Chemical Parameters for Salt Water Pools

Norman Eaglestone

New member
Jan 20, 2019
2
South Carolina
I keep getting conflicting parameters for a salt pool using a SWG. I have a small 4590 Gallon pool with a Pentair IC40 SWG. All things considered, the pool water looks great, no smells, no algae etc. I am taking over maintenance, from the pool company and not completely sure about what the target parameters for a salt pool should be.

The obvious action is to call Pentair and speak to an expert, with the primary focus being on CA and FCL.

Support strongly advised me on two actions:
1. FCL & CA: Keep the FCL between 1-3ppm and the CA between 30-50ppm
2. Become a member of TFP and go carefully over that website and their book. Right up front in that book, the recommendation for FCL is 5 ppm and CA between 70-80.

So therein sits the problem, with these conflicting numbers

The argument for low CA levels seems to be based on the idea that the SWG is generating CL constantly. Possibly an argument against low CA levels is that the SWG never runs 24 hours a day but more like 8 to 12 hours. Perhaps the fine line here is that higher CA levels are indeed required to help maintain the CL levels when the SWG shuts down. In my case I run 8 hours a day and stop at 1500 when the power rates increase ten fold. I believe I loose about 6ppm in CL daily due to the sun, so this suggested to me that I may be better off pushing the CA up higher into the 70-80ppm levels suggested on this website and others, but cautious about the manufacturers guidance.

There is also a useful formula that states that FCL should be = to 7.5% of CA, so when using the higher CA level of 70-80 puts the FCL around 5-6 ppm.

For more completeness

Pentair support suggests:
FC 2-4
pH 7.2-7.4
ALK 80-120
CA 30-50
Salt 3600

TFP WEBSITE AND BOOK SUGGESTS FOR A PLASTER SALT WATER POOL
FC 3-5
pH 7.2-7.8
ALK 69-80
CA 70-80
Salt 3609

So there is some discrepancy between the FCL, ALK, CA & pH levels for SWG, salt based pools. What should these parameters be for a salt water pool.

Thanks

Norm
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
14,005
Bedford, TX
Norm,

Our parameters do not match pool store, or manufacturer's, parameters because we factor in the CYA level..

There is no discrepancy here, our parameters just work better...

Most of our members are here because they followed the pool store's parameters and ended up getting algae two or three times a year.

Our parameters are safe and will not cause any damage to your equipment.

I have three pools with Pentair IC40 SWCG's that run an FC of about 7 or 8 and a CYA of about 70.. They have been running for a "total" of 19 combined years and I have never had algae and the equipment has had zero failures, if you don't count a lightning strike on one of them. :)

It is your pool and you can do what you want, but I will never use anything but the TFP guidelines..

Thanks,

Jim R.
 

Norman Eaglestone

New member
Jan 20, 2019
2
South Carolina
Jim,

thanks for the feedback. I had noticed that the pool app includes the CA level and I believed that was important.

Your tables indicate a CL level of 5

I have read several places that indicate the CL should be based on 7.5% of the CA level which at the higher rates puts CL at 6ppm or higher. Currently I have increased my CA to 80, which by the formula suggests CL at 6+ ppm.

Is there a level for CL that will begin to damage poor or equipment. I think your app indicated going as high as 9 or 11 for CL which seems pretty high

Thanks again

Norm