CH in vinyl pool - why the minimum target?

[blumsden]

Just out of curiosity, if CH is not a concern in a vinyl pool, and some people have 0 or very low CH with no problem, why recommend the minimum of 50 at all? Reference http://www.troublefreepool.com/pool-school/recommended_levels. My level is testing at 40, so I plan to leave it, but I was just curious about that minimum value.


Thanks!

 

[JasonLion]

Welcome to TFP!

When we were making up the standard levels we discovered that we don't have enough examples of vinyl pools with CH below 50 to be completely sure what happens. The few vinyl pools we know of with CH that low never had any problems, but there weren't enough of them for us to be completely sure. Thus, we picked 50, because we can be completely sure of 50.

 

[blumsden]

Reasonable! Thanks

 

[JohnN]

My CH is currently at 20. I will let you know if I notice any problems this year. I was running about 30 last year, and I assume since the pool was installed. The pool is about 7 years old, and I have not noticed any problems.

 

[Bama Rambler]

I've had zero CH for the last 5 years and have had no problems. The vinyl is just as supple as the day it was installed. Since I've followed the TFP method almost since the beginning I don't know if that is the reason or the zero CH is.

 

[bk406]

I havent added any calcium in my vinyl pool for 3 years. It's basically zero. Never had an issue

 

[mmcgovern]

This forum is awesome. I was going to post and ask about this very thing but here's my answer and I didn't even have to ask the question!

 

[jblizzle]

This forum is awesome. I was going to post and ask about this very thing but here's my answer and I didn't even have to ask the question!

Thanks for using the search function ... amazing what you can find

 

[bumpy1]

The devil is in the details. If you have a vinyl liner pool with fiberglass steps you may need to maintain a CH of 150, otherwise your steps can become compromised and/or end up with blistering.

See this thread for details and pics: did-low-calcium-cause-my-fiberglass-steps-to-blister-t65720.html

 

[mmcgovern]

Good point. I suppose I should error on the side of caution then and add some.

 

[Isaac-1]

Much the same here, liner is about 8 years old, have not added any CH in a few years, fill water has a CH of 30 ppm , pool currently just under 40 ppm CH. Note some liner manufacturers specify certain CH for warranty coverage, if this is just a random number or not I don't know.

Ike