Balance tanks

[Terry]

I’d like to equip my beach entry with a gutter and balance tank setup. I have a concrete drain going in, and the plan was for it to drain to the street, but I’d rather recirculate the water, if possible.

From what I understand, there are two types of pools these service. Pools that feed the filter system this way- the water level is above the level of the gutter and continually overflowing (when the system is on), and pools that have the gutter system in place to handle displaced water- which is what I’m looking at.

In the second system, how do you set it up to handle the variable input? It would seem that if I get the suction correct for when the pool is not overflowing (i.e. it is balanced for the static line input/output), that it would not be enough suction to handle when the pool is overflowing. Am I missing something?

Here is a diagram of a balance tank that I think could suit my purpose, sans the main drain connection. For the static line I would repurpose the auto fill line, I’m not crazy about the auto fill anyway. I also don’t understand how the how the gravity flow from the gutter works coming in to the bottom of the tank? Is there a backflow device that yields to low pressure?

 

[Bama Rambler]

It doesn't matter where you attach the gutter line to the tank at. The water will flow from the gutter up to the point that the level in the tank is equal to level in the gutter. The static line is going to keep the tank and pool levels equal. Since you gutter is only going to handle splashover, the static line will just keep returning the water to the pool. You could do the same thing by hooking the gutter to the static line and doing away with the balbnce tank. The pump would get hooked there too if you don't have the main drain. Having the balance tank prevents the pump from sucking air if the water level gets a little low. However if it gets below the static line the pump will drain the balance tank pretty quickly.

 

[Terry]

Ok, I’m trying to wrap my head around what you are saying, but I’m struggling a bit. Let me see if I’m understanding.

I have a couple questions about your first statements, but I really (!) like the idea of eliminating the balance tank so I’d like to explore that first.

You could do the same thing by hooking the gutter to the static line and doing away with the balbnce tank. The pump would get hooked there too if you don't have the main drain.

First, I do have a main drain, but it is plumbed to the pad. Kind of confused about the main drain’s function in all this, but if I don’t need to use it I don’t need to understand.

I think what you are saying here is that I would plumb the return that is currently being used for the autofill to the suction side of the pump- and I would tie the gutter drain into this line. Assuming I’m correct so far, how does this tie in occur? Is it a simple tee or wye, or is there something that keeps the water from backflowing into the gutter when the pump is off? The bottom of the gutter will be below the pool water level.

My autofill jet is about 6’ from the gutter discharge, and the autofill jet is about 12” below the waterline. In case any of that is pertinent.

 

[Bama Rambler]

Since you have a main drain that you can use as the pump suction feed, and are just using the gutter for splashover, I suggest that you just plumb the gutter drain straight back into the pool. Via static line or else.

Do you have any skimmers or other suction side ports?

 

[mas985]

To eliminate the tank, another option would be to plumb the gutter line (use large line) all the way down to the main drain at its lowest point. Sometimes this is done in lieu of SVRS because if the main drain is blocked, the water will get pulled out of the vent line and the pump will suck air removing the vacuum from the main drain.

However, the design is somewhat critical to work properly. You need a long column of water in the gutter line so when the pump turns on, it doesn't suck air so the attachment point needs to be at a positive pressure point which is as close to the drain as possible and at the lowest point. It helps if the main drain lines are large diameter. Also, when the pump is off, the water will refill to pool level in the gutter line. This way the debris that spills over the gutter line will be filtered out of the pool much like a massive skimmer.

But you might want to rethink having the gutter constantly overflow. That will remove debris from the pool a lot better and the gutter line will always be full although I would still plumb it like I suggested above just in case the water level drops.

 

[JasonLion]

The simplest setup is to plumb the overflow gutter back to the pool with it's own port. That eliminates the balance tank and any possible issues with the pump drawing air.

 

[mas985]

But then there is no skimming of the smaller debris that makes it past the gutter grates. There doesn't look to be any other skimmer line back to the pump. Also, there is very little risk of air getting into the pump with a vent line as this done in many pool builds. It is actually shown as an option in this document: http://www.cdph.ca.gov/HealthInfo/injvi ... azards.pdf

Also here: http://www.poolspanews.com/drain-entrap ... ution.aspx


But I think the best of both worlds is to treat the gutter as a massive skimmer and have it constantly overflowing. This will provide awesome skimming action similar to what is done in some commercial pools.

[EDIT] I changed my mind on the plumbing for the constant overflow setup. I would instead plumb a skimmer into the gutter so you can have basket that can easily be emptied and then plumb that into a header with independent valves for the skimmer and main drain. It should then work exactly the same as skimmer.

 

[Terry]

Where's the exploding head smiley? Just kidding, this is all very helpful. I'm kicking myself for not posting this question before as I've spent a tremendous amount of mental energy on it.

