Sand in pool after backwash/rinse

[wizzardz]

I have a Hayward 244T with top mount SP0714T valve. When I bought the place a couple years ago, I could tell the valve gasket was going out as I was having problem with water balance and leaking out to waste or recir.

I recently replaced the valve assembly since the gasket doesn't come separate. After running the pump with the new valve, the water cleared up nicely (even with all the pollen).

I decided to do a backwash and rinse. During the backwash the water in the backwash glass cleared up nicely. Once I switched it to rinse, the backwash glass half filled with sand. A good amount of sand was dumped in the pool as well, but stopped after a short bit.

I pulled the valve to check everything and all seemed fine. Ran another backwash and rinse with the same result.

Would cracked/broken laterals cause this? I was under the impression this would wash sand into the pool continually in filter setting.

Any ideas? TIA

[PoolDoc]

Cracked laterals can leak, and then stop, as the sand packs up.

But a more common cause is a misplaced air relief line -- it's easy to do, when you replace a top mount valve.

[BigDave]

Sorry to ask the obvious, but, is the pump off when you move the valve?

[wizzardz]

Yes, the pump is off when making changes. The air relief line adjustment seems to fit the symptoms - I need to find a diagram so I can determine what needs adjusting.

[BigDave]

Parts Diagrams:
Valve: http://www.hayward-pool.com/pdf/manuals/VariFloXLValve-SP0714T.pdf
Filter: http://www.hayward-pool.com/pdf/Parts%20Diagrams/Pro-Series-Top-Mount.pdf

I don't see an air relief line.

Another thought, is it possible that the multivalve has been disassembled and reassembled mis-oriented?

[PoolDoc]

I don't see an air relief line.

You're right -- my inexperience with top-mount filters is showing!

+ I don't see how you can mis-orient the valve, unless you mean with respect to the piping. Is that what you mean? . . . I have no idea what would happen if you hooked the pump discharge to the filter outlet, and hooked the outlet to the pool return!

+ Another possibility is that the filter was overfilled with sand . . .

+ And, yet another: if anything was done to INCREASE flow through the filter (bigger pump, removed pipe-line obstructions, etc), then sand will leave the filter during backwash, but a small amount will remain in the diffurser and return to the pool when normal flow is restored.

In both cases above, using the rinse position should remove that sand before it can enter the pool.

[BigDave]

What I tried to say was: if the six screws that hold the top valve assembly (handle, top, springs, seals, diverter) were to have been removed, the top of the valve removed (to change spider gasket?) and then put back rotated, the diverter (is that the right name) would be lining up to the wrong ports inside the multivalve. The drawing does look like it's keyed so not likely but it does look like it might be possible to install the handle rotated 180 degrees.

[wizzardz]

There wasn't much of a chance to get the orientation of the new valve wrong. Though I didn't work to try putting it on backwards, its the same orientation as the one that came off it.

Overfilled with sand is a consideration. I've been resisting pulling the rest of the top off because of the plumbing (much would have to be replaced). I think the fixed gasket would create a difference in pressure as the filter sees it (old pressure gauge was out as well, so can't tell a before/after pressure).

Sounds like I might have to bite the bullet and yank the top off the filter to check deeper.

One thing that's tough with this setup is that I don't really have a known good working state to start from. When we bought the house I could tell the old gasket was already bypassing to waste (water missing from pool) or recirc (tough time cleaning). Now that the valve/gasket has been replaced, there could be any number of issues that present when they wouldn't have before.

[PoolDoc]

Before you pull the valve (which is usually a pain on top mount filters), post the make / model of your pump. Note the the number on the electric motor are ONLY for the motor, and not the pump. Pump info is on the 'wet' part of the case.

The reason is, if your pump is oversized for your filter, the solution may be to throttle your pump back. There are several ways to do this.

It would also help if you can post pictures, by linking from Flickr, Photobucket, Picasa or by emailing them to poolforum@gmail.com

[wizzardz]

Its a Hayward 3007X10AZ pump married to a ST1102 1hp motor

[wizzardz]

Any feedback on if the above equipment is appropriately matched?

