overflow issues

[markak15]

I have a 55 gal/15 gal sump that I've had set up for a few months now. I'm continually having problems with my overflow set up. I have a 700 gph overflow (not the U-tube kind, the other kind) that hooks up to some PVC (I forget the diameter but it's pretty big) and this goes down to my sump. There is a ball valve in the drain line. I'm running a Mag 5 pump.

When I have the ball valve in the drain line totally open, my tank overflows. If I turn it almost closed, so it's restricting the flow quite a bit, everything runs fine for a while. Over time though, i continually have problems and have to re-adjust the ball valve. Any ideas on WHY this is happening? I can't figure it out. I haven't had a flood yet but I think it is inevitable unless I do something. I'm not sure if I need smaller diameter PVC in the drain line? should I try a U-tube overflow box? anyone have a simple solution?

wishing I had drilled it,
mark

[Casey]

Humm I have never had a drain line with a ball valve on it,mine is inline right after my pump so I can restrict the flow,sounds like the pump is to strong for the overflow,maybe some of our plumbing experts will chime in.

[markak15]

I do have a ball valve in my return line too, right after the pump. I'm not sure why I put one in the drain line....I guess I could try restricting the flow from the pump.....

[Casey]

Yea open the drain line fully then adjust the flow from the pump so it doesnt pump to fast and overflow the tank and overflow.

[markak15]

I guess I learned my lesson...don't buy overflow boxes on ebay...they suck. I bought one of those smoky colored acrylic ones rated at "700 gph" and really wish I had just spent an extra $75 and got one that works.

[Casey]

Yea been there done that lesson learned the hard way.

[T469]

it may have something to do with back pressure, does the drain enter the sump underwater? i had to add a second exit point on mine with a t&some elbows to create a vent to let the overflow work properly, if the vent wasn't there the drain wouldn't keep up or it would take a while for the drain to get rid of the air and then it would continously flush, which now with a stockman and the vent in the line i get almost a constant level in the box, it just flucuates a little from the drain backpressure changing and the siphon of the drain increasing and decreasing from it.

so try bringing the discharge above the water level in the sump and see what happens, if that works then you'll just have to vent the drain line somewhere near the exit.

[markak15]

the drain line does empty into the sump below the water level. so you're saying that maybe the water coming down the drain line has to push it's way out against the pressure of the water already in the sump, and this could be slowing it down? so if the drain line stops before it goes below the water level in the sump, this could solve my problem?

[T469]

just have to try it, mine would push its way out with one big burp(bubble) and then would flow faster and would repeat until everything equalized. when i put the vent on the drain it cut down on the noise in the sump by letting the air bubbles out and also relieved the back pressure. i noticed this when my level in the sump got low and the overflow seemed to do better, now with the vent in the drain it keeps up fine with my mag 5 and probably handle more. the vent does dribble water so i have its exit barely above the sump water level and still have the main exit under water.

[Geoff]

could you post a pic of the sump and the overflow?

G~

[Casey]

If it dumps out above the water level it will splash more be to loud and evaporate more.

[T469]

Only my vent pipe discharges above the water level and only has a trickle of water, the main discharge is under water. the vent pipe is only 1/4" from the water and isn't enough to splash. works pretty well and cuts the noise pretty much to only small bubbles from the main discharge.

[markak15]

so you just put a T in the drain line right above the water level and attached a pipe? wouldn't just drilling a hole in the drain line above the water level have the same effect? i will try to post pics later...

[T469]

i tried a hole above the line but it kept spewing water and didn't help much so i cut the drain and left all fittings unglued so i could adjust put in a t with a bit of a stand pipe then 2 elbows and back down to the water. at first i had a t with a standpipe with a cap and a small hole, when i increased the flow of the pump it would spew what and make noise at the same time so i tried a t w/the elbows and it actually helped everything work much better. i get a restart, after pulling the plug on the pump, alot faster and the level in the boxes (inside and out) stay almost constant.

[T469]

oh i didn't say, but i cut the drain over the sump so if the fittings did happen to come off (even though they fit really tight) then the discharge would still hit the sump, just splash alot but wouldn't spill any water.