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fishgate
03/25/2012, 06:14 AM
I am having the hardest time balancing my new sump. Too much return flow and the sump gets low on water and micro bubbles come out of the return. Not enough return flow and the sump fills too high with water. It could be set ok and balanced and then a few hours later the sump is low again.

Is there some trick to this?

billdogg
03/25/2012, 06:32 AM
I'm not sure I understand the problem. The sump can only fill/empty as fast as the pump/DT return drains can function

fishgate
03/25/2012, 06:49 AM
Right - So if I have the return pump cranked up too high (via the ball valve) then the sump runs low (flows more than the overflow can empty so the return chamber in the sump gets low and lots of bubbles get returned as the pump sucks air).

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.

I occasionally get the balance pretty good and it runs for a day or so with no adjustment needed. But usually once the water level decreases due to evaporation, the balance is thrown off and I have to go through the whole ordeal again. I have no room for an ATO.

rovster
03/25/2012, 07:46 AM
Sounds like you don't have enough water in your system. Unless you're running a BEAST of a return, just add water to the sump until it stabilizes. This is all assuming your drain can handle your return.

Playa-1
03/25/2012, 07:51 AM
It sounds like you may be pumping more then your drain can handle or you may have some issues with the drain.

fishgate
03/25/2012, 07:59 AM
return pump = 700gph (not adjusted for head height), overflow = 300gph. I think one problem with the overflow is that it flows more water the higher the water level is in the tank. The skimmer teeth are around 1/2" - 3/4" under the water line. So if there is a lower water level, it flows slower (less), if there is a higher water level, it flows more. It is kind of a viscous cycle. If I up the return flow, the water level rises and the overflow drains faster since more of the teeth are further underwater hence more flow.

I'd love to just drill this tank and do away with the unreliable nature of HOB overflows but with it up and established, I don't see that happening. Ideally I'd like to bottom drill it.

I guess I could lower the skimmer into the water more for faster overall draining.

sirreal63
03/25/2012, 08:00 AM
Let's start with a list of the equipment involved. What is the pump and what overflow do you have? I am no good ad guessing. :)

fishgate
03/25/2012, 08:08 AM
Sorry -

HOB Overflow - EShopps PF-300 (300 gph)
Return Pump - Mag MD7 (700gph)
Head Height - ~3 feet

Big Dog
03/25/2012, 08:12 AM
I think the first 2 gph rates answer ur question? Return isn't large enough. That pump will do over 400gpm at that head.

fishgate
03/25/2012, 08:19 AM
Yes, but I have a ball valve and am reducing it to match the flow. I don't think you'd ever be able to get a perfect match so overspecing the pump and reducing flow is the best choice.

sirreal63
03/25/2012, 09:04 AM
A ball valve is a poor choice but it is what you have, you need to reduce the flow far enough to allow the 300gph overflow to operate properly, that could be as low as 250gph. It is a balancing act, too slow and air bubbles can collect at the top of the tube, too much and the overflow won't keep up. The ball valve doesn't allow very fine control, a gate valve would be the proper choice.

fishgate
03/25/2012, 09:17 AM
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? This overflow flows dramatically different rates depending on the amount of tooth slot below the water line. If you put it as low as possible in the water It will flow enough to remove the air bubble in the overflow tube. Anything less than that and the tube has varying amounts of air in it.

Look at the below video as I raise and lower the skimmer box.

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Playa-1
03/25/2012, 09:20 AM
What size tank are you using for the sump?

fishgate
03/25/2012, 09:30 AM
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.

http://www.drsfostersmith.com/images/Categoryimages/normal/p-32898-55651-fish-supply.jpg

sirreal63
03/25/2012, 09:48 AM
You set the level of the inside box to the level you want the water in the tank, then let it equalize. Slowly increase the pump out put so that any bubbles that accumulate flow through the tube. You may find it very hard to do with a ball valve, the adjustment is just not fine enough for that low gph of overflow. Too much flow, tank overflows, too little flow, bubbles accumulate and tank overflows. A ball valve is just not the right valve for fine adjustments, you may get there with it, but it won't be easy.

Playa-1
03/25/2012, 10:07 AM
I suspect that Jack is right on the gate valve option for your situation. It would also appear that you may be running your sump to low. I can't think of a good reason to only be running 10 to 12 gallons in that sump.

tomservo
03/25/2012, 10:09 AM
You could increase the capacity of that overflow by changing out that wimpy looking siphon tube with something bigger - I have made many an overflow tube with some PVC and 90 degree elbows. See if you can fit 1 1/4" or 1 1/2" in there and still have room for the water to flow up and around it. I would drill a small hole in the "arch" and glue in a cheap clear plastic check valve for starting the siphon (PVC glue).

One thing you need to make absolutely sure of is that your sump can hold all the water that will drain down in the event of a power failure!! I have seen guys that didn't consider this, power goes out for 5 minutes and saltwater everywhere, plus the pump is sucking air right after the power came back on and it pumped most of the water back into the tank.

fishgate
03/25/2012, 11:25 AM
You could increase the capacity of that overflow by changing out that wimpy looking siphon tube with something bigger - I have made many an overflow tube with some PVC and 90 degree elbows. See if you can fit 1 1/4" or 1 1/2" in there and still have room for the water to flow up and around it. I would drill a small hole in the "arch" and glue in a cheap clear plastic check valve for starting the siphon (PVC glue).

One thing you need to make absolutely sure of is that your sump can hold all the water that will drain down in the event of a power failure!! I have seen guys that didn't consider this, power goes out for 5 minutes and saltwater everywhere, plus the pump is sucking air right after the power came back on and it pumped most of the water back into the tank.

No I don't think the overflow can flow any more than it is. Even with full flow - that is with the skimmer part allowing as much water as it can over the edge, the siphon tube barely keeps up. It always has a bubble even if it is almost all the way down the tube. I could take the skimmer off and it wouldn't flow anymore.

Also that sump has a water level mark which is right at the sump level. It is designed to hold exactly as much as the water level that I am keeping it at. Take a look at the picture and notice that blue box right below the black sponge - that is the desired water level. It could hold a bit more, you could go up to the top of that baffle I suppose but that is only around a gallon or 2 more of capacity.

I did test breaking siphon and the tank can hold the sump water and I also turned off the pump and the sump can hold the tank water that would drain. Probably also why this sump has so much extra space. So I am covered there.

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

I'd love to bottom drill the tank but it is already set up and I really have no place to temporarily hold anything while the tank is being rebuilt. I do have a 120g FW tank that will eventually be re-purposed as SW. That one will be drilled and setup properly for a sump when the time comes.

Playa-1
03/25/2012, 12:02 PM
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. ;)

bravanc
03/25/2012, 03:02 PM
Looks like you have a 1" u tube and the tube to your sump is 1" too. You have created a full siphon and the 1" at full siphon can handle up to 960 gallon per hour tops. I would put a valve on the bottom of your over flow or input to your sump and adjust it there. You will be able to match the mag 7 flow.

fishgate
03/25/2012, 03:13 PM
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
03/25/2012, 07:50 PM
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
03/26/2012, 05:33 AM
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
03/26/2012, 07:07 AM
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
03/26/2012, 07:33 AM
.............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
03/26/2012, 08:20 AM
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
03/26/2012, 10:00 PM
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.

http://www.drsfostersmith.com/images/Categoryimages/normal/p-32898-55651-fish-supply.jpg

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
03/26/2012, 10:01 PM
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.

http://www.drsfostersmith.com/images/Categoryimages/normal/p-32898-55651-fish-supply.jpg

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
03/28/2012, 05:21 PM
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.