Bama, I do have 2 skimmers, plumbed individually back to the pad, along with the main drain plumbed to the pad. Very conventional pool, just playing now with this beach drain.

Mas, the diagram is not my pool, and the pool is already built. I think you might have been thinking it's under construction, as I'm not sure I'm ever getting to the lowest point of the main drain again. However, if I'm misinterpreting, please let me know!

The original design called for a drain at the edge of the beach to handle any splash out. Watching the kids in the pool last weekend I noticed that while the edges of the pool (typical tile/coping edges) handled the waves by bouncing the water back into the pool, the beach allowed the water to slide up and over. Design, flow of water and all that; I get it now, live and learn. Guess that’s why most have moved to the tanning ledges. Anyway, the kids were not being too crazy in the pool, and I got to thinking that I could potentially lose quite a bit of water if things got a bit on the wild side- as I'm sure is bound to happen. So, if I could find a way to recirculate the water, that would be preferable. And, although the pool is complete, the travertine pavers have not been set, nor has the drain been built so I have some options here.

Jason, just to make sure I understand before I get too excited about how easy this could be, when you say plumb the gutter back to the pool with its own port, you're saying I can connect the gutter drain directly to the return used for the autofill? My autofill return sits 12" below the water line, and is a normal 1.5" pvc pipe/eyeball connection. I think that should give me enough room, but I’ll run some numbers tonight.

I think where I’m having trouble, conceptually, is the whole water seeking its own level rule. The gutter will have standing water in it if I go this route, and as additional water enters the gutter, it will displace the water at the return jet/pool right away? Effectively, the water level in the gutter should not rise, unless the water level of the pool as a whole rises? Right? This is where I struggle, it seems like the water in the pool would provide resistance. I guess I understand that it doesn’t, but it sure feels like it should.

 

[mas985]

Sorry, I got the impression you were designing/building the pool so please ignore everything I said.

Also, water seeks it's own level because the pressure measured at the pipe connecting the two bodies of water is only dependent on the height of each body of water and not the width or the total weight of water. This is why pressure is measure in PSI (pounds per sq-in = water weight / water area, which is proportional to water height). When the height of one body of water increases, the pressure on that side of the pipe increases creating a pressure difference between the two bodies of water and water always flows from high pressure to low pressure.

 

[Bama Rambler]

With the skimmers and the MD you have a pretty good system to do what you're wanting. You can use the skimmers and MD to feed the pump and have surface skimming and just dump the gutter right back into the pool to handle the splashover.

 

[Terry]

Ok, I’m with you, the leap of faith is a little narrower now, so thank you for the explanation.

But now I’ve got to thinking about the standing water in the gutter. I have a 14’ length to traverse, so if I start with 0” at one end I should have 2-3” of water in the other end, depending on the slope. Pipe from the drain to the pool return will be about 6’. I don’t have the height to set it up so no water is left standing in the trough.

This water will only change over when the pool is in use, right? So maybe I don’t want it just sitting there getting stagnant? Stop me right here if I’m wrong, because this setup would certainly be the easiest, but I don’t want to create a maintenance issue having to periodically clean out the gutter, or introducing water that has been growing stuff for a week (or more) into my pool. Granted, we’re talking a small quantity of water, so maybe the cleaning of the trough is the biggest issue.

If I were to go back to Bama’s original suggestion of tapping the suction line in how would I do that? I’m thinking a 1.5” line back to the equip pad from the return jet, with the gutter line tied in to the 1.5” line?

With the return jet 12” below water level would there be risk of the pump pulling air once the gutter is sucked dry? If so, is there a way to plumb it to get around that? I'm fine with the gutter filling back up when the pump shuts off.

 

[mas985]

So is the height of the gutter low enough where you could raise the pool level such that you always had circulation through the gutter? Then you would not have to worry about sucking air. What is the gutter height relative to water height and deck level?

Otherwise, you will always have a risk of the pump drawing air from the gutter unless you can put a very deep loop, at least 6' down so the column of water can prevent the complete draining of the gutter pipe. This is pretty much what I had suggested before but it will be a lot of digging. Also, this still means the circulation is extremely slow so almost stagnant.

If you plumb a passive pipe straight back to the pool, then you may have dirt that collects in the pipe and when you have a lot people in the pool, it may get flushed out just at the wrong moment. Of course, you could manually flush it out by hand before swimming.

But how much water are you really losing through the gutter? Isn't it similar to a standard pool with splash out. Usually it isn't much.

 

[Terry]

The top edge of the beach sits 3” above my max water line (bottom of the overflow.) I don’t see a way to make it a continual overflow without lowering the beach, but if I’m missing something please correct me.

I believe I will lose more than a typical splash out due to the design. The slope of the beach allows the waves to flow up and over rather than hitting a vertical wall and bouncing back. I’ve only had several kids in the pool once, so I don’t have a lot of data, but I was surprised at the amount of water they moved. Maybe it was less than it appeared, but it seemed like quite a bit.

