SLAM: Why SO Much Chlorine at Opening?


Well-known member
Aug 25, 2013
Hi and happy 2018 pool season. I'm in the Northeast and opened the pool a week and a half ago (I do a short pool season)

This is my second year following the TFP method. But I was hoping if some of the seasoned members could give me some ideas as to why I am using SO MUCH liquid chlorine during this SLAM? I purchased 12.5% "Super Shock" from Ocean State Job Lot. It was manufactured mid-May. I tested the chlorine content and it actually diminished a little. So the result is it is really approx. 10% chlorine.

1.) When removed the cover, the water was clear. The FC registered Zero. I vacuumed and have vacuumed since.
2.) The CYA was unfortunately high at 60 (I was duped to add CYA. A pool store did the CYA reagent/mix test, just like I would...but in hindsight I don't think they shaked the tube they said my CYA was low)
3.) But CYA is back down to approx. 40-45 (I removed water and refilled)
4.) The sand filter has been running 24/7. I backwash, rinse, etc. Sure it was greener backwash at first but has dissipated much.
5.) I've gone through TWENTY or so bottle of the 10% liquid chlorine. And it still isn't passing the overnight FC drop test!

The pool doesn't seem to be hiding algae anywhere. Things are clean.

So...any ideas?

AND RELATED >>>> And ideas to speed-up the SLAM process? Ex. Would it be worth it to "NUKE" the pool immediately, like if the recommended SLAM FC level is raise it to 30 or 40? Will that help speed the process? Just looking for some ideas.

Thanks as always!


Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
Consider your CYA at 50. Anything over 40 is 50.

How about posting a full set of test results?

If you put extra chlorine in, you just lose that much more.

Maddie :flower:


Platinum Supporter
TFP Guide
Jul 30, 2014
Monmouth County, New Jersey
Can you provide a timeline? You opened the pool late.

A few questions:

1) How was the water upon opening? You stated clear, but backwashing shows green!
2) How many gallons did you put in originally?
3) Did you run the filter all day/night and brush/vacuum/backwash if necessary?
4) Did you track your bleach consumption daily?
5) Did you track your TC loss daily?
6) At what day are you now? Where exactly are you during the SLAM process? Condition of Water?
7) At what levels are you performing the overnight test? If you are way over 10 ppm, allow the levels to drop down under 10 and perform the test. No more than 8-10 hours apart. Test at 10 p.m. and no later than 8 a.m. before the sun starts beating down on the pool.

Pictures are always great! Also, you stated pool store testing and I see you have your own test kit. I have to ask why you even entered the pool store? keeping track of daily activity helps track daily events to determine if you are making progress.


Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
Tucson, AZ
On tapatalk I can't see your signature or bio.
How many gallon pool do you have?
Click their user name and you can see the start of their signature. Although I would suggest that it is not up to the OP to again provide information available to you if you were not using an alternate app ;)