FC won't stay in range

[danrock]

I have a 27K salt water pool. I would like to keep my FC around 4, but recently I can't seem to get it above 2.
I am running the filter for 10 hours a day and the SWCG was set to 60% and it was keeping up, but I recently upped it to 70% because it wasn't keeping up.
My test results:
pH: 7.8
FC: 2
TA: 80
CH: 330
CYA: 80
Salt: 3300

Should I up my SWCG to 100% for a few days and see if it can get the FC up to 4 or run the pump longer?

 

[mknauss]

Running at minimum FC (See FC/CYA Levels) is not a great idea. I suspect you have algae -- raise your FC to 10 ppm tonight and do a Overnight Chlorine Loss Test

 

[ajw22]

What model SWG do you have? Put it in your signature.

What is your pump runtime and SWG daily runtime?

 

[Jimrahbe]

Dan,

In theory, your cell in your pool, will increase your FC by .26 ppm per hour if running at 100%..

Most pools use 2 to 4 ppm of FC per day. Using the average of 3 ppm, that means you would have to run your pump just under 12 hours a day with the cell at 100% just to stay even.

Of course the weather and bather load enter into the picture, but the point is that you are just not running your cell long enough, or hard enough, to keep your FC up.

And, as Marty points out, with a CYA of 80 you should be running at 6 or better and never letting your FC drop below 4.

I too would run an OCLT just to make sure you don't have an algae bloom starting.

Thanks,

Jim R.

 

[danrock]

I have a Jandy Pro Series Tru Clear SWCG and my pump runs for 10 hours a day.
Ill do the OCLT and post the results tomorrow.

Thanks

 

[ajw22]

You need to run your pump and SWG longer. Try 100% for 15 hours a day. Find where your FC is riseing and then you can lower % or runtime a bit.

 

[danrock]

OCLT result: 2.2 at night, 1.8 the next morning = 0.4

 

[duraleigh]

The OCLT results look pretty good.

It is common for folks to "demand" that their SWG keep up but yours' simply isn't. That's not uncommon at this time in the swim season.

I would immediately supplement the FC with bleach and up your FC to 6-8 ppm and keep it there by supplementing as necessary.

 

[Jimrahbe]

Dan,

Your SWCG could keep up, if you bring your CYA up and run it at 100% for a longer period of time.

Thanks,

Jim R.

 

[danrock]

Turns out my SWCG was broken. Luckily it was still under warranty.