This loop/column of water, what is the purpose of it going so deep? Is it to create a certain volume of water, or to make it harder for the pump to empty it (more lift)? If it is volume, I’m wondering if I couldn’t create that with a small balance tank. Lots of details to work out there, but just thinking. And, I looked at the links you posted earlier, is this column open to the air or is the gutter plumbed into it?

 

[mas985]

This loop/column of water, what is the purpose of it going so deep? Is it to create a certain volume of water, or to make it harder for the pump to empty it (more lift)?

Remember when I described it was the height (or depth) of the water that determined the pressure? So when the vent pipe is connected to the pump plumbing, it is also connected to the pool water and will seek the level of the pool. Therefore, the depth of the pipe, measured from the surface of the pool, must be deep enough to prevent the pump from fully draining the pipe which will depend on where the pipe is connected. The closer to the pump, the longer the pipe, the closer to the pool, the shorter the pipe. Since you have a VS, the depth of the pipe is also dependent on the maximum speed that will be used on the pump. The faster the speed, the more suction the pump will create and the lower the pressure will be in the vent pipe. The hard part of course is creating the hole to put the pipe.

If it is volume, I’m wondering if I couldn't create that with a small balance tank. Lots of details to work out there, but just thinking.

It is the depth of water not the volume so the tank would eventually empty unless there was a constant supply of water, but then you wouldn't need the tank.

And, I looked at the links you posted earlier, is this column open to the air or is the gutter plumbed into it?

Yes, the pipe must be connected to the gutter which is essentially open to the air and even if it is filled with water, the surface of the gutter water is open to the air.


But back to the gutter and autofill idea. Do you have access to the autofill bucket? Most have a drain port where you could plumb in the gutter line although that may be too high. But you could tap into it at a lower spot too. It doesn't have to be tapped into the line. However, I would add a catch basin with a basket filter on the gutter drain so it isn't putting a lot of debris into the autofill bucket and you could then use a smaller pipe to the autofill.

 

[Bama Rambler]

I think an actual picture of the pool would help us visualize it better.

 

[Terry]

Let’s see if this helps:

The gutter will run around the beach, terminating just behind the rock. It’s about 6 feet from the rock (end of gutter) to the autofill bucket. The return for the autofill is directly in front of the autofill bucket, 12” below water level.

From the autofill to the equip pad is 22’.

The wooden platform is just there to allow me to navigate the back yard when it rains and floods the area- every 7 days, for the last 3 months.

I do not believe the autofill bucket will be low enough to tap into, but I would have to measure to know for sure. It probably could be lowered a couple inches.

Some thoughts I’m having, in no particular order- and possibly of no particular value:

If going for the deep pipe option, I would want to do it at the pool side anyway; too much activity over at the equip pad to dig, so glad to hear poolside is the shallower depth. I could tap the gutter into the autofill return line as it comes out of the pool wall (don’t have a clue if that would help) And in case you missed it, I’m fine with doing away with the autofill itself, or leaving it, whatever would help me the most.

The area behind the rock and around the autofill will be a planter. Since the deck is not in we have options here.

I can dig a hole for the pipe. Probably not 6’ though. Hoping 6' is the depth needed at the pump, and 2' is the depth needed pool side.

It is the depth of water not the volume so the tank would eventually empty unless there was a constant supply of water, but then you wouldn't need the tank.

This is where I’m getting confused, if I disconnect the autofill, and use the pipe from the return do I not have a constant supply of water? At least until the pool drops 12”? The gutter itself is not a constant supply of water, but as long as there is water in the line coming from the pool is air able to enter the line? And then when the pump shuts off, water backflows from the autofill line to the gutter, right? So the system is sealed again while the pump is off.

In addition to the gutter/autofill return the pump would also be fed with 2 skimmers and a main drain. Although I may alter the combo of skimmers/main drain I’m using, I don’t see a need to ever run just the gutter/autofill by itself. If the pump is able to pull from other sources, does that reduce its pull on the gutter?

Exploding head smiley needed again. Just sayin'

 

[mas985]

I do not believe the autofill bucket will be low enough to tap into, but I would have to measure to know for sure. It probably could be lowered a couple inches.

It looks plenty deep from the picture. It just needs to be deeper than the bottom of the gutter and I think you said before that the bottom of the gutter is 3" below the water line. Just open the fill bucket and look at the water level. As long as it is 3" above the bottom of the bucket, you are good to go. Since it is so close to the gutter, that might be the best/easiest solution. Dallas is dry and hot so I would not eliminate the fill bucket or you will be filling the pool by hand quite a bit. You just may need to clean it out now then for debris but is shouldn't be a lot. A 1" line from the gutter to the bucket should be sufficient, you just want a grate with a fine mesh to prevent the larger stuff from plugging the line.

