Can’t maintain proper chlorine levels


New member
Jul 19, 2019
Houston, TX

I am a 1st time pool owner and been maintaining it for the past several months. It wasn’t much an issue at the beginning but it’s summertime in Houston and I cannot keep the chlorine levels up. There was an issue with the chlorinator before but that has since been changed out. My pool is less than a year old, gets full sun all day, and a lot of wind being on a corner lot. The builder/pool company hasn’t been able to provide an answer other than raising my CYA which led me to doing some research and finding this forum.

I’ve read some of the suggested links and a few threads over the past few days and decided to join. I went ahead and compeleted the overnight free chlorine test which resulted in .4ppm loss so it seems majority of the loss is during the day. I’m currently running my pump 12 hours per day at 2400 RPMs. After the loss I started the day at 3.2 ppm FC only to test it the next morning resulting in 1.6ppm FC. I’m currently using 3” trichlor (provided by builder) and have been adding bleach as a booster when needed. I saw that everyone recommends bleach instead of tabs. I’m sure i should switch but wanted to use the tabs and shock that was provided before buying other products.

My current levels this evening are:

FC - .6
CC - .6
pH -7.6
TA - 100
CH - 290
CYA - 40

I am currently shocking it to get the FC back up. The water has always been crystal clear and never an issue. The builder suggests our levels are ok at 1.0-1.5 FC since we have an ozone and UV system (wish I found your threads regarding these beforehand). Any suggestions are greatly appreciated. Looking forward to learning and sharing with others.


Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
The UV/Ozone thing may be chewing up some of your FC, so if you can turn it off that may help you.

Keep in mind that each puck you add increases your CYA. The higher your CYA, the higher your FC needs are.
You need to follow that FC/CYA chart Marty posted for you.

Get some more FC in that pool pronto! You're at the level of sending out engraved "Algae Welcome!" invites now.

Maddie :flower:


Gold Supporter
LifeTime Supporter
Jul 16, 2010
Portland, Oregon
Keep in mind if you do discontinue the pucks (best idea EVER!! Your CYA is about perfect right now) that you're switching from the concept of maintaining a certain amount of FC all the time to a new method that means you will dose the pool with chlorine up to your target level each night, and expect to lose around 3-4ppm FC the next day, every day. You don't want to drop below the minimum FC for your CYA level at any time, which is why dosing to the target level before the sun hits the water is important.

Also note that if you have a heavy swimming load, you will lose more than if you just let the sun do it with no swimmers.


Well-known member
Jul 30, 2013
Long Island, NY
If you are losing a lot of FC during the day, you can try dosing a bit above your target FC based on the FC/CYA ensure you never drop below minimum. You can also dose more than once per day, but most people who do this get a SWG or Stenner pump so they don’t have to do it manually. Stop using the pucks, but keep some around in case you go away for a few days.