drilled a 1/4" hole in the return PVC pipe just below the water level on the Stockman.

Now I have three problems:
1. A TREMENDOUS amount of air and microbubbles that I did not have before drilling these holes

2. When I shut off the electricity one of the siphon breaks never gets to be above water level? I can't figure out how that is happening.

3. When I remove the 90 degree fittings from the return PVC to the Loclines into the tank, I get immediate stop of the siphon (of course) but I'm still getting backflow into the tank -- Can't figure out from where.

At this point I'm thinking about plugging up the holes I've drilled and installing true union check valves into both return lines.

Any thoughts?

 

[flamron]

Don't use check valves - sure fire disaster. they will fail...I'm sure someone else will chime in on your other issues.

GL
Ron

 

[rustybucket145]

1/4" hole is pretty large.... 1/8" would have done the job.

2. When I shut off the electricity one of the siphon breaks never gets to be above water level? I can't figure out how that is happening.

You're gonna have to give a better reference than this... b/c what you're saying physically cannot happen. If the holes are drilled on the return line slightly below the water level.... you turn of the power.... siphon begins.... the water physically cannot remain the same depth.... if water is leaving the tank via siphon, the water level cannot remain the same.

Stockman--> What's a Stockman? Not familiar....

The air bubbles you are describing sound like your holes are pulling a venturi and sucking air into the return line. Either #1 your holes are too close to the surface or #2 your holes are too big.

Pic's worth a thousand..... post a pic and you'll get more help.

 

[AZDesertRat]

Keep your returns close to the surface and you do not need any drilled holes or check valves, both of which are bad ideas anyway.

A small amount of backsiphonage until the returns are exposed is normal and you should always leave that much room available in your sump at all times. Its not much, in my 100 gallon reef its less than 3 gallons which easily fits in my 30G sump.