What is the minimum VS pump speed for a salt system?

PSC Ep. 67: Minimum VSP Speed for salt system to work?

In today’s episode of Poolside Chat, Rob and Matt tackle another common swimming pool question: 
  • What is the minimum VS pump speed for a salt system?

“I’m programming my variable speed pump, and have a question. What speed should I set the pump on to make sure my salt system continues to work?”

Goldline / AquaLogic Flow Switch 15' Cable (No Tee) (GLX-FLO-RP)
AquaRite Flow Switch

The concern would be that if you run the pump at too low of a speed, it’s not going to trigger the flow switch; which tells the salt system to run or shut down. Basically, the flow switch is what goes after the salt cell. There’s a switch in there with a two-prong piece, basically with two points of contact. If there’s enough flow those two points of contact are going to touch telling the system to run. If there’s not enough flow, those two points aren’t going to touch and scan, so it’s also is not going to run.

The answer to the original question, every pool is different. There isn’t a set speed. Most of the salt systems are going to require 10 to 25 gallons per minute. Check your owner’s manual to see what your system’s going to require. What you want to do is start the pump on a low speed and kick the speeds up until the salt system says, “It’s okay. It has enough flow.”

To compensate for when your filter gets dirty, once you find that low benchmark, you want to actually set the normal filtering level like a couple of notches above, just so when your filter gets dirty and the flow gets restricted, your salt chlorinator out of runtimes or flow sensor isn’t affected. Set it a couple notches above and you should be good for those dirty days.

2 thoughts on “PSC Ep. 67: Minimum VSP Speed for salt system to work?

  1. THANKS Matthew for the infor…..I NEED YOUR HELP!!! i HAVE reversed the water flow, that is, the intake valves WERE the out go and NOW they serve as “ports” through which the water is “sucked” into the pump and then to the filter….. there are three such intake “ports” that get the water to the pump/filter….this enables me to design several water features on the sides of the shell that trip into the pool and serve as air filtering as well as providing interesting water features…..a regular zacuzzi just isn’t all that aesthetically pleasing to me….sooooooooo…..the shell is standard, i.e. 2 level steps into the water, one seat and two /stretch outs….about 4 feet deep…..I calculate about 700 tp 1500 gals with a half hourse pump…….TRYING TO FIGURE about how much time the pump needs to be on…..CAN YOU HELP THIS RETIRED OL FART LIVING ON THE BEACH IN THAILAND?????PLEASE, PLEASE, PLEASE!!!!
    Regards, Keith /

    1. I believe we mention this in the video, but it is going to be different for every system. You have to play with the runtimes and RPMs a bit, to find out where the sweet spot for your setup is. Maybe I am getting turnaround a little by your description, but I couldn’t tell you off hand how long you are going to run it.

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