[PoolDoc]

In theory, that filter and pump are well matched. Unfortunately, most pool manufacturers tend to oversize pumps and undersize filters. Even though filters are rated higher than 15 gpm/sft, flows over that amount can wash sand out during backwash.

Your S244T filter has 3.14 sft, so it's 15 gpm/sft flow is only 47 GPM.

The SP3007x10 AZ will generate 45 gpm against 60' (or 26 psi) of dynamic head. Depending on your pools layout on the suction side, the dynamic head on simple pool is likely less that that, meaning the flow rate will be higher. One way to get an idea, is to look at the filter gauge when the filter is CLEAN. If it's less than 15 psi, your system is almost certainly running at more than 47 GPM, possibly a lot more.

Add to that the fact that the resistance to flow during backwash is likely lower than during normal operation . . . and there's a good chance you will lose sand during each backwash until the sand level is below standard.

As mentioned before, pictures would help us determine what a good solution for you might be.

[wizzardz]

Below are links to pics. I noticed the gauge is currently reading lower than when I replaced it (was about 15)

https://lh5.googleusercontent.com/-Dll6dK21UN4/U2RDN87t8YI/AAAAAAAAG-M/jUjUPBiJd60/s800/IMG_1152-ed.jpg

https://lh3.googleusercontent.com/-dgxpQdK_w6Q/U2RDOG4uztI/AAAAAAAAG-Q/ljVszks67oI/s600/IMG_1153ed.jpg


Let me know if there are other pics that would be helpful. Your feedback has been most helpful and makes sense.

I believe the psi change I mentioned above may have been before (15) and after (12) the backwash/rinse cycles.

From your description, its sounds I need a way to reduce the GPM rate. Any suggestions on how that may be accomplished? I'm guessing since the old gasket was partially blown out, it was reducing the flow by bypassing some to waste or recirc. (or the higher rate helped blow out the gasket)

thanks again

[wizzardz]

Decided to pull the top off the filter and check the laterals/sand/etc since the pool refused to clear up. Valve assembly pretty much lifted out easy enough...almost too easy.

https://lh4.googleusercontent.com/-XzlwBqtDlnE/U2RDPHP_wxI/AAAAAAAAG-c/VDHqDwuWKzc/s640/100_7129-ed.jpg

Besides the tube being broken, I pulled the rest of the old laterals and they were just crusted over and one was missing. Fortunately I had decided to get new laterals and sand. The filter is draining very slowly so I'll have to wait overnight before I start pulling the old sand.

Whats the best couplings to use on the PVC to allow easy disconnections in the future?

[CarlD]

I like to use quick connect unions or union ball-valves if I need to isolate it. So my low-drain and skimmer have union ball valves. But between my pump and filter is just unions, and between the filter and the salt cell are unions. Between the cell and the return is a union ball valve. And so on...

[PoolDoc]

Carl's right -- I'm working on a HOW-TO on that topic for you.

Meanwhile, this detail from the picture above answers the, "what's happended to my sand?" question, and perfectly illustrates what happens when pool dudes over-size pumps and under-size filters:

https://lh6.googleusercontent.com/-bqb3q05FhQ4/U2RDPgnr9FI/AAAAAAAAG-g/iyoh2HnvHzY/s640/100_7129-detail.jpg

[CarlD]

Yipes! That's about 10x as much as you should see!

Since I have an AG, I pull ALL the plumbing off to close and the way to do that is have quick-connect unions everywhere. Also, to isolate a section without having to plug returns, drains and the skimmer, ball valve unions make it faster and easier, say, for example, when you need to clean the pump's strainer basket, or clear SWCG protective screen. Or pull out your multi-valve!

[dcarlton]

Was going to chime in as this was actually the same problem I had today. Was getting sand in the pool after replacing XL valve and it working great for 12 hours. Went to backwash and really had no backwash pressure and really no rinse AND it was leaking out the waste port.

Thought is was the spider gasket (no), then a broken lateral (no) but like you discovered my pipe snapped at the lateral assembly. Replaced and back in business for now.