Overflow box problem

[brndfrb]

Well Sumphead was at my house tonight and we were trying to get the sump running. Well we got everything going and then realized the overflow box is not keeping up with the pump. It is an overflow box with a 1 inch drain. And i am using a sen 700 return pump. Now can i add a second U-Tube to the overflow box? Will this help? Maybe sumphead can jump in here and explain it better than i can. Even with the return pump throttled down and the drain wide open it still can't keep up with the return pump. Shouldn't it be the return pump trying to keep up with the overflow box? Any help would be great.

[WarOrks15]

well i had that problem so i put a ball valve on the retrun line. work great now i have it kicked back less then 1/8 of the way. what size tank do you have and what is the pump rated to move? you dont want so much water movement that your fish are painted to the walls of the tank.

[brndfrb]

I have a 65 gallon tank and the pump is rated to move 700 gallons per hour at 3 feet of head. Now that is about what i have 3 feet of head. I have a ball valve on the return and the inlet both. I have the ball valve on the pump kicked way down. Like stupid low. The overflow box just isn't supplying enough water IMO. It is supposedly reated for 800gph. Guess not. would the durso slow it down?

[reefrunner69]

Yes, you can add a second tube, one thing to keep in mind though...is if the water isn't running through both of the tubes quickly...one will trap air bubbles and move very little water. I would recommend , if your using a 1" tube now....that you go with two 3/4" tubes, if you can find them.

[brndfrb]

are you saying use a 3/4'' u-tube? Will that move more water? Do you think the durso is affecting the flow at all?

[sumphead]

IMO, FWIW, and any other acronym I can throw out there, The u tube is restricting the flow for some reason. As we saw the durso (which may reduce a little) was keeping up fine with whatever water was being thrown at it. Is this possible? The only thing I can come up with is for us to add another u tube, or perhaps the one you got is simply too small!?!?!

TIA (see there I go again with the acronyms)

R-

[brndfrb]

are you talking about the entire overflow box ronnie? Maybe i need a bigger one. I don't think it is the durso either. Just really satrting to make me upset. AHHHHHHH.

Ok sorry i had to do that but then a little screen popped up and told me to stop doing that.

Any more thoughts?

[reefrunner69]

Yes, the problem is the U tube has to go UP and OVER the tank wall before it can go DOWN the drain. That is what llimits the flow.

You have a few options...
1) Valve down your pump
2) Add a second U tube the same size as the one you have
3) remove the U tube you have and replace it with 2 u tubes of approximately 3/4 the size of the one your using
4) Replace the U tube you have with one that is approximately 1.5 times as big as the one your using.

HTH

[brndfrb]

so what would be the best option? I mean i guess i could always get a different overflow box if i really had to. The pump is valved down. alot. just wanted to see if there were any other options or ideas.

[reefrunner69]

You shoulden't need a new box, just more flow from one side to the other, unless I am in correct...which one is filling up, the tank or the rear box?

[brndfrb]

the tank is what is filling up. We put a durso in the overflow to quiet it. I mean the durso can handle alot more water it just isn't getting enough water. But it is the tank that is filling up.

Does the Durso have a small vent hole drilled in the top end cap? Sometimes it can get too much trapped air which will also slow the flow.

Cheers
Steve

[sumphead]

Yeah we drilled the durso. Basically because he is only running a pump rated at 700 gph He/we/I would like to see the pump run full flow without being inhibited by the ball valve at all. There seems to me no sense at all in reducing the pump. It would be like buying a Vette that performed like a Pinto. Besides it's not as if it were a MAG24 or something. Supposedly the overflow box was rated at 800gph which I find very hard to believe at 1". My suggestions is to either hit up Premium for a larger overflow or add another u-tube.

R-

[Brad]

The overflow box has two chambers...one in the tank and one outside the tank.
In scenario "A", the tank-side chamber is full (level with the tank water surface). The outside chamber stays low. The return pump continues to pump water into the tank leading to overflow of the tank. This situation, BTW, is one that you should have some sort of protection against (float switch), because it is what occurs should the siphon every clogs or stops (snail in the pipe syndrome).

In scenario "B", the tank-side chamber is lower than the water level of the tank, but the outside chamber fills with water. This would have the effect of slowing or stopping the siphon action, but is a different problem. As a rule, the outside chamber should always have a lower water level than the tank-side chamber. If the outside chamber fills up with water, it slows the siphon and moves you quickly to scenario "A".

Where to attack:

A: the siphon is not strong enough for some reason. It isn't pulling enough water. There may be air trapped in the siphon...or the tube may simply not be large enough to move the volume of water that the return pump is adding.

B: The outflow (to the sump) is not flowing fast enough to keep up with the siphon. The outflow hose could be airlocked or not large enough. Use a VERY large pipe for your outflow. Larger than the diametre of the hole in the bottom of the overflow box. I use plastic sump hose available at Home Depot.