Stabilizer is very UNstabilizing...

[mctol]

I added an "automatic" chlorinator two years ago and shortly after started having problems with yellow algae. I recently bought the TF-100 test kit and with help of this site am finally starting to understand that even though I was shocking the pool with what I thought was a high enough amount of liquid chlorine, with a stabilizer reading of 50 I was not getting my FC levels up high enough to "finish off" the algae. So let's talk a bit about stabilizer.

Does stabilizer EVER break down or can you reduce it any way other than removing some water?

What is the "normal" reading to have with stabilizer for a fiberglass/vinyl pool that gets a lot of sun but frequently uses a solar cover?

Should I just remove the chlorinator from the system?

I used to think that when we went on vacation, I could just turn the chlorinator up a bit and we would be fine. BOTH TIMES that I tried this resulted in an algae outbreak (now I think I am starting to understand why). I thought I could just shock the pool with the chlorinator turned on 10.

Thank you for this site and for the many people that make this a productive and helpful forum!

 

[MikeInTN]

I added an "automatic" chlorinator two years ago and shortly after started having problems with yellow algae. I recently bought the TF-100 test kit and with help of this site am finally starting to understand that even though I was shocking the pool with what I thought was a high enough amount of liquid chlorine, with a stabilizer reading of 50 I was not getting my FC levels up high enough to "finish off" the algae. So let's talk a bit about stabilizer.

Does stabilizer EVER break down or can you reduce it any way other than removing some water?

What is the "normal" reading to have with stabilizer for a fiberglass/vinyl pool that gets a lot of sun but frequently uses a solar cover?

Should I just remove the chlorinator from the system?

I used to think that when we went on vacation, I could just turn the chlorinator up a bit and we would be fine. BOTH TIMES that I tried this resulted in an algae outbreak (now I think I am starting to understand why). I thought I could just shock the pool with the chlorinator turned on 10.

Thank you for this site and for the many people that make this a productive and helpful forum!

The only way I know of that CYA gets removed from a pool other than by removing water is sometimes by soil bacteria that gets in over winter and eats the CYA. Happened to me last year - opened the pool this year, CYA was 0. Other than that, you'll need to replace water to lower it.

For a non-SWG chlorinated pool, your CYA should be between 30 - 60, and as you've found, the higher the number, the higher your FC has to be to maintain sanitation. Here's a sticky on the ABC's of pool chemistry.

Personally, I wouldn't remove the chlorinator. Unless you have someone who can come by while you're on vacation and add chlorine to the pool, keep it so you can use a puck or two while on vacation to maintain chlorine in the pool. If you have someone to add chlorine to your pool (or are going to a SWCG), then it becomes expendable. In fact, that's where I added my SWCG in my plumbing - where the chlorinator used to be.

Welcome to TFP! :-D

 

[JasonLion]

It is indeed important to understand the relationship between the stabilizer (CYA) level and how much FC you need to have. This table shows that relationship clearly.

As long as you are aware of this relationship, it is possible to use trichlor tablets sparingly. A puck feeder is particularly handy when you are going on vacation and don't have a SWG or Liquidator. But when you do that you need to be aware that it will raise your CYA level and you will need to raise FC to compensate for that.

The most common recommendation for CYA level is between 30 and 50. If you have a SWG or extreme amounts of direct sunlight on the pool, you can use CYA levels between 60 and 80. Higher CYA levels use less chlorine day to day, but higher CYA levels also make it very difficult to get rid of algae once you have it.