In need of new pump, looking for advise!

I am looking to get a new pool pump (or just pump motor). I want to go with a 2 speed pump and have found a replaceable motor. But am not sure that is pump was not oversized from the beginning.
Some Background: This is what I currently have; an above ground about 16x32 oval (close to that, can not remember the exact measurements) about 13,000 gallons. Currently I have a Hayward sp -1575x1? (the zero might have faded off sp 1575x10) it is a magnetek 1 HP 115 volt 12Amp 3450 RPM motor, A hayward S160T sand filter, with 150# sand, an aquarite SWG and then a Jandy LX250 btu heater. It is 1.5 inch PVC. There is about 6 feet of PVC to pump, then 5 feet of PVC from filter through aquarite to heater and the 8 ft PVC back to pool. All PVC is almost on the same height off of the ground. Currently the motor is wired into a 3-way switch to control the motor from both the inside and outside the fence. Running off of a 20amp GFI circuit.

Question: I want to get a 2 speed pump was not sure about the size to get. I could the same size, but have read about how pumps are always oversized. So is this motor oversized for my pool? Also should I just get the motor, or for about 2 times the money get the whole pump? Right now the only thing that is wrong the current pump part is that there is a very small drip from the threaded in input line (I over tightened it at one point) It does not even leak all of the time.
This was my plan to get a just another motor same size, just 2 speed, and keep the pump part with new seals.
Any help/insight would be great. Thanks

River,

If you choose, I believe you could easily fix that leak. Is the pump housing cracked where the suction line enters?

I am by no means an expert, but personally, I am going to be using the pump and filter recommended on this page of www.poolsolutions.com. Specifically, this paragraph:

A combination that will work fairly well for almost ALL above ground pools -- regardless of pool size -- is a 1/2 HP Hayward "Super" pump (mfg. model #SP2600X5), a 22" Hayward "PRO" sand filter (mfg. model #SP220T), a Hayward 1.5" "Vari-Flo" multiport valve (mfg. model #SP071113), and a cord set (#SPX1550WA [25 ft long] or #SPX1250 [6 ft long]). 1999 list price on this combo is $764.00. Any pool dealer in the US or Canada can sell this combination to you. You'll also need hoses, connectors and . . . 250 pounds of filter sand. Make absolutely certain that the sand comes in bags that are factory labeled as filter sand, and make sure that the pump and filter have exactly the model numbers shown above. This combination can be used either as original equipment, or to replace what you've got now.

I've already purchased the filter, but I will be using my 1hp AG pump for a little while longer. I think it is on it's last leg anyway, so I'll likely replace it with Ben's recommended pump later this summer. I got the filter here for $247 shipped, which is easily more than $100 less than anywhere locally. It shipped out of Florida and arrived at my door two days later in pristine condition.

I did not specifically mention it but the pump motor has died and will not work I had it fixed the middle of last season and the local motor repair shop said it was on its last leg. Also the hayward S160T sand filter has a flow rate of 75 GPM. The crack in input threads of the pump filter basket is very small, not really an issue. Just wondered if it is better to replace the whole pump and not just the motor?

Look at the DYNII-N2-3/4HP (dynamo 2 speed 3/4 HP) pump I have the same filter w/ zeolite on 24 ft round above ground pool. It is almost silent on low and draws 2.6 amps. On high it vacumes well. If you don't have a heater it would probably be a good match. If you purchase this pump get some o-ring lube for the lid it's pretty tight. Congrates on your new filter!

We currently have an Astral pools 1hp pump that is on its last leg. I have been looking at the pump I mentioned above, along with three others.

Hayward Max-Flo Pool Pump ( Max Rated) | .5hp - HAYSP2800X5
Hayward Northstar Pool Pump Energy Efficient | .5hp - HAYSP4005NS
Hayward Power Flo II Above Ground Pool Pump | .5hp - SP1750

Money really isn't an issue, and I'm leaning toward the Northstar due to its claim of energy efficiency and quietness, but I'd like to get an opinion on the three pumps as well as the one recommended by Ben which is getting increasingly more difficult to find (always a concern when a product approaches the end of its life cycle).

HAYWARD SUPER PUMP MAX RATED 1/2 HP 115V

I haven't even considered looking at anything other than Hayward, but I suppose opening my options up a bit isn't a bad idea. I'll take a look at the Pentair 3/4 HP Dynamo 2 Speed Pump as you suggested.

I'd like to know what pump I'm going to be buying in case the Astral doesn't make it through the season. I guess I want to have my research done so I can pull the trigger quickly if needed.

I found a lot of great info here http://www.poolplaza.com/C-Pool-Pumps.html Each pool is different. They explain how to determine turn over rates, total dynamic head, maximum flo rates for the filter and how to read pump curves. Once you find out the particulars on your pool then you look over the pump curves and find out which pump best suits your needs. Too much power and you waste energy and your filter is less effective. Two speed pumps are great because they give you both efficiency and power when you need to backwash and vacuum.

Jennifer