Trying to SLAM but FC not rising

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danvillepool2014

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Jun 12, 2014
9
Danville
I'm SLAMing and am concerned I will add too much CYA because I've read it takes a while to show up.

Pool is pretty green.

Test kit K2006
FC 1.0
CC 2.0
pH 7.4
TA 80
CH 500
CYA appears 0 (it is not even 30 and that is the lowest number on my test kit).
I added enough CYA two days ago to supposedly raise it to 30 but it is not showing up yet. I didn't do the sock method as I hadn't read that part yet (doh!).

I've read I am supposed to proceed with the SLAM as if the CYA is there. The calculator is directing me to add about 128oz each time I check the FC, but that doesn't seem to raise FC by more than 0.5 at a time. It seems that I should be adding a lot more chlorine to get to the recommended 10FC.

Please advise what you would do. Many thanks.

18,000 GL, IG, plaster, cartridge, Starite pump
 
Last edited:
Welcome Danville.

Do you have an inground or an above ground pool? If you could put your pool specs in your signature, it would help.

Ok... We need to SLAM to the level you raised your CYA and just assume it's in there. So how much did you raise it to? A CYA of 30 will require a SLAM of 12pm. Plug it into Pool Math. Add the chlorine and check it within a half hour to see if it's holding. If it's not holding, you add more to bring it back up to 12 and keep dosing the pool until it holds. Doing it at night will take the sun out of the equation and help you hold an FC reading at least a little longer than in the day time as 2 things consume FC and that is sunlight and organics. :goodjob:

Post back any questions.
 
It takes about a week. :goodjob:

Use settings below the Pool School button, top right of every page to save your signature. :cool:
 
Do you remember what your CYA level was last year by any chance?
 
Last year I remember it got super high from shocking that the pool store told me to do. I think it got to about 100 before I realized my error. I haven't drained but have filled a little here and there since then. How would it come down so low without draining it? Thanks.
 
Isn't this where Richard320 usually posts the picture of a Clorox tanker truck ?

OK, so one *possibility* is that the CYA got converted to ammonia over the winter by bacteria. If so then (a) you don't want to add any more CYA than you have in case it gets converted too, and (b) each time you add bleach it's going to get used up almost immediately attacking the ammonia, and IIRC the total amount of bleach required until FC starts to go up will be roughly the same as the CYA level you had last fall. If that is the case, then you'll need to add 12 ppm worth of bleach ~8 times before the FC starts going up and the bleach starts working on algae rather than ammonia.

The good news is that whether you have ammonia or not, your actions are exactly the same at this point... keep adding enough bleach to get to 12ppm, check FC level after running the pump for 1/2 hr to 1 hr, and add more bleach if needed. At some point the FC will start to go up, and at that point your pool will start getting less green.

EDIT -- for what it's worth, when I asked PoolMath how much 8.25% bleach I needed to raise an 18,000 gallon pool from 0 ppm FC to 12 ppm FC it told me 326 oz, or 2-1/2 gallons of bleach. Sounds like you are seeing something different -- can you check your numbers ?
 

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That is super helpful. I'll get a ton of bleach this weekend and an ammonia testing kit and will report back.

You are right that my numbers were off. I am using 10% bleach so I should have stated that PoolMath directs me to add about A COUPLE of 128oz jugs at a time. Thanks again.

- - - Updated - - -

I don't think there is a way to bypass the filter but I could remove the cartridges temporarily I suppose. But isn't it inevitable that I get stuck with a ton of algae in the cartridges anyway? Or does the SLAM sort of change the algae to some form that doesn't clog up the cartridges? Really appreciate all the advice.
 
You're absolutely right that you are going to have to filter it out anyways. I was just thinking that at the moment algae is still growing and will keep doing that until you can keep the FC level up, so bypassing the filter now would let you concentrate the annoying filter/clean/filter/clean/filter/clean phase into a smaller number of days. I have a cheapo pump/filter that I have to take apart if I want to clean the filter -- I don't know if you have to do that or if there is some "move the handle to position B and flush all the gunk out" option.

But yeah, one way or another you are going to have to filter it out.

Another thing to consider would be putting a knee-high stocking or something over the skimmer basket to help catch algae before it gets to the cartridge. You'll need to check it frequently but might be easier to clean than your cartridge -- all depends on your specific equipment I guess.
 
In an ammonia slam you can test and dose as often as every 30 min. Once your CL starts to hold ( 6 ppm) go to hour intervals. Keep assuming 30 on the cya and target 12 for the CL.


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I was suspecting ammonia too. You should hold off with the CYA and kill the ammonia off first. You should hit the pool very hard, fast and consistently through out the day with the bleach. You will need that tanker truck of bleach because the ammonia will use up a lot of it! Please do post the ammonia test results. Sounds like your pool had a party this winter and now it's pretty sick. Ain't nothing good ole bleach can't handle! :goodjob:
 
Here's the results from my ammonia test and SLAM:

10:30AM
Ammonia - 8PPM
FC 0.5
CC 1.0
ADDED 8 JUGS OF 10% BLEACH AT 128 OZ EA

12pm
Ammonia somewhere between 4-8PPM (not a precise test kit)
FC 2.5
CC 1.5
ADDED 11 JUGS OF 10% BLEACH AT 128 OZ EA

12:45pm
Ammonia 0.25
FC 5
CC 0.5
ADDED 1 JUG OF 10% BLEACH AT 128 OZ EA

1:40PM
Ammonia 0.25
FC 6
CC 0.5
ADDED 4 JUGS OF 10% BLEACH AT 128 OZ EA

2:40PM
Ammonia 0.25
FC 20
CC less than 1

Pool smells awful and looks blue. I have been keeping the cover closed in between tests all day. Would opening it help the scent improve and lower the FC quicker? Thanks.
 

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