# Thread: Not sure how to interpret these numbers

1. ## Not sure how to interpret these numbers

Under the Suggested FC Levels it has the values, what do they mean ??

SWG: 2 Normal 4 to 8 Shock: 20 Mustard Algae Shock: 29

I get my Targets from TFP.

My FC is 13 and my Target shows as 8.........but pool math doesn't say to do anything. I should just leave it alone? My SWG is on Max and running 7 hrs a day. Unless otherwise advised, I will turn down my SWG % and lessen my run time by an hour or 2?
Sound correct ?
CC is .5
The rest I understand and is easily manageable.
I was gone to America for 5 weeks and my maid added one bag of salt while I was gone and ran the robot every day but I surely didn't want her messing with chemicals.

My water is still crystal clear, s always.

Bruce

2. ## Re: Not sure how to interpret these numbers

Values are concentrations expressed in ppm (parts per million; milliliters per cubic meter).

Higher FC concentrations are required for higher CYA concentrations.

Once you know your CYA ppm, the chart linked above shows three FC ppm: minimum to avoid starting biological growth(s) (e.g., algae), target to aim for when you add liquid chlorine if your SWG isn't maintaining minimum (allowing you to adjust your SWG output to achieve minimum), and shock value if you end up with biological growth and have to SLAM.

So before using PoolMath, read the linked chart to identify your targets (enter into "Target" column in PoolMath). Enter your test results in the "Now" column, and PoolMath will tell you what to add to go from your now/test value to your target value.

In your case your test value for FC (13) is greater than your target value (8), so PoolMath finds nothing to do.

The most critical number in PoolMath is "Size _____ gallons." Everything in PoolMath is based on your pool's water volume; be as accurate as possible.

IMO this part of PoolMath is outdated, and should be ignored. Use the linked CYA/FC chart instead:
Capture.JPG

Confirm your CYA concentration; I'm guessing you can turn down your SWG significantly.

3. ## Re: Not sure how to interpret these numbers

If you are having to run your SWG at 100% 24x7 it is likely either way undersized, or you have something consuming your FC, you might want to do an overnight chlorine loss test to confirm an issue. Pool School - Perform the Overnight FC Loss Test (OCLT)

4. ## Re: Not sure how to interpret these numbers

The pool math is basically assuming you are using liquid chlorine. So to reduce from 13 to 8, you don't add any more and wait for it to reduce. Since you have a SWG, you would want to turn down the %age and/or run time.

5. ## Re: Not sure how to interpret these numbers

What model of EMAUX SWG do you have?