Total chlorine always more than 0.2 of FAC

Hello everyone!

I’ve been having trouble with my total chlorine always being higher than my FAC since maybe 1-2 months ago. Not sure what is going on. I’ve searched everywhere for an answer but nothing really has helped. I recently slammed the pool as I was fighting a small algae issue that kept coming back every few days. Used a ton of cal hypo these last few days. It feels like I’ve gotten rid of the algae. Now I’d like to get my FAC and TC between the 0.2 range. Hoping someone here can help :crossed_fingers:t3:

I tested the water this morning and here is what my accublue test results said:

Free Chlorine - 9.46

Total Chlorine - 11.67

pH - 7.5

Total Alkalinity - 92

Calcium Hardness - 331

Cya Acid - 52

Iron - 0

Copper - 0

Phosphates - 36

My in-ground pool is 30,000 gallons and it is concrete.

Thanks everyone!

Hello Badeh2,

Except for the free and total chlorine numbers everything else is within the acceptable range. A total chlorine level higher than the free chlorine tells me that you still have organics in the water eating the chlorine as fast as you put it in the pool. I suspect you haven’t fully killed the algae in the water.

If you had effectively slammed the pool you would know that the algae is dead because part of the slamming process is the overnight chlorine loss test(OCLT).

Tell me what you did to "slam " the pool.



Hi J,

I kept my chlorine levels between 15-20 ppm for about 3 days. I actually forgot to do the overnight chlorine loss test (doh!). Do you think it’s too late to do it now? Yesterday late afternoon my fc level was at 6.15 and my tc was at 6.74. I didnt check my levels this morning

So after adding granular chlorine for few days, i actually never saw any dead algae go to the bottom of the pool floor. I did backwash a couple times when my sand filter pressure was higher than normal. Should I have vacuumed the pool floor to waste even if I didnt see any dead algae on the pool floor?

Thanks so much for your help! 


You can always do a OCLT test. What kind of test kit did you use for the chlorine readings?


I have been using leslie’s accublue water testing machine since last year. I’ll do the OCLT tonight and report back tomorrow! Thanks so much!

If you want an accurate OCLT you need to take a chlorine reading as close to sundown as possible and then take another reading early the next morning before the sun gets on the pool. If the fee chlorine loss is more than 1 ppm you need to continue the SLAM. Just as important is the combined chlorine (CC) level.

Your last test numbers show a CC reading of .59 ppm (TC=6.74 ppm minus FC=6.15 ppm = .59 ppm CC). Anything over .5 ppm indicates there are still organics in the water. That being said, pool store testing equipment is not known for it’s accuracy or reliability…unless they are using the manual reagent drop titration method.

My strong recommendation would be that you get a good, reliable FAS/DPD test kit. Like the Taylor K2006 or the TF-100 kit. Both kits use Taylor reagents and both kits will perform the full range of tests needed for proper water analysis. The FAS/DPD chlorine test will detect chlorine up to a level of 50 ppm which is invaluable when doing a SLAM of the pool.

The kits are a little expensive but will more than pay for themselves with the amount of money for gas, time and un-needed chemicals going to the pool store for the “free” water test will cost you. And you will be able to test your water anytime.

One last thing. For the CYA level in your pool (52 ppm) you should have 6 ppm of FC in the water. And it should never fall below 4 ppm. If you do a OCLT and the FC loss is 1 ppm or less and the CC is .5 ppm or less and the water is clear, then maintaining a 6 ppm level of FC in the water should take care of your CC issues.


The leslies accublue is a membership now for 50$ per month but you also get a 50$ credit each month to use at leslies. So you get a somewhat accurate fancy water testing machine at home for free but i have heard people say these machines arent always accurate. I did show having phosphates at 36 ppb 2 days ago but a day ago it gave me a 158 ppb reading lol.

I just tested my water and i got a reading of:

FC 3.59

TC 4.13

Ph is 7.5

CYA 51

alkalinity 90

CH 315

phosphates 165

So tomorrow morning if my FC is less than 2.59 then I need to continue to SLAM?

“So tomorrow morning if my FC is less than 2.59 then I need to continue to SLAM?”

If you are losing more than 1 ppm of FC overnight OR if the CC reading is more than.5 ppm OR both, you still have organics in the water and my recommendation would be to continue the SLAM.

There is an article at InyoPools about slamming your pool. There is a more in-depth article about it Here


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Good morning! My FC is still 3.59 this morning and my TC shows a reading of 4.09! Looks like I didnt lose any FC and my TC lowered a bit. CC is now exactly .5

That’s good news. I’ll bet if you keep the FC at the level your CYA dictates (6 ppm) the CC will continue to drift downward.