Upgrade recommendations for replacing 14" Intex sand filter combo?

[PoolDoc]

Probably because AG pump/filter sizing is so 'flaky', the manufacturers usually do not make it easy to 'engineer' an AG pump filter combo.

Keep in mind, that the HP designations on AG pumps mean much, much less than you'd think: here's comparison table on the Hayward pumps:

https://www.hayward-pool.com/shop/en...ix-a-supowm--1



In general, bigger filters and smaller pumps are better. But, available equipment is better than unavailable equipment. A perfect match would probably be a 1 HP VS pump with a 21" filter, operating at 10 GPM for 8 hours per day, but backwashing at 12 - 15 GPM. However, such a system would probably cost $1,500 and have to be pieced together.

Everything is a compromise; nothing is fully optimal. But, I'm pretty sure the system listed above will work well, if throttled, and will be pretty economical, both to buy and to operate. And . . . it's available and serviceable.

[Pappy]

I did know that relating the HP rating of centrifugal pumps to actual performance is kinda like voodoo. Performance depends on how the pump is designed, intended flow and pressures, and on and on. And none of them are tested, rated and reported the same way. As far as availability, the Hayward S180T 18" filter is available today from Amazon, as is the Hayward SP1750 .5 HP pump. I also am in possession of an Intex pump that is rated at .75 HP, 4.8 A and 35 GPM (depending on which Intex source you look at). All the Hayward stuff should be plenty serviceable, shouldn't it? If a 1HP variable pump works on a 21" filter, would a .5 or .75 HP not work with the 18"? I'm almost kinda sorta nearly leaning toward hooking the 18" filter up to my Intex pump, and seeing how it works. Then deciding if I can go smaller, need to stay about the same, or go bigger and throttle. But then, a complete system is cleaner, much more convenient and less expensive - equipment wise - in the long run.

[PoolDoc]

"a complete system is cleaner, much more convenient and less expensive - equipment wise - in the long run."

. . . that was sorta my take on it . . . at least when the system is fairly competent, and that one seemed to be.

[Pappy]

One last question - I think. Is there any significant seasonal price difference in pump/filter equipment? End of season sales or the like? My problem isn't terrible and I could live with it till we close the pool for the winter. 10% savings is probably not worth the wait, 25% would be.

[PoolDoc]

Short answer? I don't know for sure, but I've never seen any evidence of that EXCEPT . . .

There is some times clearance on 'leftovers', but that puts you in a mix-n-match situation that can be tricky to work out and difficult to warranty.

Good luck!

[Pappy]

Since I like to tinker and "injuneer", and in the interest of keeping my darlin' wife a little happier, I've decided on this piece together system.

https://www.amazon.com/Hayward-S180T...keywords=S180T

and this pump

https://www.amazon.com/gp/product/B0...G42D8KUC&psc=1

I found some Hayward propaganda that claims the S180T "design flow" is 35 GPM. The
SP1592 is rated at 58 GPM @ 40' of head pressure. I decided to go with the two speed model so maybe I won't need to throttle on low. The two speed will use less electricity on low than a throttled single speed, and I think it'll make less noise. This system will cost about 20% more than the complete single speed system, but I think the complete system probably comes with the LX series pump, instead of the Matrix.

Is this valve

http://www.amazon.com/exec/obidos/AS...AI2/poolbooks/

any higher quality than this one?

https://www.amazon.com/gp/product/B0...KIKX0DER&psc=1

[PoolDoc]

My experience has been that the Hayward pool valves are lower grade than the Hayward industrial valves.

Will this make a practical difference to you? Dunno. What's going to matter is whether you can operate the valve. Larger ball valves can be 'stiff'. That's why I suggested the S-80 nipple as the attachment point, so you will have a firm strong connection to stand the torque of handle operation.

One caution: AG filter "design flow" is bogus, and has been for years. Sand filter 'efficiency' at particle removal INCREASES as flow rates DECREASE. Inground pools are rated at 15 GPM per sft of sand filter area. Above ground pools are rated at 20 gpm. An 18" filter is rated at 26 GPM for an in-ground pool, but up to 35 for an above-ground pool. The lower rating on that filter is possibly that it has a shallower sand bed, which lowers the rating. Unfortunately, for good filtration you need to run at 12 gpm/sft, or 22 gpm.

Why the difference? Just because . . . of marketing needs. There's no science or engineering behind it; filtration requirements on AG pools are actually MORE demanding than on IG pools.

So, do what you like. But 58 gpm is more than TWICE the optimal flow through that filter. Low speed probably won't be enough to backwash, but on high, you'll likely lose sand every time. And if you ever turn it on 'high' when it's set to filter . . . you'll clean the sand right into the pool!