Which pump do I need for 33' above ground?

[kenspam]

Over several days I've read much conflicting information and I really need to make a decision about my pump.

I have a 33' round above ground, 52" deep - I think it's around 27K gallons. Upon start-up, my pump is leaking badly and needs replacing. It appears to be a generic model and I can't even make out the HP. I have a Hayward Star-Clear 175 sf cartridge filter and intend to continue using it. Some sites say that I have to have a side discharge pump with the cartridge filter which I never had before. I'm planning on going with a Hayward Power-Flo Matrix 1.5 HP unless someone tells me otherwise.

Could I use a 1HP?

Thanks for any help.

[PoolDoc]

With a 175sft cartridge, you really don't want more than 40 GPM of flow. That's a little low for your pool, but it's better to match the pump to the filter, than to 'over-drive' the filter, causing damage AND poor filtration.

Here's the Power Matrix page:
http://www.hayward-pool.com/prd/Abov...1_14017__A.htm

As you can see, you really want the smallest of the three pumps. If you've had a larger pump, you probably need to get some new cartridges to use when you replace the pump. I'll put some links, below.

[kenspam]

Ok, so you're suggestion an even lower HP. Could you explain in very simple layman's terms what it means when it says my filter has 120GPM and 454LPM? I haven't been able to understand these figures, and even less now after your reply. Thanks for your help.

[PoolDoc]

In layman's terms, AG pool makers have been more-or-less lying about the capability of AG pool equipment, probably in order to 'sell sexy'.

They've developed, and gotten 'approved', bogus AG pump descriptions and HP ratings, and have gotten 'approval' for severely over-rating filters. I'm not sure why, but it may be so they can match them with over-sized pumps.

Horsepower, in US marketing, has "sex appeal". Filter square footage figures, which are complicated, don't. So pool salesmen market BIG pumps, to make the sale, but cut corners with little filters because pool buyers don't know the difference.

Bottom line: ACTUAL effective filter rates are the COMMERCIAL rates; residential rates -- even when "NSF Approved" -- are essentially bogus. Those rates (the real ones) are:

+ sand filters => 15 gpm/sft
+ DE filters => 2 gpm/sft
+ cartridge filters => .4 gpm/sft (0.375)

Your 175sft cartridge may have a bogus above-ground rate of 120 gpm, but the real rate is about 60 gpm. (My bad; I had a typo above!)

However, cartridge filters suffer from excessive flow more than sand or DE filters do.

With sand filters, if the pump's too big, you just blow the dirt through the sand, but don't usually damage the filter itself. With DE filters, the filter just stops up faster. With high head inground pumps, you can build up enough pressure to damage a DE filter, but probably not with AG pumps.

But, with sand filters, if you try to push too much flow into the filter, you collapse the pleats against each other. I'll try to post some pictures and other info, later

[kenspam]

Thanks for the explanation, no wonder I was so confused!

[PoolDoc]

Yeah, like many other industries, the pool business prefers a sexy and complex sales pitch (= fancy-shmancy lie) to plain statistics and honest explanations. Even if a company prefers to be honesty, it's hard for them to do so, since an honest description makes their product sound boring and out-of-date compared to junk being marketed with the latest 'sexy' lies.

The medical industry does exactly the same thing, when you get prescribed the latest patented drug @ $400/mo even when research shows the $10/mo generic is more effective. Only the scale is different: the pool biz rips people off for millions; the medical trade rips people off for trillions.

I have a friend who is an orthopedic surgeon of some skill. He's pointed out to me that you can tell doctors who always cut, even when therapy works as well or better, from doctors who recommend therapy first, and surgery if therapy fails . . . by which cars they drive. The 'top' orthopedic outfit in town reportedly won't schedule a 2nd appointment, without a commitment to surgery. Unsurprisingly that team's doctors tend toward Mercedes 500 models and the like.

In both industries there's a sort of Sgt Schulz ("I know NUTTING, I see NUTTING, I'm just doing my job!") collaboration between doctors, lawyers, gov't regulators, hospitals and drug suppliers on the one hand, and manufacturers, wholesalers, pool stores, builders, and the NSF on the other hand, that rips off victims without affording them a single clear 'bad guy' who's doing it to them.

PS: for everyone who has no idea who Sgt Schulz is, because they are under 50, and thus never saw Hogan's Heroes . . . Youtube to the rescue: http://www.youtube.com/watch?v=kp9BJxFHDYI