CYA Level for Slam

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M

Mach2Mick

0
Jul 18, 2013
6
Walton, KY
I have an algae problem and a party in one week. I just discovered this forum and Pool School so I'm trying to get up to speed very rapidly. I am planning to begin Slamming my pool this afternoon and my question is this:

CYA is currently below recommended level. Should I leave it there for Slamming purposes (from what I've read on Pool School it will require less chlorine) or adjust it to recommended level prior to beginning Slam?

My TF100 kit arrives today so the levels I have to share are from two sources, Aquachek and a Swimline Hydrotools test kit.

Aquachek (readings as best I can tell)
TH 100
TC ~2.5
FC ~2.5
pH 6.9-7.0
TA <80
CYA 0-30

Drops test kit
TC ~2.0
FC ~2.5
pH 7.3-7.4
TA 40-50

These tests were performed this morning. I added 10 lbs Sodium Bicarbonate to boost TA to recommended level.

27,000 gal is an estimate. I'll be measuring for accuracy this afternoon.
 
:wave: Welcome to TFP!!!

It is usually good to have the CYA around 30ppm for the SLAM process. While the shock FC level is a little higher with the higher CYA, you will lose less FC to the sun and will thus actually use less bleach during the day. You certainly need > 0ppm of CYA because if you have none in the pool, you will lose 50% of the FC to the sun every hour in the middle of the day.

Good thing your TF100 arrives today ... as you are going to need it to get the pool cleared up by the party ;)
 
Test kit arrived yesterday and demonstrated how useless the test strips really are.

FC 3
CC .5
TA 90
CH 90
CYA 40
pH 7.2

Began slam process last night.

FC 34 (decided to use the yellow algae numbers just in case and overshot a little)
CC .5

This morning no appreciable difference in color/clarity

FC 29
CC .5

I was expecting the CC to have gone up by the amount the FC came down. Shouldn't the CC be going up if the chlorine is killing the algae? I obviously don't completely understand this stuff yet.

Also, I measured the pool and have a much more accurate estimate of 22,000 gal for pool size.
 
Your FC SLAM level is a bit high. Chart tells me 20 ppm FC for CYA 40. I think you would be better off maintaing closer to that number.....34 is a bit higher than we suggest.

I was expecting the CC to have gone up by the amount the FC came down. Shouldn't the CC be going up if the chlorine is killing the algae?
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The amount of CC's in your pool cany vary during SLAM. Don't worry when that happens.

What's important is that CC's get down around .5 ppm as your water clears and you get near the end of the process.

What does your water look like?
 
I understood the target FC to be 24 for yellow algae. I dosed to 34 by mistake using my previous estimate of pool size of 27,000 gal. After measurement and calculations I determined my pool size to be 22,000 (not a standard shape, rectangular deep end and oversize circle at shallow end with steps). Also, I had half a gallon of chlorine left after I used the amount the calculator called for (for 27,000) so I dumped it in rather than save it.

Water is fairly cloudy and greenish. I can still just barely make out the main drain after brushing.

Also, yesterday before beginning the SLAM I vacuumed the visible algae. I backwashed expecting to see a fair amount in the waste water. there was hardly any. I am assuming that means its all stuck in my filter. Will that release after it dies?
 
I am assuming that means its all stuck in my filter.
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No. That's why you backwash. Don't worry that you didn't catch much.

Backwash when you see your filter psi go up 25% or so from normal. You'll get there.....don't second guess yourself and keep following the process....it works.
 
3rd morning after starting slam and pool is completely blue and almost completely clear. I added Cl right before bed last night so I have to wait until tonight for OCLT but judging by FC level this morning I'm expecting to pass. I got some DE to add to my sand filter to help with the clearing.

Any advice on transitioning from SLAM to maintenance?

4 days til party and it appears I'm in great shape! I can't fully explain how good it feels to perform a calculated procedure with the pool, expecting a certain result, and then getting that result. My days of blindly following pool store pretenders are over! Thank you so much Dave and other posters!
 
Just make sure you meet all 3 criteria before ending the SLAM. When your finished just let the FC level drift down and maintain your FC level in range with your CYA level. That'll be your maintaince levels.

Good job !!


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Any advice on transitioning from SLAM to maintenance?

4 days til party and it appears I'm in great shape! I can't fully explain how good it feels to perform a calculated procedure with the pool, expecting a certain result, and then getting that result. My days of blindly following pool store pretenders are over! Thank you so much Dave and other posters!
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Transitioning to maintenance is as simple as allowing your FC to drift down on it's own from SLAM level to normal (3-5 ppm with CYA 40). Then make absolutely sure you never let FC go below that and you will have a crystal clear pool for the remainder of the season.

I understand completely about the satisfaction of knowing what and how much to put in your pool and getting the expected result.

The credit goes to you for your willingness to learn what we teach and then turning your knowledge into action.

There are no graduates from BBB school because the learning never stops but you are for sure a BBB'r.

Nice work :goodjob:

(reminder - keep that FC up at 3-5 ppm the rest of the season :mrgreen: )
 
Mach2Mick said:
3rd morning after starting slam and pool is completely blue and almost completely clear. I added Cl right before bed last night so I have to wait until tonight for OCLT but judging by FC level this morning I'm expecting to pass. I got some DE to add to my sand filter to help with the clearing.

:-D

Any advice on transitioning from SLAM to maintenance?
After you pass the three tests (see red lines in my sig) allow the FC to drift back down to maintenance level. With 40 CYA, keep FC between 3 and 7 and never below 3.
4 days til party and it appears I'm in great shape! I can't fully explain how good it feels to perform a calculated procedure with the pool, expecting a certain result, and then getting that result. My days of blindly following pool store pretenders are over! Thank you so much Dave and other posters!
It is a great feeling when you know you are now in control of your pool. :goodjob:
Can we see a pic of the pool? Welcome to the forum :wave:
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