Chlorine Generator Requires Pump to Run at 2500+ RPM

[bdan529]

Hi folks, new pool owner here. I have been having some trouble with my chlorine generator. To provide the chlorine generator enough flow for it to start working, I need to run my pump at 2500+ RPM.

Is this normal? It seems high from what I've researched online.

The equipment I have is:
Pump: Pentair Superflo VST - 2.2 THP
ECG: Intellichlor IC20
Heater: Sta-Rite SR200 HD
Filter: Hayward S-220T

For reference my loop is as follows: Pump Discharge -> Filter -> Heater -> Check Valve - Chlorine Generator -> Pool. The pump, filter, heater, valve and generator are all within a foot or so of each other so I doubt there is much head loss from this perspective.

I've emptied the skimmer basket, backwashed the filter, acid washed the chlorine generator cell and replaced the flow sensor.

I noticed that the check valve was installed right at the inlet of the chlorine generator, could it be causing turbulent flow inside the cell?

Any advice would be much appreciated, picture below for reference:

 

[ajw22]

Welcome to TFP.

I noticed that the check valve was installed right at the inlet of the chlorine generator, could it be causing turbulent flow inside the cell?

Yup, that can do it.

The Intellichor Installation Manual says - For best flow sensing, provide at least 12"-18" of straight pipe in front of the cell inlet.

That check valve is not needed with a SWG. It is leftover from when tablet chlorinators were used.

If I were you I would remove the check valve cover, remove the spring and flapper, and replace the cover. See what difference it makes.

Your SWG should get flow on at around 1800 - 2000 RPM.

 

[JamesW]

Filter pressure at different speeds?

 

[JamesW]

SuperFlo® VST Pool Pump

Pentair SuperFlo VST Variable Speed Pool Pump for inground pools is for pools requiring up to a 1.5 HP pump. This pump is a TradeGrade product.

www.pentair.com

https://www.pentair.com/content/dam/extranet/nam/pentair-pool/residential/pumps/archive/superflo-vs/manuals/supervs-install-english.pdf

 

[JamesW]

You should probably be getting a good flow light at about 1,500 RPM.

 

[ajw22]

You should probably be getting a good flow light at about 1,500 RPM.

Without the heater I would agree.

My experience is the MasterTemp/StaRite heater adds 300-400 RPM.

An automated heater bypass, like I use, can get it down to around 1500 RPM with the OP setup.

 

[JamesW]

My experience is the MasterTemp/StaRite heater adds 300-400 RPM.

Yes, heaters have horrible hydraulic efficiency.

They really need to fix that.

 

[Jimrahbe]

Dan,

How big is your pool in gallons???

I suspect that having a smaller VS pump vs. a larger VS pump probable has an impact on the rpm required to turn on the cell...

People with no heaters, and large pumps, can run at the lower speeds that you often see posted here at TFP..

Thanks,

Jim R.

 

[Bperry]

Dan,

How big is your pool in gallons???

I suspect that having a smaller VS pump vs. a larger VS pump probable has an impact on the rpm required to turn on the cell...

People with no heaters, and large pumps, can run at the lower speeds that you often see posted here at TFP..

Thanks,

Jim R.

I’m able to get mine down to 600rpm and the flow switch is happy. No heater though.

 

[bdan529]

Welcome to TFP.



Yup, that can do it.

The Intellichor Installation Manual says - For best flow sensing, provide at least 12"-18" of straight pipe in front of the cell inlet.

That check valve is not needed with a SWG. It is leftover from when tablet chlorinators were used.

If I were you I would remove the check valve cover, remove the spring and flapper, and replace the cover. See what difference it makes.

Your SWG should get flow on at around 1800 - 2000 RPM.

I was thinking about giving this a try as well. Why does the SWG not require a check valve to prevent water from flowing back into the heater? I understand the cell won’t generate chlorine at low/no flow conditions, but the water sitting in the cell when pump stops could flow back into the heater? Is it just not enough chlorine present to make a big impact in terms of corrosion?

 

[bdan529]

Filter pressure at different speeds?

Filter pressure varies maybe 10 PSI at the various speeds, at low flows it’s around 5 PSI and going up to 15 when priming or running the pump at high speeds (2500+ RPM)

 

[bdan529]

Dan,

How big is your pool in gallons???

I suspect that having a smaller VS pump vs. a larger VS pump probable has an impact on the rpm required to turn on the cell...

People with no heaters, and large pumps, can run at the lower speeds that you often see posted here at TFP..

Thanks,

Jim R.

Pool is about 15,000 gallons. It’s my first time owning a pool, not sure if that qualifies as a large volume given the size of the pump.

 

[ajw22]

I was thinking about giving this a try as well. Why does the SWG not require a check valve to prevent water from flowing back into the heater? I understand the cell won’t generate chlorine at low/no flow conditions, but the water sitting in the cell when pump stops could flow back into the heater? Is it just not enough chlorine present to make a big impact in terms of corrosion?

Tablets contain acid. When the pump turns off, the tablets continue to dissolve, creating acidic water at the chlorinator that will backflow into the heater and damage it. The check valve tries to prevent that.

A SWG contains no acid. The generated chlorine level is low and will not damage the heater. You run higher chlorinated water through the heater during the SLAM Process.

 

[bdan529]

So I removed the the flap from the check valve and it made little no difference in terms of RPM required to get the mimimim flow for the SCG.

 

[ajw22]

What is your filter pressure at different speeds?

Unfortunately, you do not have a heater bypass to determine if your heater is causing the problems.

Post pictures of your entire equipment pad showing all the valves.

 

[JamesW]

Filter pressure varies maybe 10 PSI at the various speeds, at low flows it’s around 5 PSI and going up to 15 when priming or running the pump at high speeds (2500+ RPM)

Post actual pressure at each speed.

 

[Jimrahbe]

Pool is about 15,000 gallons.

Dan,

We always recommend a cell that is at least 2 x the volume of the pool... This means we consider your cell to be on the small size for your pool.. The good news is that you are not located in Texas, so you probably won't have have a big issue with it being too small.. You will have to run longer and harder to generate the chlorine that your pool will need each day.

Thanks,

Jim R.

 

[bdan529]

What is your filter pressure at different speeds?

Unfortunately, you do not have a heater bypass to determine if your heater is causing the problems.

Post pictures of your entire equipment pad showing all the valves.

Sure thing here are the PSI readings (gauge on top of the filter) at 250 RPM increments

1000 RPM - 0 PSI
1250 RPM - 1 PSI
1500 RPM - 3 PSI
1750 RPM - 5 PSI
2000 RPM - 8 PSI
2250 RPM - 10 PSI
2500 RPM - 12 PSI
2750 RPM - 15 PSI
3000 RPM - 17 PSI
3250 RPM - 19 PSI
3450 RPM - 22 PSI

Pictures of the entire set up below:

 

[bdan529]

Post actual pressure at each speed.

Sure thing
1000 RPM - 0 PSI
1250 RPM - 1 PSI
1500 RPM - 3 PSI
1750 RPM - 5 PSI
2000 RPM - 8 PSI
2250 RPM - 10 PSI
2500 RPM - 12 PSI
2750 RPM - 15 PSI
3000 RPM - 17 PSI
3250 RPM - 19 PSI
3450 RPM - 22 PSI

I've also posted pictures of the entire set up in the thread as well.

 

[ajw22]

All that flex PVC is not good.

Looks like this hose has collapsed.