What Size Pool Pump To Buy?

Vanity

[ExpatCanuck]

I have a 7 year old 40K gallon inground concrete pool and the 2HP pump needs to be replaced. We typically run it 8-10 hours a day and have a DE filter and a spa. I've had someone tell me that if I buy a smaller pump (1HP for example), I can leave it running 24 hours a day and still spend the same in electricity. The advantage being that the water is constantly being moved and filtered and stays cleaner, albeit at a slower rate. Just wanted to get thoughts on this from others here.

[ExpatCanuck]

My apologies in advance if this is posted in the wrong place.

[garykfd]

WHAT VOLTAGE 240?

[driftdiver]

Check the energy use on the pumps. I think the newer pumps are more efficient. Buy a timer and experiment to figure out what is the minimum time. Not all problems are visible though and skin problems can be expected if you don’t get enough circulation.

Also, if you don’t get enough water flow your pool will end up a dark green.

[Abby4116]

From what I've been told, stronger pump is better. It moves the water better and, therefore, doesn't need to run as long to have x number of water changes per day.

The pool guy (who has no financial incentive whatsoever) keeps telling me how great the water movement is since I replaced the old system with a bigger pump.

[Frantzie]

This sounds like a pretty good sized pool. If you buy a 1 hp it will burn up faster. I would run it a few hours a day. I would consider a chlorine generator that generates chlorine from small amounts of salt.

Call some pool places but a 2 hp or 2.5 hp sounds correct.

[avacado]

I think it's the motor you are after and not a pump. The longer the circulation is going it is definitely better for cleaner water and less chance for algae to form. But I would not under power the system only to have weak circulation. Go with the 2HP motor that you have.

[driftdiver]

You can buy a lot of electricity for the chemicals it will take to fix your pool if it gets out of whack.

[Perdogg]

Your kWH output will be directly proportional to HP of the motor given a common voltage. Running a 1 HP motor for 2hrs is the same as running a 2 HP motor for an hour.

[oh8eleven]

I have a 16x36 in-ground (30K gallons) and for 25 years I've always run the filter 24/7. I use a 1 HP Haywood Superpump
I suggest you check with your local swim center for the best advice, then double check prices on-line.
If you wire it for 220V, you'll save on the electric bill.

[Ouderkirk]

The larger the pump motor, the less energy it consumes to do the same amount of work as a lower HP motor. Energy consumption is part of the total load. If the 1HP runs at 90% load, and the 2HP runs at 45% load, the 2HP will consume less energy to do the same amount of work since the current draw at the load will be less.

Volt x Amps = watts.

[Sax]

For keeping it as warm as possible ideally, you only want your pump on during the hottest hours of the day say from 11pm to 3pm. That way all the water circulates and gets heated by the sun.

Running it during cooler hours bleeds off the heat that’s built up, so it’s better to let it sit still.

Of course this all goes out the window if you also have a heater on your pool.

[count-your-change]

Try this site, it seems to have quite a bit of info.:
www.poolplaza.com/pool-pump-sizing-2.shtml -

and yes this should be posted in the Pool Pump Forum.

[Sax]

That's 11AM

[Mariner]

The cost of electricity is DIRECTLY PROPORTIONAL to the amount of work being done.

If you want to move 8 thousand gallons of water/day, it will cost you roughly the same no matter the size of the motor.

[SWAMPSNIPER]

Just don’t let anyone pee in the pool!

[Michael.SF.]

You have been misled.

A 1 HP motor running for 24 hrs. will consume the same amount of energy as a 2 HP running for 12 hrs. Here is the calculation:

2 HP x 12 Hrs x .7457 Kw/ Hp-hr x .12 $/kw = 2.15 $/day

1 Hp x 24 x .7457 x .12 = $2.15

You mention 8-10 hrs per day vs. 24, the only savings will come due to the shorter time of operation, not due to energy consumption.

The real question is how effective are the two methods.

[jessduntno]

“Just don’t let anyone pee in the pool!”

...even if it DOES make it warmer!

[redangus]

We have a 30K, IG, gunnite pool with 1.5 HP motor that runs all Summer (mid-May-early Sept). It’s not killing us on electricity and I think it keeps the heat more uniform and the chemicals better mixed. We also have a salt chlorine generator. Best investment we every made.

[Dennis M.]

Pool pumps are sized to a 8 hour pump cycle. This is because they generally are run during the day such as not to cause noise and problems with neighbors. The rule is the water should be turned over, that is pass through the filter, once in a 24 hour period.

The system is more efficient if the water is pumped slower over a longer period. All else equal, by pumping over a 24 hour period with 1/3 third the flow rate 1/3 the power will be used.

I also have a 40K gallon pool. I use two pumps. One, 3HP is used to run the pool cleaner when I want to. The other is a two speed that I have wired for low speed at 1/3 HP. I run it during the week continually unless I want to clean the pool. It is more costly in hardware but worth it given the cost of electricity in the area I am in.

[Mr. K]

Do people really run their pump that long?

I thought a couple of hours a day was sufficient