Variable speed pump schedule in relation to chlorine methods

[poolbel]

I have a Pentair Variable Speed Pump that basically runs low speed (1700 rpm) from 8 am to 10am. It then runs High Speed (2800 rpm) from 10am to 4pm, then back to low speed until 8PM. I have an inline chlorinator which i understand needs high speed to disperse the chlorine when tablets are inside it, but what happens when i stop using tablets (CYA at sufficient levels) and want to just chlorinate with poured liquid chlorine? Do i need high speed mode anymore or just run low speed for the same amount of time? Run low speed longer? Have to have high speed to get the chlorine run through properly? Im confused about the relationship of high speed to chlorine when no tabs are being used.

Pool is 13k gallons, and im in Texas.

Thanks!

 

[mknauss]

When you switch to liquid chlorine, the highest rpm you will need is that which you need to skim. Run time will be at least 1 hour past the time you add liquid chlorine. Total run time based on skimming needs, with a minimum of 4 hours in summer, less in winter.

 

[poolbel]

Forgive me newness, can you define skimming? I assume its pulling enough water through the skimmers to to circulate the water but how would i determine that number? Is it how many times over the full 13k is cycled?

 

[mknauss]

Skimming is removing the material floating on the pool surface. Leaves, pollen, etc.

Turnover of the water volume is a myth, it has no relation to water quality.

 

[poolbel]

And skimming most likely equals high speed for a certain amount of time?

 

[mknauss]

And skimming most likely equals high speed for a certain amount of time?

Not normally. My pool skims just perfect at the same rpm needed for the SWCG flow switch, 1500 rpm. Others have pools they can run the pump slower and still skim.

 

[poolbel]

But on a non salt water pool, pouring chlorine and running the pump at lower speed would still disperse the poured chlorine efficiently?

 

[mknauss]

Liquid chlorine is hydrophylic, it rapidly disperses in a column of water. So only a small amount of actual mixing is needed.

 

[Pool_Medic]

The whole reason for getting a vs pump is so you can run it at very low speeds (low wattage=low power bill)

it’s rare a vs needs to be run above 2000 rpm and not move enough water.

 

[poolbel]

Excellent information, thank you. My start up and pool school explained it needed to run high speed to get enough flow into the Chlorinator, and the rule of thumb was run it 1 hour for every 10 degrees of temp. It wasnt clearly explained if that was high speed or a combo of low and high. Im not even sure yet the right combo of Chlorinator dial to tab amount to pump speed. But the cya is at 60 and it dont want to use tabs for a bit so that is the origin of my question.

I'm intrigued by the statement that a variable pump would never need to run above 2000 rpm. Wouldnt it need to run higher because of a Chlorinator?

Thanks again!

 

[Pool_Medic]

Remember your chlorinator has settings, you can open it up to get more dissolve. IMO water temp is more important in dissolving those pucks vs flow.

Most pool companies know very little about the finer details of dialing in systems. They install vs speed pumps where I see them running at 2800 rpm 24/7. Drives me crazy lol

 

[cowboycasey]

I run my VS pump at 800 rpm 10 hours a day and 1600 rpm for 2 hours for my SWG right now.. As it gets hotter I will up the SWG to about 6 hours or so... I only run during the day until the water gets over 85 degrees then I run at night..

 

[poolbel]

Well it looks like i can run longer at a lower speed and not worry about the chlorinator for now.

One more point...when you add muriatic acid or anything other than chlorine, i would assume you run the pump faster?

 

[mknauss]

One more point...when you add muriatic acid or anything other than chlorine, i would assume you run the pump faster?

If you like. I don’t. Pour the acid slowly in front of a return. Brush the area if you like.

 

[poolbel]

ack, i feel like i have everything wrong!

To sum it up, low speeds will skim just fine and i only really need a higher speed to get flow through the chlorinator when im using tabs. If im not using tabs, run low speed for longer. Any guesstimates on whats an appropriate low speed? My low is 1700 rpm but maybe its just trial and error?

 

[Pool_Medic]

It is trial and error for flow switches or pressure plates. You just lower speed to see at what speeds they shut off at, adjust up 200-300 to insure they don’t turn off when filter pressure rises.

 

[cowboycasey]

start at 800 rpm and go from there... Mine skims ok at that speed but I have my solar cover on right now so I am just mixing water now so it works fine... for me 1700 is my high speed