Low chlorine level in a salt water pool...

Greetings, I also posted this in another thread, but figured it belonged here.

I have a new salt water pool, approx 27,500 gallons, in-ground, with Goldline/Aqualogic equipment. The problem I am having is my Free Chlorine level has been practically zero. PH and all other levels are fairly normal, though I've had to drive the PH down some.

After intial shocking using the chlorinator, I ran the CYA at about 30ppm. I used bleach a couple times to get the FC level up, but figured I needed to start relying on the chlorinator.

After hearing that salt water pools require higher CYA, a couple days back I added stabilizer (using tied up socks in the skimmer to desolve the stuff). Today the CYA read 70 ppm (where I absolutely cannot see the black dot.) But my FC level is still pretty much zero. How can I get the FC back up?

Do I need to wait a couple more days for the CYA level to take effect, or is there something else I need to do. Chlorinator level of the spa is 10% and pool is at 50%. I'm thinking I may need to shock again. Weather here has been cold, with some rain.

Any suggestions or advice will be appreciated.


Mike

Depending on how cold it is, your system may be shutting down in a protection mode. Your manual should indicate the temperature at which the protection mode kicks in.

If the system is operational, you may need to increase the output level of your system to see what happens.
For example, the 50% setting means that if the cell is rated for a 40,000 gallon pool, unless you're running your pump 24 hrs/day and the operating conditions are ideal, 50% = 20,000 gallons worth of treatment.

Check and make sure you don't have any combined chlorine, which can cause a higher chlorine demand (consuming the chlorine produced until it is overcome). If there are combined chlorines, you should shock the pool manually, rather than boosting the salt system.

Hope this helps,

Mike,

How long are you running your pump? For the AquaLogic and your size pool, to add about 1 ppm per day of chlorine, you will need to run your pump about 8 hours at 50% (4 hours @ 100%). Also, what is your salt level?

Mark,

Thanks for replying... We run the filter pump from about 9:00am to 5:00pm, but about half of it is run at low speed. Also, salt level is reading 3100ppm. Is it safe to boost the chlorinator output higher than the current level of 50% for the pool and 10% for the spa?

My combined chlorine is also negligible. PH level is at about 7.8, alkalinity about 110ppm, and calcium hardness is about 230ppm. I'm using the best test kit Leslie's has, but keep hearing how people 'order' theirs through the mail. Is this adequate?

We were in the spa last night, and my wife thought she smelled a 'funny' odor in the water. I was really wondering if this is due to the low chlorine level. Do I need to break down and throw some bleach in there, or maybe shock it using the chlorinator?

Hey, thanks for your help...

Mike

From lifespan point of view, it does not matter if you run a SWG for 8 hours at 50% or 4 hours at 100% it is still 4 hours of SWG run time. So yes, you can increase the % setting if you need to but it will impact the life of the cell. However, with an 8 hour run time, you should be getting over 1 ppm residual so it could be the chlorine is killing some algae in the water. A shock might help this.

Ph is a little high. I would target 7.2-7.4 which will allow the chlorine to work better. Alk is a bit high but when you lower PH, that will come down as well.

If you are smelling something that is usually CC so a shock may be in order. However, I would do that with liquid chlorine to save on the life of the cell.