Above ground Pump...In Ground Pump????

Hi everybody, this only my second topic here at teh pool forum but I've learned quite alot just by reading through all the different forums. The pump in my in gound pool is currently working ok but it is old and I know soone rather than later I'm going to need to replace it... With this in mind I've started pricing pool pumps. My current pump is 1 HP and I plan on replacing it with a pump thathas the same power rating. As I looked around I noticed abover ground pumps are significantly cheaper than in ground pumps...why? Can I use an above ground pump in an inground pool? A pump is a pump...it's just an electric motor with the pump assembly attached to it. Why is an inground pump so much more expensive?

I don't know the answer to this but I will tell you that inground pumps are usually built a little more sturdily than AG pumps. I actually use an inground pump on my AG pool. Maybe my "bump" will get some further views and responses from someone who may better be able to answer this for you.

There are a couple of differences between IG and AG pumps.

IG pumps are all self-priming, however some AG pumps have this ability as well. It just depends on the design. This is important when putting an AG pump on a IG pool. It must have self-priming capability. AG pumps are usually installed with a flooded suction so priming is not an issue.

IG pumps use a diffuser while most AG pumps do not have a diffuser. A diffuser helps even out the radial load on an impeller. This means that the efficiency will be slightly higher and it may help extend the motor bearing lifetime.

From what I can tell, IG pumps use thicker more robust wet end designs where as AG pumps tend to have lighter plastic. So I would expect an IG pump to last longer than a AG pump but I have no proof of this.

Lastly, the head curves of AG pumps tend to be much lower than IG pumps for the same label HP. So you need to be careful choosing a pump with just the label HP because there is a wide range of pumps powers for a given label HP. You are much better off choosing a pump using the pump's head curve.

But with only an 8k pool, you really don't need a 1 HP or even a 3/4 HP pump. I have 1/2 HP pump on a 20k pool and it is more than enough. In fact, I put a two speed motor on the pump so I could run it on low speed most of the time.

Thanks, Mark.

To add to Mark's points. As a rough rule-of-thumb, IG pumps are usually rated in "full-rated" HP, but AG pumps are usually rated in "Up-rated" HP. I crudely figure an up-rated 1hp pump has, at most 2/3 the power and flow of a 1hp full-rated pump. That's really, really crude. From a pumping POV, 8k isn't a big pool. I run a 20K pool with a 1hp 2speed IG (full-rated) pump and pretty much run all the time at low speed--at most 1/3 HP, probably less, including my solar panels.

Thanks to all for the info, most helpful!!