maybe an expert could chime in, but I believe the point of the air inlet is to break the siphon (because if it siphoned all the way down it would drain water too fast). Since the "Wye" fitting is above the lowest part of the U on the inside of the tank then I believe it should maintain a siphon in that part of the unit
If you don't have the air inlet side, it will draw air out the other end, along with all the water in the pipes. The middle portion will stay full of water this way, when the water spills in the intake side the level in the pipes will rise and just spill over the "Wye'd" pipe into the sump.
You shouldn't even need to touch the ball-valve. The center portion should always be full of water.
Once the level inside the pipes drops to the Wye it will stop going into the sump. Once the level in the tank drops below the inlet pipe, no more water is added and it will also stop going to the sump.
oh, yeah, i just realized that a second ago. your colored in drawing confirms my moment of enlightenment. i just thought about how it works and now it all makes perfect sense. so basically the ball valve is pretty useless
ok new questions...didn't really want to start a new topic because it relates to this
should I get a Mag Drive 12 (1200 GPH) or Mag Drive 18 (1800 GPH)?
with a 5' head height and 2 elbows and/or a spray bar (haven't figured that part out yet), what do you think the flow rate would be then and could this theoretically handle it? :-?
don't forget an air check valve in the loop going over the tank. If you don't get all the air out you run the risk of it losing siphon once the power is cut. monsterfishkeepers.com in the diy section has some 60 pages on building DIY overflows and different mods.
There was a link posted here that told how much flow you could get from different diameter standpipes, I can't find it :-?
Just go to MFK and type pvc overflow in the search box, hundreds of results come up :thumb:
I'm still looking...
yep, i added the checkvalve in. i think i'll attach it to a powerhead venturi to keep air bubbles out. will post some more pics whenever i get it running on the tank
i'm not sure what that drain calculator applies to? I think it applies to standard overflows and I'm betting these siphon types are somewhat less due to the number of elbows leading to more water resistance.
A check valve will malfunction eventually when used with a powerhead venturi. You only want air passing through the check valve. With a powerhead venturi, water will pass through the check valve and it will eventually get clogged. Then when air does build up in the overflow, the siphon breaks, the tank overflows, and someone will be mopping the floor. Believe me, I've tried it.
The powerhead venturi idea does work great without using a check valve. Just remove the check valve and fit the airline tubing right into that hole. You may have to open up the hole a little bit though. That's pretty much what I did and I haven't had any problems since.