# Thread: Pool Math and FC?

1. ## Pool Math and FC?

Pool Math tells me that my FC should be a minimum of 4 with a Daily Goal between 9 and 11 yet the suggest level listed elsewhere on TFP say much lower.. like 3-5. Why is this? What should my FC level actually be?

2. ## Re: Pool Math and FC?

Your recommended FC depends on what your CYA level is. 7.5% minium to 11.5% of the CYA.
Pool School - Chlorine / CYA Chart

3. ## Re: Pool Math and FC?

Originally Posted by firstbase
Pool Math tells me that my FC should be a minimum of 4 with a Daily Goal between 9 and 11 yet the suggest level listed elsewhere on TFP say much lower.. like 3-5. Why is this? What should my FC level actually be?

4. ## Re: Pool Math and FC?

Minimum and target FC are different for SWCG versus non-SWCG. I think that's where you are seeing the differences. Refer to the Chlorine / CYA Chart that Divine Dave linked to in post #2

If your SWCG is operational and you are actively using it to chlorinate the pool use the SWG Pools section of the chart. If manually chlorinating the pool use the Non - SWG Pools section of the chart.

5. ## Re: Pool Math and FC?

Originally Posted by proavia
Minimum and target FC are different for SWCG versus non-SWCG. I think that's where you are seeing the differences. Refer to the Chlorine / CYA Chart that Divine Dave linked to in post #2

If your SWCG is operational and you are actively using it to chlorinate the pool use the SWG Pools section of the chart. If manually chlorinating the pool use the Non - SWG Pools section of the chart.
No, I am using the numbers from SWG chart a well as the Pool Math numbers. Those are the two set that don't agree. My CYA...well, don't get me started on reading that test. Have no real idea what "Until you can't see the dot" actually means. Yesterday CYA read at 78. Today it reads 65. Mor accurte to say "I read it at...". This is another subject/thread though. Lets pretend my CYA is 70 then I should be 7.5% to 11.5% which would be 5-8 FC.

6. ## Re: Pool Math and FC?

It sounds like you are reading the target for non-swg pools in PoolMath.

Mine says this for CYA 70
SWG Minimum: 3 non-SWG Minimum: 5 Daily Target: 8 to 10

Which matches this
FC/CYA Chart

7. ## Re: Pool Math and FC?

Ok, i think i see what you mean.

In PoolMath it shows a SWG minimum, a non-SWG minimum and a target. But the target displays a numbers range for non-SWG. I don't see a target for SWG. Maybe the SWG target can be added at the next update to PoolMath - maybe not. In the mean time, refer to the CYA/Chlorine Chart. Maybe even print that chart out and keep with your testkit.

EDIT:
If your CYA is between 2 numbers on the test vial - round up. So between 60 and 70 - dose for 70. Plus or minus 10 is well within the error margin of the test.

8. ## Re: Pool Math and FC?

CYA is the most subjective test you'll do and it is frustrating. After you do a lot of them you'll feel better but never will you be happy. Just make sure you keep the FC where the Pool Math indicates for your "estimated" level.

9. ## Re: Pool Math and FC?

Originally Posted by Frankhugus
CYA is the most subjective test you'll do and it is frustrating. After you do a lot of them you'll feel better but never will you be happy. Just make sure you keep the FC where the Pool Math indicates for your "estimated" level.
Thanks...so listen to Pool Math not the SWG CYA / FC chart then. Pool Math says 8-10 for my tests w/CYA at 70. Chart says FC at 5 w/ CYA of 70. I'm probably overthinking this..obsessing with the numbers right? How much difference can 4ppm chlorine matter and who can keep it that stable?!?! With South Florida rain, overflow, refilling or South Florida evaporation and refilling, wife mowing the lawn around the pool (into the pool), etc etc etc....hard to keep chlorine and pH at any one level for more than 24 hours.

10. ## Re: Pool Math and FC?

Could always buy one of these if you're really bothered by the test so much - Cyanuric Acid Portable Photometer - HI96722 - Hanna Instruments

11. ## Re: Pool Math and FC?

Originally Posted by JoyfulNoise
Could always buy one of these if you're really bothered by the test so much - Cyanuric Acid Portable Photometer - HI96722 - Hanna Instruments

12. ## Re: Pool Math and FC?

Originally Posted by Jaimslaw
I prefer to spend \$200+ dollars on restocking my beer fridge...

13. ## Re: Pool Math and FC?

Also notice that all you get for the \$220 is the meter and two sample cuvettes. You still need to buy the reagent packs (\$110) and the calibration standards (\$140). The cleaning solution and microfiber clothes are probably a good idea too.

So now you're looking at a \$600 instrument when all is said and done....I'll leave the cost/benefit analysis up to the individual on this one....

14. ## Re: Pool Math and FC?

And it only measures to 80 ppm.

15. ## Re: Pool Math and FC?

Yeah...way too much. Using \$\$ to buy and drink many beers infinintely preferable. Besides, I am able to render myself invisible after drinking a six pack.

16. ## Re: Pool Math and FC?

And I thought making beer disappear was your superpower...

17. ## Re: Pool Math and FC?

Oh, a bunch of FUNNY guys eh?!?!? With my luck I would spend the \$600 only to find out that, after completing the 17 steps to set up and calibrate the thing, you get your result by submerging it in the pool and measuring how deep you have to push it before the black round knob disappears from your sight.

The only superpower I want right now is the super ability to tell 60 CYA from 80 CYA...

18. ## Re: Pool Math and FC?

Just dose for 80 and be happy. It is only 2ppm more fc. More FC is always better than less. It is safe to swim up to shock level for your CYA. It is not safe to swim below minimum for your CYA. FC/CYA Chart

Beer fridge?
CAM00125.jpg

19. ## Re: Pool Math and FC?

Dump everything out on the top shelves and refill with more Shiner Bock!

20. ## Re: Pool Math and FC?

Originally Posted by Griswald
Dump everything out on the top shelves and refill with more Shiner Bock!
I'll take that Boddington so you don't have to worry about it and you can keep that clear bottled stuff...

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