I bought a house last August with a 24' x 52" above ground pool. The previous owners were morons, and their answer to every problem that arose was "Shock it!". To get an idea as to how bad it is, there isn't even a GFI outlet on the pool circuit, which I am correcting before opening this spring. They also didn't know how to use their filter, which was mismatched for the pool. The only two settings they ever used were filter and backwash, never waste or rinse.

When we got the pool, it was a green acid vat. There was so much algae it was incredible, and the pH was so low I couldn't get an accurate reading by any conventional method. I treated the algae with the store recommended brand, and due to my untrained newbieness and getting answers at a local chain store, I brought the pH up using soda ash. 37 pounds of soda ash. My alkalinity was through the roof. Surprisingly, for the rest of the summer the pool was pretty stable, needing little else other than chlorine and biweekly shock to stay swimmable. Alkalinity never dropped though, but neither did the pH.

After tons of research last summer, I learned a lot about pool chemistry (mostly from this site) and hardware, etc. I learned from my mistakes, and am now starting over.

In two weeks, I am doing a liner replacement (due to at least eight leaking patches) and hoping to swim a few days after that. I am also replacing the sand filter, which is a Waterco Hydron 19" 2.2cf filter. I can't get into the filter to replace the sand (it has a sealed collar), and one of the problems I had last year was sand in the bottom of the pool.

Also, the pump is leaking and will likely be replaced by the end of the summer. It is an Astral pool SEN1810, which is a 1hp pump. Double what I need.

So, today I just bought the recommended Hayward S220T (couldn't find an (SP220T) at www.onlinepoolsupply.net for $247.90 shipped. I couldn't find it cheaper anywhere else.

Anyway, in looking at pool pumps and filters (including the S220T), I see that it specifically says that it is for use with in-ground pools. Why is that? The same thing is true of the 1/2 HP Hayward "Super" pump (mfg. model #SP2600X5) recommended by this site. Why is that? Will I have any problems with using this filter on my above-ground pool? As an engineer, I can't see any reason why I would.

At any rate, I bought the S220T, and for the time being I will continue to use my Astral SENA 1hp pump for a little while longer, to be replaced by a Hayward half horse pump later. I know that the SP2600X5 pump is recommended, but is there any reason not to buy the cheaper 1/2 hp Hayward - SP1750 - Power Flo II Above Ground Pool Pump instead? It's about $100 less expensive than the SP2600X5.

Sorry for the book.