pump size questions

[joshhighley]

I'm trying to get an idea of pump size for a 15'x30'x54" Sharkline Matrix. I've found various gallons amounts for this size, from 12000 up to 15000. Worse case, at 15000 and 8 hour turnover, that's a little over 31gpm. My pump will be located close to the skimmer and return, so my research suggests a 1HP pump should have way more than enough capacity.

However, around these forums I see people with similar sized pools, if not the same exact pool, but they have a 2HP pump. I understand every install is different, but this seems like a really big difference. Am I missing something or do people have pumps that are way oversized?

Also, after some quick online shopping, I've noticed that 1HP pumps don't seem to come in variable-speed; 2-speed seems to be the best I can find. Am I wrong about this or is the VS efficiency gains for a 1HP just not worth the extra cost? Efficiency-wise, would I be better to go to a higher HP to get a VS pump instead of a 2-speed 1HP?

 

[VikingPoolMan]

I don't know much about above ground pools but I don't see why you would need a 2HP pump for a pool like that....1HP would work fine. What size filter do you have? What size plumbing? If you're looking for a 1HP variable pool motor, why not use an impower? I've installed many and most people are happy with the product.

I'm trying to get an idea of pump size for a 15'x30'x54" Sharkline Matrix. I've found various gallons amounts for this size, from 12000 up to 15000. Worse case, at 15000 and 8 hour turnover, that's a little over 31gpm. My pump will be located close to the skimmer and return, so my research suggests a 1HP pump should have way more than enough capacity.

However, around these forums I see people with similar sized pools, if not the same exact pool, but they have a 2HP pump. I understand every install is different, but this seems like a really big difference. Am I missing something or do people have pumps that are way oversized?

Also, after some quick online shopping, I've noticed that 1HP pumps don't seem to come in variable-speed; 2-speed seems to be the best I can find. Am I wrong about this or is the VS efficiency gains for a 1HP just not worth the extra cost? Efficiency-wise, would I be better to go to a higher HP to get a VS pump instead of a 2-speed 1HP?

 

[joshhighley]

I don't have anything yet. I'll probably plumb 2" with an oversized sand filter. I can't figure out the need for a 2hp pump on 15000gal, either, but I'm new to this....

 

[scooperhsd]

I have a 1.5 HP on my 19,000 gallon inground pool, and I think THAT is too much. If I had to do it again, I'd probably get a 1HP 2 speed. and I have 1.5 inch plumbing.

 

[mas985]

However, around these forums I see people with similar sized pools, if not the same exact pool, but they have a 2HP pump. I understand every install is different, but this seems like a really big difference. Am I missing something or do people have pumps that are way oversized?

Yes, there are a lot of pools that have over sized pumps. But we aim to change that.

Also, after some quick online shopping, I've noticed that 1HP pumps don't seem to come in variable-speed; 2-speed seems to be the best I can find. Am I wrong about this or is the VS efficiency gains for a 1HP just not worth the extra cost?

In general, it doesn't make sense to build a VS pump smaller than 1.5 HP because they really can't make it any cheaper and if you don't need the flow rate of a 1.5 HP, you can simply reduce the RPM.

Efficiency-wise, would I be better to go to a higher HP to get a VS pump instead of a 2-speed 1HP.

Only if you get a good size rebate from the power company OR you pay really high electrical rates. Then it might make sense to go the VS route.

 

[RH60]

It may depend on the pool. I can tell you I have had a 18" x 4' AG pool for years.
I tried a 1 HP two speed pump since they are recommended. So 1/2 HP low speed for normal use and 1 HP for vacuuming. I had to vacuum my pool way to often. I would run the low speed for 20 hours a day. But it still was a lot cleaner running it in 1 HP for just 8 hours a day.
My guess is the low speed did not keep a strong enough current so the dirt or leaves would float to reach the skimmer. Instead fall to the bottom of the pool.
So for me there is no doubt from my experience that I want as large a pump as possible.

 

[mas985]

So 1/2 HP low speed for normal use and 1 HP for vacuuming.

1/2 speed is not 1/2 HP, it is more like 1/8th HP. So the power is decreased dramatically which is why you save so much energy. But as you found out, sometimes a lower speed does not work so well.