Just got my FAS-DPD and don't understand result combined Cl


Jul 16, 2018
Pran Buri
I tested free chlorine in my pool and result was 3 ppm.
Then I tested combined chlorine and water was colorless after 3 drops.
I thought, but then it started to be pink again, I put drop 4 in.
Then it started to be pink again. After 13 drops I stop!
Why is it like that?

Other facts to know:
volume 43 m3 (11 500 gallon)
Salinity is high, 5.
I have a chlorinater that should give 15g/hr
water temp 30 C, 86F
PH 7.7
CH 170
TA 50
CYA <30

This is the first time I have a good test kit, before only drops for PH and chlorine. I have to read and learn and see if I can get CH, TA and CYA to be ok.


Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
Tucson, AZ
The test is complete when the sample first goes colorless. It is normal for the sample to turn back pink if you let it sit for too long.

Add powder. Count drops to go clear (roughly 1 drop per second). That is your FC. Add r0003. Count drops to clear. That is your CC. Done.

TA and CH and pH are currently fine. Only CYA seems to need to be adjusted higher.