CH in a Vinyl pool ?

[samt]

I understand that CH is for plaster type pools but is there and reason to have in in vinyl pools?

Do I even need to adjust this?

 

[Black Ice]

If it is too high it can cause scaling/buildup, but I don't think it can be too low. I just ignore it on mine.

 

[Isaac-1]

There is some information that says you may want to keep a minimum of 50 ppm CH even in vinyl pools, but as long as you are above this fairly low minimum you should not worry. I just found myself adding CH to my vinyl pool last week when my CH tested out at 40 (I have very soft water) , so I raised it to about 60 just in case.

Ike

 

[jcowart]

It's not really needed. I would have at least 50ppm in it though. I was told by the pool
store that it would pull it out of the liner. I just laughed and walked out. I would just
use the poolcalculator and cal-hypo once a week to bring it up some without having to
buy calcium increaser. It also helps figuring your csi if you keep up with that number.

 

[samt]

Yea , thanks everyone, I already have some that my neighbor gave me, so I think I will add the min. Based on the pool calc. min.

 

[mickey4paws]

Does anyone know if low CH can be bad for a heat exchanger in a heater? Someone told me that, but I don't know if it's true or not. I have a vinyl pool and CH of 100.

 

[chem geek]

Does anyone know if low CH can be bad for a heat exchanger in a heater? Someone told me that, but I don't know if it's true or not. I have a vinyl pool and CH of 100.

It's not true. Saturating the water with calcium carbonate protects plaster and grout surfaces that contain calcium carbonate from dissolving. The idea of saturating the water to provide a thin layer that protects metal from corrosion is at best controversial (see this link for some expert discussion). Basically, low pH is the worst for metal corrosion, assuming oxidizers are present (dissolved oxygen, chlorine, etc.). The next worst is having higher conductivity as from a higher TDS or salt level. For stainless steel in particular, a high chloride level is more corrosive.

If you have a non-SWG pool so have generally lower salt levels, then a copper heat exchanger should do fine. Remember that tap water used to be chlorinated at 1 ppm FC or so without any CYA so was 10 times higher in active chlorine level than our typical outdoor residential pools, yet copper pipes did not corrode. This was mostly because the pH was usually kept above 7.5 (typically 7.8 to 8.0) and sometimes corrosion inhibitors were added, such as phosphates. My tap water only has 55 ppm CH and a saturation index of -0.7. For SWG pools, copper sometimes is OK, but using cupro-nickel or titanium heat exchangers would be more resistant to the higher conductivity from the higher salt levels.

 

[mickey4paws]

Does anyone know if low CH can be bad for a heat exchanger in a heater? Someone told me that, but I don't know if it's true or not. I have a vinyl pool and CH of 100.

It's not true. Saturating the water with calcium carbonate protects plaster and grout surfaces that contain calcium carbonate from dissolving. The idea of saturating the water to provide a thin layer that protects metal from corrosion is at best controversial (see this link for some expert discussion). Basically, low pH is the worst for metal corrosion, assuming oxidizers are present (dissolved oxygen, chlorine, etc.). The next worst is having higher conductivity as from a higher TDS or salt level. For stainless steel in particular, a high chloride level is more corrosive.

If you have a non-SWG pool so have generally lower salt levels, then a copper heat exchanger should do fine. Remember that tap water used to be chlorinated at 1 ppm FC or so without any CYA so was 10 times higher in active chlorine level than our typical outdoor residential pools, yet copper pipes did not corrode. This was mostly because the pH was usually kept above 7.5 (typically 7.8 to 8.0) and sometimes corrosion inhibitors were added, such as phosphates. My tap water only has 55 ppm CH and a saturation index of -0.7. For SWG pools, copper sometimes is OK, but using cupro-nickel or titanium heat exchangers would be more resistant to the higher conductivity from the higher salt levels.

Thanks very much, Chem Geek, I appreciate your response and the article. Our heater has a copper heat exchanger, I believe. We do have a SWG and try to keep our PH at 7.6 to 7.8 and salt around 3200. Hopefully the heat exchanger will last a while. Kind of wish we'd gotten one with the cupro-nickel.