First test results need feedback

[DMand]

20X40 inground pool, chlorine, DE, 36000 gal, water temp 78:
FC = 8.5
CC = 0.5
pH = 7.4
Alk = 130
CYA = 30
Any suggestions?

[CarlD]

If you are using Ben's kit, or the Taylor 2006, or the Leslies FAS-DPD, re-run the FC and CC tests using the 25ml line and counting drops as .2ppm, not .5. If your CC is less than .5, don't worry about it and go swimming. Remember: you don't know if it's .1, .3, or .5 for your CC--it's just .5 or less, but more than 0.

If it is .5 of cc:

Add bleach to shock up to 15ppm FC, see if CC disappears. If it doesn't, it's not a big deal, go swimming. I don't think it will matter since your FC is 8.5 with a CYA of 30.

[DMand]

I am using the PS234 kit. I did as you suggested and filled tube with pool water to the 25ml mark instead of 10 ml. But I need more detail. I put in only 1 scoop of the powder, do I need to add more than 1 scoop? I added 46 drops of FAS-DPD #2 until sample turned clear. How do I calculate the FC? I added 5 drops of FAS-DPD #3 and sample stayed clear.

[CarlD]

I am using the PS234 kit. I did as you suggested and filled tube with pool water to the 25ml mark instead of 10 ml. But I need more detail. I put in only 1 scoop of the powder, do I need to add more than 1 scoop? I added 46 drops of FAS-DPD #2 until sample turned clear. How do I calculate the FC? I added 5 drops of FAS-DPD #3 and sample stayed clear.

You only need enough powder to turn the water pink. More won't hurt but is wasted. 46 drops are .2 per drop. Every 5 is 1ppm, so you have 9.2ppm of FC. If 5 drops of #3 leave the water clear and it doesn't have even a hint of pink, you have no measureable CC. If it's clearly pink you add drops till it goes clear. If you aren't sure, sit the tube on a white surface and see if it has a pink tinge. If you think it does and add 1 drop of #2. If it doesn't change at all, try another until it changes, or until you are sure it won't (3 drops at most). If it changes, each drop is .2 ppm of CC.

[DMand]

Thank you for the explanation.
Is 9.2 too high for my CYA of 30? Should I do something now or wait for it to lessen? I added chlorine the past few days because of high pool use.

[Sherra]

9.2 is a bit high for maintenance...it's still alright for swimming, but it may fade your suit. I'd let it drift down to the range listed below. Leave the pool uncovered for a day or two and it'll drift down soon enough.
__________________________________________________ ___
Ben's 'best guess' FC/Stabilizer table for algae free operation of OUTDOOR pools -- as of July 2003 --

Use the info in this chart to help you figure out what levels of chlorine you need to maintain in your pool based on the amount of CYA (cyanuric acid, also called stabilizer) that you have in your pool. (FC = free chlorine)

Stabilizer . . . . . . Min. FC . . . . Max FC . . . 'Shock' FC
=> 0 ppm . . . . . . . 1 ppm . . . . . 3 ppm . . . . 10 ppm
=> 10 - 20 ppm . . . . 2 ppm . . . . . 5 ppm . . . . 12 ppm
=> 30 - 50 ppm . . . . 3 ppm . . . . . 6 ppm . . . . 15 ppm
=> 60 - 90 ppm . . . . 5 ppm . . . . . 10 ppm . . .. 20 ppm
=> 100 - 200 ppm . . . 8 ppm . . . . . 15 ppm . . .. 25 ppm