Understanding the benefit of a variable pump.

[TheDoc46]

Hi, This is my first post on this forum. So let me start off with a hi !! OK despite being an avid diy'er i've been just taking samples to a local pool store, and every week dumping a gallon of liquid chlorine into the pool, leaving the pump on 8hrs all yr round, and throwing in a chlorine tablet into the chlorine tablet feeder on a weekly basis. The pool has been fine all yr for the most part, but i'm guessing reading this forum, that i've been wasting some money ! But all that is now going to hopefully change, now that i've found this forum !! I'm going to try my best and learn to be more economical from this point onwards !!! At least i've not been paying anyone to do the pool.. Around here its like $80 - $100 a month !!! For a few mins of your time a week. Some people have more money than sense i guess !

A couple of things i want to address is the pump.. It recently died, and as i was in a haste to get the pool moving again, to not get any algae, i just went ahead and replaced the single speed for another single speed. Anyway, i did toy on the idea to get a variable speed but time was of the essence, and i didn't want to just impulse buy without doing the proper research. Which is what i'm doing now !

I have an in-ground pool with no spa, in SW Florida. Poolsize is 10,000 gallons. I'm currently running a single speed 1HP pool pump for 8hrs a day, which according to this Hayward Energy Calculator says i'm turning over my pool about 3.2times a day.


Assuming my rate for FPL is $0.10 / kWh (cos its confusing as heck to figure out what my kWh actually is). My supposed annual electricity cost is $420 per yr.


Thing thats not making sense is my turnover rates... That $420 is apparently going to turn my pool over 3.2 times a day, while running my single speed.


Is 3.2x turnover a day overkill ? Reason i ask is cos if i buy a Variable Speed pool pump, to get my pool to turn over 3.2x a day, it means running it on preset 3, which is 3,000rpm for those 8hrs a day and then that means my savings are only $9 per month. Which basically means it would cost $312 a year instead of $420, that i'm currently paying with the single speed.


Hardly anywhere near the 90% savings advertised. Actually to get to the 90% savings, i would have to change the preset to V1, and that means my pool will only turnover 1.6x a day for those 8hrs. UNLESS i run it for 16hrs, then it goes to 3.2x turnover.. But it'll be at a much slower flow rate. Is the slower rate, ok to filter a pool ? or is there a caveat to running at the much slower rpm? will it successfully skim the pool, like it does now running at over 3000rpm ?


Out of interest what is the 'recommended' turnover for a typical 10,000 gallon residential pool, that doesn't have a spa ? I've read all sorts, is 1.6x a day sufficient, or should i really be shooting for the 3.2x a day turnover ?

Thanks in advance for any advice on this.

 

[Jimrahbe]

Doc,

First.. Welcome to TFP... A Great resource for all your pool questions..

We have found the ideas of "turnovers" is a long-time pool myth. There is no reason to turnover a specific amount of water per day.

The key to good pool maintenance is maintaining a sufficient amount of FC (Chlorine) at all times.

Generally, you run a pump for three reasons:

1. To keep surface debris moving and being pushed into the skimmers. The more debris the more often you need to run the pump.

2. If you have a Salt Water Chlorine Generator (SWCG) you'll need to run it long enough to generate the amount of chlorine needed.

3. To circulate the water to ensure the chlorine is effectively distributed throughout the pool. Two or three hours per day is all that is needed for this to happen in most pools.

There really is no one answer that fits everyone.

Personally, I run my variable speed pump 24/7 at about 1,200 RPM, and doing that costs me less than $20 a month. I'm not suggesting you do that, I'm just suggesting that a VS pump is a real money saver, even running 24/7.

Thanks for posting,

Jim R.

 

[TheDoc46]

Thanks Jim,

I clean my filter every 2-4 weeks. I basically take it out and blast it with a hose. Quite a bit of dirty water rinses out of it, along with small debris, such as dead grass, leaves and a few bugs here and there.. I thought the idea of having the pump running for a good few hrs was to help getting all that into the filter to trap it.

Being that a VS pump is going to push at a lot less pressure, over a longer period of time, does it have enough pressure in the water to get the debris to the filter ?

Basically do the single speeds have any advantages over the VS's. If they cost the same and used the same electricity, which obviously the don't, but if they did, would a VS be better than a single or vice versa ?

Thanks again.

 

[Jimrahbe]

Doc,

Well, that is one good thing about a variable speed pumps. You can program them to do what you want. So in my case, since I have a SWCG, I run slowly most of the time, but a few times a day, I increase the speed to 2,000 RPM, to help the skimmers keep up with the debris on the surface of my pool.

Speaking about filters, I have a large cartridge filter that I only clean twice a year... I only do that because I think it best, but the filter pressure at 1,200 RPM is almost always about 2 or 3 lbs. no matter how dirty it gets...

Not sure what type of filter you have, but I also have two rent house with DE filters and the same VS pumps. I don't have to clean those filter but twice, sometimes three times, a year also. For the DE filters if I let them get too dirty the "no flow" light comes on the SWCG.

Thanks,

Jim R.

 

[gary300]

I run my VSP 6 hours a day at 1500 RPM and it draws 273 Watts. My water is crystal clear and I have never seen one trace of algae. I do keep my FC at the recommended level for my CYA and never let it dip below the minimum. I suspect that I could run my pump fewer than 6 hours a day and still be fine, but my pool is large and it needs time for the skimmers to clear the surface debris. I also have hair nets in my skimmers and use a robot, so my filter only needs to be cleaned once a year.

 

[GaryT58]

I like Jim run my VSP about 24/7 at about 1100 RPM. In winter when chance of freezing at about 800RPM. Can run as low as 650 and still generate chlorine. Huge difference in price from about $100/month to under $10.