CYA and trichlor....chemistry questions


New member
Aug 31, 2019
Rockwall, TX
We just had our first pool built and it was finished in the spring. We have never owned a pool before so I did a LOT of research. We ended up going with the inline trichlor feeder because going the SWG route was highly discouraged, not by the builder...but by people in our neighborhood. We are required to have a 4 foot iron fence around the yard (we are on a golf course) and we were told from some people's experience that a SWG will rust the fence very quickly. I was shown some examples, so I heeded their advice.

Anyway, I am somewhat stuck with the trichlor feeder. I do my own pool cleaning, but we are away from the house for a day or two on a regular basis so I can't be there to add chlorine every day. My question is two-fold....
1. Does the CYA in the pool (lets say a level of 40) protect the chlorine in perpetuity without adding more throughout the season (assuming no splash-out or dilution for the purpose of this question)?
2. Is there ANY 3 inch chlorine product I can add to my feeder that DOESN'T contain CYA? Calcium Hypo has it's own set of problems and I don't think they are made in 3" tablets anyway.

I wish my "extensive" research included this site but, at the time, I was much more concerned about the construction aspect. I kind of thought the chemical situation was more simple...OOPS!


Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
Welcome to the forum!
Sadly, you were led down the path of many Texas new pool owners in not installing a SaltWater Chlorine Generator.
The CYA builds up from continuous trichlor use. A little will degrade during swim season. If you keep the CYA at 40-50 ppm by using liquid chlorine, you will have room in your CYA level to use trichlor when you will be away from the pool for a few days. But do not use trichlor exclusively.
There are only two readily available chlorine products in puck form. Trichlor and Cal hypo. I suspect your fill water has enough calcium in it, so regular use of cal hypo is not recommended.

Your best move is to install a SWCG. Or a Stenner type liquid chlorine dispenser.
I suggest you read ABC's of Pool Water Chemistry.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

So, you checked all the fences in your neighborhood and saw for yourself that only fences where the owner had a saltwater pool had rusted, but all the rest were OK??

Or.. you assumed that nothing rusts unless subjected to saltwater...?

I just can't picture this happening. I have three saltwater pools, and granted I do not have a cast iron fence, but I have plenty of other metal stuff around my pool and nothing has ever rusted..

Not saying the fences had not rusted, but doubt that the saltwater had anything to do with it.. In fact, most pool become saltwater pool over time as the salt from chemicals continues to build over time.


Jim R.


New member
Aug 31, 2019
Rockwall, TX
Thanks guys!
I really wish there were a way, or someone who made them, to have a puck of chorine with out all the "extras". I'll look into the liquid dispenser. That was never brought up as an option.
Jim, I saw not only the rusting fences, but rust on metal parts that were close to the pool (fixtures, chairs, grills, etc.). It only seems to affect things that are directly adjacent to the pool. People that had the pool farther from their patio or fence didn't have as much of a problem, but unfortunately, we are on the end of a cul-de-sac and have the "pie" shaped lot that isn't deep enough to be far from either.


TFP Expert
LifeTime Supporter
In The Industry
Jun 12, 2009
NW Ohio
I would love to see some salt levels on the pools without damage and pools with damage. I bet some people would be quite surprised.

The reason salt pools get blamed is because quite a few people buy them thinking they are essentially maintenance-free. So their chemistry gets way out of whack, especially the pH, and that is what causes these problems. I have seen awful damage caused by low pH but never any damage caused by salt in a pool. I cannot stress enough how salt in pool water is just one variable to the potential for it to cause problems and one of the lesser variables at that. I am not calling your neighbors or builder liars, only that they are not well versed in water chemistry. Most builders are experts at construction, I give them all respect for that, but their understanding of water chemistry is almost universally lacking. Ask them if tablets add any salt to the water. The answer, BTW, is yes, because chlorine breaks down to chloride so all forms of chlorine add salt.

Saying you want someone to invent pure solid chlorine tablets is like saying you want pure solid water that isn't cold. Sure, that would make things easier if it wasn't impossible at normal air pressure. Sorry, but ye canno change the laws of chemistry, captain (said in my worst Scottish accent).

Welcome to TFP!