Can't keep FC up - Salt water pool in TX

Aquitaine

Active member
Jun 23, 2021
25
Austin, TX
Bought my house with an in-ground @12,000 gal pool in June of 2021. TFP saved my bacon. Bought a taylor test kit and I put in a salt cell (circupool RJ30+) and got it stable pretty quickly. It's been a marathon replacing old parts but everything has been going smoothly. In Central TX (Austin) so we don't really close our pool (there's no cover) but this is not new.

In early May, I noticed that the FC level was dropping from the usual 4-6ppm. CYA was low (about 30) so I got it up to 75 and added some shock to get back up to 6. Cranked the salt cell to 100%. FC had crashed down to 1 by the following week.

The salt cell was rated for 15k hours and I had exceeded that, so I de-scaled it, gave it another couple days with no change, then ordered a replacement (just the cell, the console part was working fine). Put in the replacement, no change.

I read up on reddit and ChatGPT and both say a) check the phosphate level (which I'd never done before) and b) shock the heck out of it, that there is sufficient FC demand that the salt cell can't keep up. I dumped in the last of my solid shock and added 2 1 lb bags of shock powder (and have ordered more). It went back up to 6ppm FC yesterday. Bought a phosphate test and it showed 0 (which makes sense, there's not really a source of phosphates anywhere near my pool)

1 day later (today), FC is 3ppm.

Did I just not shock enough? It seems unlikely that a brand new salt cell is busted but this has never happened before and this is the 4th year I've prepped the pool for the Summer. TY TFP!
 
I forgot to mention, water is (and has always been) crystal clear the whole time. But the numbers don't lie, I guess? SLAM it is!
Note that depending on what “shock powder” you added, that can cause cloudiness problems and will raise your calcium levels and/or CYA levels. That’s why we only recommend liquid shock (aka liquid chlorine).

Don’t get me started on Reddit and ChatGPT…
 
But the numbers don't lie, I guess? SLAM it is!
Algae is microscopic. If you can see it, the exponential growth is a runaway freight train, and why its such a beast to control a swamp.

Frequent. Reliable. Testing.

tosses red flags while you still have the upper hand in the imminent battle.
 
ChatGPT actually got it right here (it said SLAM right away!). I've just never had to SLAM a clear pool before. Liquid chlorine also a little tougher to come by but I found a bunch at Walmart. The shock powder was left over from the previous owner (in 2021!) -- that's how rarely I've had to shock!
 
ChatGPT actually got it right here (it said SLAM right away!). I've just never had to SLAM a clear pool before. Liquid chlorine also a little tougher to come by but I found a bunch at Walmart. The shock powder was left over from the previous owner (in 2021!) -- that's how rarely I've had to shock!
Checking for phosphates isn’t something that needed and there’s a huge difference between the SLAM process and “shock the heck out of it”. 😉

For future reference, You should never have to “shock” the pool if it’s being maintained adequately.