Switching from Salt Cell to NST feeder

[Steve319]

So, I am not planning on closing my pool as I am in SC and I have a heater. Pool was first put into service this past February at which time PB ran the NST feeder until the temps warmed up enough to start up the salt cell. My question is do I just turn off the salt cell and leave it connected (after cleaning) while running the NST feeder or should I remove it and put a dummy cell in its place while not in use. I have read where some are recommending the dummy cell, but it seems to me it would be better to have water running through the cell even though it's not on. I only plan on heating the pool when needed, it is small so it doesn't take long to get the temp up. Thank you in advance for your input.

 

[JamesW]

What is an NST feeder?

 

[JamesW]

If you mean a trichlor tab feeder, you should make sure that the pump runs continuously or the tabs will cause damage to the system when there is no circulation.

 

[mknauss]

What is an NST feeder?

Cal Hypo Tablet feeder -- Non Stabilized Tablet

 

[JamesW]

Even with calcium hypochlorite tablets, the pump should run continuously to avoid a buildup of concentrated chlorine in the system.

There should be a check valve after the cell and before the feeder intake T to prevent backflow into the cell and heater.

 

[JamesW]

Also, be careful that you never mix different types of chlorine in the feeder as it can explode.

 

[Steve319]

So NST feeder is a system designed by Poolife complete with their own brand of tablets (of course) to use in it, you are correct as it is not designed for chlorine tablets. Not sure if any check valves need to be adjusted, pretty sure they are still the same as when pool builder set them. Only adjustment would be at the bottom of the NST feeder to adjust the amount of chemical getting to the pool.
I appreciate the input but it does not answer my question regarding the salt cell. Thanks

 

[JamesW]

I would use the dummy cell in the interim.

 

[Mdragger88]

as it is not designed for chlorine tablets

They are still chlorine tablets , they are just calcium hypochlorite instead of Trichlor. They will add calcium to your water along with the free chlorine instead of the cya that Trichlor tablets add.
The free chlorine gets consumed but the calcium remains until water is exchanged.

Calcium Hardness - Further Reading

www.troublefreepool.com

 

[JoyfulNoise]

With cal hypo tablets (or granules) you not only get chlorine but calcium as well as lots of carbonate alkalinity because of the chemical manufacturing process. There’s no way to avoid the build up of calcium hardness and alkalinity. In South Carolina that might not be such a bad thing because your water tends to very soft and even mildly acidic. But you will need to track those chemicals very carefully so as to avoid a high saturation index which can lead to scaling. Scaling is very bad for a heater.

Also, I too vote that you should pull the cell and use the winterizing tube. The cell can be cleaned if you see any white scale. Use cleaning vinegar to remove the scale as strong mineral acids can damage the cell plate coating. After cleaning, rinse it with distilled water thoroughly and let it dry out (a hair dryer set on low speed and low heat or no heat will dry the insides out very effectively). Then just store the cell on a garage shelf until you need it next season.

 

[JamesW]

I would probably get rid of the feeder and just use liquid chlorine.

If you do use the feeder, do not use very many tabs.

Many people way overload feeders and this causes huge problems.

 

[JoyfulNoise]

With cal hypo tablets (or granules) you not only get chlorine but calcium as well as lots of carbonate alkalinity because of the chemical manufacturing process. There’s no way to avoid the build up of calcium hardness and alkalinity. In South Carolina that might not be such a bad thing because your water tends to very soft and even mildly acidic. But you will need to track those chemicals very carefully so as to avoid a high saturation index which can lead to scaling. Scaling is very bad for a heater.

Also, I too vote that you should pull the cell and use the winterizing tube. The cell can be cleaned if you see any white scale. Use cleaning vinegar to remove the scale as strong mineral acids can damage the cell plate coating. After cleaning, rinse it with distilled water thoroughly and let it dry out (a hair dryer set on low speed and low heat or no heat will dry the insides out very effectively). Then just store the cell on a garage shelf until you need it next season.

What this will look like in practice is that over winter you need to keep a consistent eye on pH, TA and CH so that PoolMath can properly track CSI. You want to keep your saturation balance at zero or slightly negative. This will require adjusting pH and TA with muriatic acid as-needed to keep the CSI in the proper zone. Otherwise, you risk scaling. And since you have a plaster pool, scaling is an issue.

 

[Steve319]

Thanks for all the input. I ordered the dummy by-pass tube today. Will keep a close eye on chemical numbers and keep posting on Pool Math