If going for the deep pipe option, I would want to do it at the pool side anyway; too much activity over at the equip pad to dig, so glad to hear poolside is the shallower depth. I could tap the gutter into the autofill return line as it comes out of the pool wall (don’t have a clue if that would help) And in case you missed it, I’m fine with doing away with the autofill itself, or leaving it, whatever would help me the most.

Just to be clear it is the connection point to the existing plumbing system which determines the depth of the pipe and not the location of the loop itself. So if you plan on having the loop close to the pool, which is fine, it is the connection to the existing plumbing which is more important. So that means you will need to tap into either of the existing main drain or the skimmer lines. I would suggest the main drain line because it is less important than the skimmer lines and if you need to reduce the flow rate in the main drain line to raise the pressure in the vent line, there is little downside. Main drains have limited functionality. They should not be used to clean up the bottom of the pool as many on this forum have tried and regretted. And for circulation, the benefit is minor. Technically you could do away with the main drain all together and probably not notice the difference.

This is where I’m getting confused, if I disconnect the autofill, and use the pipe from the return do I not have a constant supply of water? At least until the pool drops 12”? The gutter itself is not a constant supply of water, but as long as there is water in the line coming from the pool is air able to enter the line? And then when the pump shuts off, water backflows from the autofill line to the gutter, right? So the system is sealed again while the pump is off.

Yes if you use the autofill you have a continuous supply of water but that still does not mean the tank won't run dry. If you pump water out of the tank faster than the fill line can refill it, it will still run dry. So it will be a balance act and you would definitely want a valve to control the flow out of the tank.

In addition to the gutter/autofill return the pump would also be fed with 2 skimmers and a main drain. Although I may alter the combo of skimmers/main drain I’m using, I don’t see a need to ever run just the gutter/autofill by itself. If the pump is able to pull from other sources, does that reduce its pull on the gutter?

Yes, that will help but again it depends on where you plan on tapping into the existing plumbing. This is why I suggested the main drain line because it is less important than all the other lines and the flow rate can be reduced at the pad with little effect to the pool.

Exploding head smiley needed again. Just sayin'

What about...

 

[Terry]

Ok, you may have understood this is what I was thinking, but what if I:

1) Turned the autofill return jet into a wall drain.
2) Ran a line from the gutter/wall drain back to the pad and valved it in there
3) At my pad, suction side, I’d then have, left to right: Spa, Gutter/Wall Drain, Skimmer, Skimmer, Main Drain.
4) Is there a way to handle the gutter/wall drain/line to pump interface (circled area) such that the chance of pulling air is reduced?

Drawn out:

If I set it up this way, when the valve at the equip is closed will the system work passively as we were discussing- when water enters the gutter, it will drain to the pool?

 

[mas985]

I understood what you were saying but I don't see the point of taking another line all the way back to the pad. Plus because of the varying degrees of suction that will normally occur with different pump settings and valve settings, you will always have the issue of drawing too much or too little from the bucket.

My suggestion is to just let the gutter drain back into the pool through the fill bucket. The bucket will capture any debris that gets past the gutter the grates. It just seems like a simpler and more fool proof method. Of course this means the water level in the gutter will be at the same level as the pool which might be a problem. But that would happen with all of the solutions.

 

[Terry]

The water level in the gutter matching the pool is not a problem, what I’m concerned about is water sitting in the gutter for an extended period of time. Spring, Fall- before it’s hot enough to swim, but after the water has started warming from the winter. I’d pretty much be setting myself up to have to maintain it somehow- flushing it out to keep it circulating, cleaning it out after it gets bad, something.

Making the beach low enough to make it a constantly recirculating gutter is possible, but would require coming up with a new design for the grate. Because the beach is an arc there are no commercially available trench drains. The plan is to pour a concrete drain and I have a machine shop with a waterjet that will cut the pavers into grates. The depth of the pavers, and the fact that they are travertine is what makes a recirculating gutter difficult- they would be constantly submerged if I lower the beach and kept the trench full to the top.

So, after a long drive home with lots of time to think about what you’re trying, diligently, to teach me, I think I’m finally getting it.

The deeper the loop (pipe), the greater the pressure; the point of this is that it makes it more difficult for the pump to pull the water through the lines, and the outcome is that the pump is not able to evacuate the pipe (gutter) completely? It will never clear all the water out of the gutter- at least at one time? I understand now what you meant by it slows the circulation to a virtually stagnant state.

Basically, I have 4 choices, then:

-Forget recirculating completely and have the gutter drain to the street.
-Connect the gutter drain to my autofill return and deal with water sitting in the gutter when the pool is not in use.
-Dig a very deep hole to make a plumbing loop and connect to the equipment.
-Make the gutter a constantly recirculating gutter by lowering flagstone on the beach and finding a new product to make the grates from.