I have some test results and need to know if I can shock or SLAM my pool.

HeatherEG

Member
Sep 10, 2021
11
Indiana
Pool Size
15000
Surface
Fiberglass
Chlorine
Liquid Chlorine
I finally got my K-2006c test kit and ran the tests. Here are the results:
FC .8
CC 3.2
Alk 220 (250 when I did the high method)
Calcium 475
Ph 7.6 or 7.7 (it was in between)
CYA 200

It's an old pool and aside from the 1/3 water change we just did, I don't know if the previous owners ever did a water change so there is a lot of stabilizer, calcium and phosphates ( 3847 by pool store computer). How much liquid chlorine would I have to add all at once to shock this pool? I need to learn more about the SLAM process, but it sounded like it used a lot of chlorine.

We talked about doing an almost complete water exchange using the tarp method, as the pool water truck driver mentioned he had done that before, but with the pump rental, tarp and water, it would run us about $700 and right now the pool is clear and beautiful, so it's hard to justify spending that amount of money. I have let go of my trusted Trichlor and am using only liquid chlorine. With the cover, it holds its level pretty well for days.

I know I don't have much free chlorine. What would you suggest? (15,000 gallon, fiberglass pool, circa 1997, newer Pentair pump, old Jacuzzi Triclops filter and Hayward H200 heater, with an automatic, dark, opaque cover that's on most of the time).
 

borjis

LifeTime Supporter
Aug 19, 2014
3,491
Pacific NW
The cya at 200...way too high to slam. Did you do a dilution test to get that number?
It really needs to be knocked down to at least 50 before you slam. 30 would be even better. chlorine can't do it's job when it's that high.
 
  • Like
Reactions: Mdragger88

Msch99

Gold Supporter
Bronze Supporter
Jun 11, 2018
1,009
Verona, MO
Between rock and hard place..,cost a ton to try and slam, not even sure you can with CYA 200.
Betting experts recommend exchanging to at least 70 or 80 first.

Phosphates don’t really matter, proper chlorine levels kill algae.
 

HeatherEG

Member
Sep 10, 2021
11
Indiana
Pool Size
15000
Surface
Fiberglass
Chlorine
Liquid Chlorine
The cya at 200...way too high to slam. Did you do a dilution test to get that number?
It really needs to be knocked down to at least 50 before you slam. 30 would be even better. chlorine can't do it's job when it's that high.
Yes, I did a 50-50 solution pool water with tap water, then used half of that to get 100 which doubles to 200.
 

HeatherEG

Member
Sep 10, 2021
11
Indiana
Pool Size
15000
Surface
Fiberglass
Chlorine
Liquid Chlorine
Check out the no drain water exchange portion
Thanks, I'll look at it again to see if I missed anything. The drain high, fill low, or vice-versa method sounds like you would eventually get a lot of mixing. If we were just exchanging a portion, I would be more apt to try that one, but for a near total exchange I don't see a lot of alternatives to the tarp method, considering I have a fiberglass pool. My biggest concern about that method is breaking the full tarp away from the side of the pool to remove it when you're done. I remember the poster said he had to really work to get a hose shoved down there, so I think I would have a fill-garden-hose already in place before starting. Still, I might write to him and see if he has any pointers. At any rate, it looks like that will have to wait until next spring as we are so close to closing now.
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
2,969
Spring Valley, NY
The no drain exchange when done properly can work 100%. It's all in the calculation of how many gallons and the gph fresh water versus expelling the old along with the delta T which means the differentiation of water temperature between the fresh water and the old water. Done right works all the less the danger of floating the pool. I like to heat the pool water up high so that the temperature split is always a sure split.
 
  • Like
Reactions: PoolStored

HeatherEG

Member
Sep 10, 2021
11
Indiana
Pool Size
15000
Surface
Fiberglass
Chlorine
Liquid Chlorine
The no drain exchange when done properly can work 100%. It's all in the calculation of how many gallons and the gph fresh water versus expelling the old along with the delta T which means the differentiation of water temperature between the fresh water and the old water. Done right works all the less the danger of floating the pool. I like to heat the pool water up high so that the temperature split is always a sure split.
I do like my pool on the warm side, so if done quickly, it could work. But isn't there another variable besides water temperature, like water hardness?
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
2,969
Spring Valley, NY
Water temperature is key here so the fresh fill sits lower then the old water. The warmer you start off with the better the exchange will be at least that's what I have been doing and works well all the time. Also POP (pool owner patience) is very important too ;). Follow the T and the results will be there.