I need help with overflow

I have a 420 gph pump and a 300 gph overflow box (eshopps-300). There is about a 4' head with 2 90-degree elbows.

My flow is so slow, my u-tube is rarely full of water; it typically has an air pocket.

My ball valve is 45-50% open.

When I open it up, the water stages up. Any suggestions on how I can get more flow through?

 

A U tube? As in a HOB overflow?


The U tube should NEVER have air in it. You'll be mopping up water soon when the siphon breaks.

Could we please see some pictures and show/tell us what you're doing and what you want to accomplish?

 

A U tube? As in a HOB overflow?


The U tube should NEVER have air in it. You'll be mopping up water soon when the siphon breaks.

Could we please see some pictures and show/tell us what you're doing and what you want to accomplish?

I used to use A HOB production model overlfow years ago, and understand exactly how the work, drawbacks, tricks of the products, etc.

 

Could you please explain 'stages up' in a different way also? What are you referring to?

 

It's had an air gap in it for a year and a half. Power has failed a bunch, but it never loses siphion. Everytime I suck the air out, the bubble just returns.

By stagging up, I mean the water level rises higher in the tank to the point of overflowing.

I want to open up my ball valve completely, but can't without the tank overflowing.

 

The air pocket in the u-tube is affecting the flow; however, 300gph is not a very high flow rate. Also, with a 420gph return pump, you'll never open the valve completely without causing a flood. Your overflow rating will need to be higher than that of the pump to run full throttle.

 

Right, but with a 4 foot head and two 90s, don't you think flow is closer to the rating of the overflow?

Let's even say it's 75% it's rating at 315 gph, the valve being open to 50% restricts it 160 gph, right?

 

Your overflow rating of 300 is maximum theoretical value, realistically it's less then that. It's restricted by any possible interference with the water flow - your air bubble, piping, if you have 90 degree elbows it further restricts it. Is the overfow box itself always full of water? If it is, any other thoughts how the air is getting inside the U tube? I would deal with the bubble first.

 

Where is the ball valve located? Do you have photos of your arrangement? If not please describe every piece and location in both the overflow and retrun plumbing including line and fitting sizes, pump brand and model etc.

 

If air is making itg's way into the U tube- THAT's a problem.

You can use a piece of air hose, stick it from bottom to top of the U, and evacuate the air.- The flow should keep air OUT.

It can only get in 2 ways- it was there when you started- not likely right?
Or- you inside box- whatever you're using- is causing some air to get all the way down and into the intake of the U tube, it rises to the top and stops there b/c the flow isn't keeping it out.

by using mesh, the level of the inner box, etc., you can and need to keep the air bubbles out of the U tube- to mazximize it's flow.
What size is it? If it's 1" diameter U tube, and 1" diameter fro mthe outer box to the sump- it should flow more thatn 300gph.

Seriously, we need to keep the air out of your U tube. We can do this.
Watch the intake side, put some mesh or something that dissipates the air from going into the intake of the tube.