Balancing Sump

[fishgate]

I suspect that as long as the sump will hold the backflow when the power is off, Then you could run the water level considerably higher then it is. You may want to consider moving the the little blue mark that you're referring too.

I don't know about that, let me see if I can find the scraper. It is stuck on pretty tight. If I could move it, that would allow me to have a higher sump water level.

960gph? This is what the sump came with and Eshopps rates it at 300gph. I don't have any trouble matching the flow. I do think that a lot of people size down the overflow siphon tube for more consistency. It seems there is always a bubble in the tube.

I can get it just about max flow. The trouble is balancing between return and discharge. The overflow is just not designed well enough to be consistent within different water levels in the tank. So even minor variances throws the balance out. A quart evaporates and the sump is out of balance again. Usually it is on the side of the pump returning more water than the overflow will discharge. I can tell due to all the bubbles in the tank!

Ah well. This is my first sump. Best to learn how they work now so when I get a "big" tank I know what to expect.

 

[sirreal63]

I think maybe you are not grasping something, you have a return pump that can flow double the amount that your overflow can accept, and you have a valve that was designed to be on or off, you just cannot safely throttle the pump back enough with a ball valve, hence your frustration. A ball valve was never meant to be an adjustable valve, it works with higher flow in restricting, but you are trying to get it closed off enough to slow the flow to more than half of the pump's output, and a ball valve is not the right tool to do that with. If you did hit that magic position where it would restrict just enough, you may never get it there again.

A U-tube is the safest hang on overflow available, the CPR style is a flood waiting to happen. The problem you have is too much pump and not enough control. The overflow will match the pump only up to the point where you put more water into it than it can flow, you can have too little flow, but the only problem there is the bubbles can accumulate in the top of the tube. It is really that simple. You either need to use a smaller pump or change valve types.

 

[fishgate]

I think maybe you are not grasping something, you have a return pump that can flow double the amount that your overflow can accept, and you have a valve that was designed to be on or off, you just cannot safely throttle the pump back enough with a ball valve, hence your frustration. A ball valve was never meant to be an adjustable valve, it works with higher flow in restricting, but you are trying to get it closed off enough to slow the flow to more than half of the pump's output, and a ball valve is not the right tool to do that with. If you did hit that magic position where it would restrict just enough, you may never get it there again.

A U-tube is the safest hang on overflow available, the CPR style is a flood waiting to happen. The problem you have is too much pump and not enough control. The overflow will match the pump only up to the point where you put more water into it than it can flow, you can have too little flow, but the only problem there is the bubbles can accumulate in the top of the tube. It is really that simple. You either need to use a smaller pump or change valve types.

I just committed to buy a CPS - what is wrong with them?

Also the ball valve allows pretty good control. I may take your advice and re-plumb with a gate valve but for now, it seems to be mostly working.

Using a smaller pump is the same as cranking down the ball valve. When I do that, the water level in the sump rises.

The main problem I am having is this particular overflow is not self-policing. It changes its flow rate dramatically depending on the water level of the tank. So no matter what I do, what pump I have, or how the balance is currently set, it will change over time causing an imbalance again. I like the style of the CPS overrflow in that all of the intake slots are underwater all the time. This by itself should create consistency in flow through the overflow. The Eshopps overflow, with its skimmer teeth partially above and partially below the water creates a wholly unreliable flow rate.

 

[BigCountry74]

yeah +1 swap the ball valves out for gates. you can make micro adjustments with gates. balls are pretty much for on/off scenarios.

I run my Eshopps with the box (teeth) showing about 1/2". You should be able to adjust the box (raise it up and down) using the wing nuts. your sump should be reflecting your evap levels, not your DT.

also just to confirm, you do not have an air bubble or anything in the u-tube on the box do you? make sure that's a solid siphon.

 

[ErikS]

.............If I turn the pump return flow down, the sump overflow is greater than the return pump and the sump fills with too much water and reduces the tank water level.

Not possible. It is possible to pump more water than the overflow can handle, it is not possible to under pump (well from a flow perspective, there is an issue with keeping air out of the tube). When the overflow can handle the volume the sump will reach the level @ which it was designed to operate. Based on the picture that would be above the foam filter. It will raise up a bit more as the foam pad clogs.

..............I think I may just invest in another overflow. I like the CPR overflows they seem to be of a better design. ..........

Bad idea, horrible design. Any design that relys on an external device is subject to failure. More stories of CPR fails than you can shake a stick at.

I think the big question is where do I position the overflow skimmer? Do I put the bottom of the teeth at the level I want the water to remain at or do I raise it up? .................................

Correct the "skimmer box" as you call it determines the level of water in the tank. Set this to where you want the water level in the tank.

I think you're fighting an entirely different issue. The overflow, do you have any way for air to enter the pipe running down to the sump? If you don't you will have a cycle like I saw in the video...................

overflow fills -> siphon to sump -> no air -> flush -> siphon forms again, repeat.

This cycle causes the water in the "skimmer box" to do exactly what I saw in the video. It goes up as the lack of air slows down the siphon, it then goes down as the siphon forms & water flows faster. Up & down the cycle repeats.

Easy test, put a piece of airline in the tube running to the sump (note keep one end out of the tube, exposed to air).

Do a search on Durso, you'll need this device to allow the air & keep it quieter.

You can run a full siphon on the output to the sump but you'd need a 2nd pipe to the sump for emergencies (in case the main clogs). Search for Herbie or BeanAnimal. Run a full siphon (or any restriction for that matter) on a single line to the sump & you'll get a flood....................that's a when, not an if. Running check valves, restricting the overflow w/o a 2nd line, relying on devices to keep a siphon are all failures.................sooner or later they will fail, there are no exceptions.

 

[sirreal63]

Return the CPR, by design it fails as soon as the pump that removes air fails. The concept is great but it is a flawed design, air does accumulate in them, and whatever pump you use to keep it primed, will fail at some point, usually while you are away. What you have will work, but getting it adjusted with the ball valve on that slow of flow is just too hard. If you must get another device, get the u-tube that flows 600 gph, you have more margin for error, however what you have will work if set up properly.

Big Country and ErikS are telling you the truth.

 

[Voxboy]

It is an Eshopps RS-100 20 gallon sump. Its running volume is a little under 10 gallons. so 11-12 gallons of extra capacity.

Not familiar with this sump...but if that is the water line in blue...I would have to think that it would be the minimum level. I would definitely have my water line 3 or so inches above the sponge. The size of your overflow and the pump size based on head is good. If you insist on having your water level that low in the sump, you should have an ATO. That will run dry every day at that level. Raising your water level will also allow you to have more flow going through your sump eliminating air bubbles in your overflow.

 

[Voxboy]

It is an Eshopps RS-100 20 gallon sump. Its running volume is a little under 10 gallons. so 11-12 gallons of extra capacity.

Not familiar with this sump...but if that is the water line in blue...I would have to think that it would be the minimum level. I would definitely have my water line 3 or so inches above the sponge. The size of your overflow and the pump size based on head is good. If you insist on having your water level that low in the sump, you should have an ATO. That will run dry every day at that level. Raising your water level will also allow you to have more flow going through your sump eliminating air bubbles in your overflow tube.

 

[fishgate]

I figured it out!

I zip-tied some netting to the intake part of the overflow tube to keep critters out. Crap and algae had collected on the netting partially blocking the tube and creating inconsistent flow through the overflow tube.

I finally got fed up and took the tube out and that's when I saw it. So I cleaned it all up, put it back, and now the sump level is much easier to maintain consistency with.

I think it happened the other day when I scraped one of the really bad alga covered walls with a mag cleaner.