Adjusting Water Level

[Chad and Belinda]

The water level in the main tank is too high and we want to have the ability to adjust the level. the water goes into our overflows and down a stationary drain pipe. What do we need to do? We have 2 overflows, one on each side. Our last tank had something in the drain pipe that moved up and down to adjust the water level, just can't remember what it was. Does anyone know how to do this?

Any help is appreciated.

[Derek]

I usually just lower the standpipe. That will lower the level a bit but only as much as the slits in the overflow box.

[pbnj]

If your water-level is too high, that means your return pump is returning water faster than your overflows can drain.

Ideally, water-level is not something you want to be able to continually adjust. You want the water to be as close to the bottom of the weirs (overflow teeth/grooves/slits) as possible. This level will best skim the surface of the water and maximize your skimmer's performance.

You need to either replace your return pump with a smaller one or put some kind of valve (e.g., ball valve) to restrict/adjust the amount of flow. However, restricting a pump's flow is not really recommended.

Also, fyi, when you decrease the water-level in the tank, you will raise the water-level in the sump.

[prof]

Chad, is the higher water level causing problems? I also wonder if your standpipe is to tall. It should be below the lowest part of your weir.

Pbnj;

It does not matter how high the water is at the weir. Water is being pulled from the surface of the tank. I can see how you would be pulling a little more water from under the surface but that is going to happen after the surface is drawn into the overflow. In this situation you are just drawing a greater volume of water through the overflow.

Some return pumps are designed to be throttled back. You can always add a T to divert part of the water from the return pump back into the sump.

You will only raise the water in the sump until you remove some of the total water volume.

[pbnj]

It does not matter how high the water is at the weir. Water is being pulled from the surface of the tank. I can see how you would be pulling a little more water from under the surface but that is going to happen after the surface is drawn into the overflow.

Dave: Wouldn't that depend on exactly how high the water-level is compared to the weirs? If the water-level was somewhere between the teeth of the overflow, then yes, the height wouldn't impact the surface-skimming, but if the water was 1"-2" above the top of the weirs, then you wouldn't really be surface-skimming efficiently, correct?

You can always add a T to divert part of the water from the return pump back into the sump

Good idea. You could put a control valve on the pipe returning to the sump.

You will only raise the water in the sump until you remove some of the total water volume.

+1.

[prof]

I think once the water gets that high you are beyond any concerns of efficiency. Water is always trying to find its own level so the highest water (surface) is going to be the first to pass into the overflow. Think about it as an overflow without any teeth.

Once the water is 1-2"+ above the overflow you are still 'skimming' but it becomes more of a drain at that point.

So, yes, we are discussing the same thing

[Chad and Belinda]

Here is what we have: The water level is about 1 inch below the teeth of both overflows. One drain pipe has an elbow at the top with a hole in it (on the side). The other drain pipe is just an open pipe without a top of any kind. The open pipe stands about an inch higher than the other pipe but the water seems to be flowing into the pipes at the same level being that the water enters the open pipe right at the top and the water in the elbow is full up to the last 1/2 (top( of the elbow. If I cut the other pipe down (which I have the room) about an inch, would that hel?. Looks like that was the way it was befor we bought it. The problem is we have water coming down the front and back (very little but it leaves the water stain as well as the salt residue). This is worse with the top water gets more movement than usual, even when it is a small amout. This was never an issue with the prior owners. We did change the motor out. We have an 1850 gph pump that replaced a 1270 gph. However, the sump is built and had 2 external pumps, each with a ball valve. I was told that both running together was too much for the over flows. I cannot slow the internal pump we have now. However, I just bought a part and have fixed the old pump.

It seems to me the issue may be 1 pipe being higher than the other (I guess). I just didn't want to pull it out if I didn't have to.

What "T" are y'all talking about and what is it for?

I hope it makes sence, especially since y'all can't see what I'm talking about.

[Robb in Austin]

The T piece is on the return line. You would need to break into the return line, insert a T fitting and then run some more line off the side of the T back into the sump. The net effect is reduced flow back to the tank because some of it 'escapes' out the side port.