Inground Pump and Filter Question

[Jodester]

I have a 25,000 inground L-shaped vinyl pool with an attached spa. Currently, it runs with two 2.0 hp Hayward one-speed pumps (one for the pool, and one only for the spa), and we have a 30-inch Hayward 500-lb sand filter that's about 13 years old. We have lived in the house with this pool for 10 years. We have always noticed sand collecting at one part of the deep end of the pool, and fine sediment collecting on the stairs where our Ray-Vac doesn't go, and where there are two returns nearby. The multi-port valve on top of the filter has been getting harder and harder to turn, and I'm seeing sediment collect more quickly after vacuuming the stairs, so I figure it's time for a new filter. I was also figuring this would alleviate the sand problem (which we initially thought was coming from our patio pavers, but since we haven't applied sand in a couple of years I now think is coming from the filter).

In doing some research, a couple of things have come to light: 1) that our whole pump and filter system is too big for our pool, and 2) that despite our huge filter the pumps are still too strong for it, and that is what is causing the sand collection in the bottom of the pool (which we're only seeing in one spot because, I think, the bottom surface is not quite level and our Ray-Vac, which does pick up some of it, swishes any sand coming from the other returns around and this is where it lands). It occurred to me that while I think I may be seeing more sand lately, we have seen sand the entire time we have lived here. I had asked our pool company about the possibility of sand coming from the filter years ago, and they brushed it off, saying that if it were coming from the filter, we would see it "dripping" from the returns.

Any thoughts before we replace our filter with basically the same thing we already have?

-- Jody

[BigDave]

I would disassemble, clean, and inspect the multiport valve before writing it off. I would also inspect the laterals in the filter before replacing the filter. You'll have to remove the sand to inspect but you'd have to remove it anyway to replace the filter.

Perhaps someone else will comment on your sizing question.

[Jodester]

When I discussed removing the sand with our pool company, they advised against it, saying it's best to just leave it alone until it's time to replace the filter. He said the reason for this is because those filters tend to break when trying to replace the sand, and then you have to replace the filter anyway. He said it wouldn't be necessary to replace the sand if the water was staying clear. Perhaps that's the reason for such a large filter for our pool.

[BigDave]

I wasn't clear - sorry. I'm not advocating changing the sand but inspecting the laterals (which are buried at the bottom of the sand) before buying a new filter. It sounds like either your laterals may have been broken since the filter was installed or (as you surmize) the pump is pushing sand through them. The only way to know is to inspect. I see the laterals for Hayward S310T2 (2004 and prior) for as little as $5.00 on Amazon (not including shipping) where the S310T2 filter with multiport valve is more like $500.00. I would find a way to save the sand as I removed it and reuse it.

Here's the parts list for the S310T2 if that's the filter you have and here's the manual.

[Jodester]

No, you were clear -- but perhaps I wasn't. What I meant was the guy said the the act of manipulating the unit in order to remove the sand would damage the unit. He said they tend to crack when opening them up.

[Jodester]

Oh -- and regarding saving the sand -- I thought that after a number of years, the jagged edges of the grains of sand wore down and lost their effectiveness in trapping material. The sand in this unit is at least 13 years old (it has never been replaced). Do you still think it might be worth saving given that?

[mas985]

I agree with Dave, the pump is probably pushing sand out of the filter.

A simple fix would be to downsize the pump impeller. Do you know your current pump model#?

[Jodester]

Yes -- our filter is model S310T, a 30" filter that holds 500 pounds of sand. By the way, I was looking at its manual, and I can't get over how there is absolutely no mention of any regular maintenance such as changing the sand anywhere in the entire manual! I went online and found more generic instructions on changing sand, and it describes using a plastic cup to scoop out the sand to avoid damaging the laterals. I cannot imagine scooping out 500 POUNDS of sand with a plastic cup!

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Oops -- goofed on my last post. You were asking for the PUMP model, not the filter. Our pump is a Hayward C48M2N111.


EDIT by Moderator: 2 posts waiting in the queue were combined.