Why is recommended CYA for salt water pools so high?

[Liz315]

So I completely trust the TFP method. I’ve seen following it and have gotten others to as well and will continue to.

This question is just so I understand why I’m doing what I’m doing. Why is the CYA for salt salt pool recommend at 70 but then if you ever had to SLAM your pool (which I never want to do and don’t believe I will) it tells u a slam at 70 is not recommended. I’m sure because it’s not practical at such a high amount.
Right now my swg pool is 60 (which isn’t recommended)and I’m trying to figure out if I should increase it to the recommended 70. Currently I aim for my FC to be a 7, which will probably stay the same with a CYA of 70.

Also, I’ve read Salt water pools require less chlorine but using the chart it shows a regular pool has the lowest recommended CYA at a 30 only requiring a FC of 3-6. based on the salt pool chart 7 seems like the lowest recommended FC to avoid algae. I know there’s a reason I’m just trying to understand why.

I’ve watched the videos but I’d love more clarification.

 

[mas985]

The higher the CYA, the higher the FC level you need BUT the lower the FC you need to add each day. So in the long run, the cell lasts longer with higher CYA.

CYA vs UV Chlorine Loss Test Update

Many years ago, I did a test of chlorine loss vs CYA level and published the results here: https://www.troublefreepool.com/threads/cya-testing-update.2984/ There were a few issues with the test that I wanted to resolve with some additional testing but never got around to doing it...until now...

www.troublefreepool.com

 

[Liz315]

So that makes sense so My FC Loss is less each day than if I had lower CYA.

what about the 60 vs 70 and 70 being recommended for FC but not for SLAM

 

[an1vrsy]

By always maintaining your FC to CYA ratio, you will never need to SLAM. Let's say, you having a pool party, well bump up your FC with either the SWG percentage or add liquid chlorine ahead of the pool party. There are members here who have never SLAM'd

 

[Texas Splash]

Also remember that manual pools add "liquid" chlorine all at once (glug-glug-glug), whereas the cell is producing chlorine gas (hence the bubbles) in smaller bursts or cycles throughout the day. So the smaller bursts of FC are sustained better with the elevated CYA. As for which is better, 60, 70, or 80, it all depends on the stress being applied to your chlorine. Here in south Texas, the heat and UV intensity are significant, and we all know what it's like in the southwest, so these locations require more FC protection. Some other areas of the country might get by with a slightly less CYA if the sun isn't as intense or if the water gets a fair amount of shade. It's something you get the hang of over time as you adjust CYA, output %, and pump run times throughout the seasons.

 

[manofice3484]

By always maintaining your FC to CYA ratio, you will never need to SLAM. Let's say, you having a pool party, well bump up your FC with either the SWG percentage or add liquid chlorine ahead of the pool party. There are members here who have never SLAM'd

This exactly. Before I knew about the CYA to FC, I had a pool party and the next day I had to shock it because FC got low and CC was elevated a little. Just had a pool party yesterday after maintaining the proper CYA to FC ratio and bumping the SWG up a little bit the day before, my levels are perfect even after the party.

 

[Mdragger88]

A SLAM Process at 70 or 80ppm cya is not impossible, just somewhat impractical for most as it requires alot of bleach & regeants.
We generally direct most people to slam @ the lower cya then raise it up to swg recommendations after passing end of slam criteria & maintain proper fc amounts so they hopefully never have to slam again.

 

[Oly]

Right now my swg pool is 60 (which isn’t recommended)and I’m trying to figure out if I should increase it to the recommended 70.

This is the great thing about owning a good test kit, you can determine your daily FC loss at your current CYA level and decide if that works for you. Or you can bump up your CYA in 5ppm increments and determine the reduction of daily FC loss to dial in your unique system. Guidelines vs empirical evidence.

 

[PullJunkie]

..... There are members here who have never SLAM'd.....

 

[Liz315]

That’s my goal. Was just curious how it all worked just in case.