SLAM question

[rabbet]

I'm on the on the fourth day and realize I've made several mistakes. Here are the readings from day one:
pH 7.7 (first mistake)
FC 4
CC <.5
TA 90
CYA 30
CH 275

I think I should have lowered the pH, but it's too late now.

I had persistent algae, which I assumed was mustard because it was there in spite of correct chlorine and pH levels. It congregates along seams and crack repairs, both of which are a bit rough, and at the right angle corners where the sides meet the floor. So I used the MA number for the SLAM which was 19 ppm, instead of the shock number which would have been 12. So the question is, should I lower the FC to 12 and continue until the FC holds overnight, and then raise the FC to 19 for 24 hours after that? The water is already clear and today the CC was 0 for the first time. I do notice there is a brief white cloud when I brush. Is that dead algae or live algae? I also realized yesterday that I hadn't left the poles, brushes, etc in the pool.

I'm also wondering if it's foolish to go through all this right before closing the pool.

I'd appreciate any guidance.

 

[tim5055]

I'm on the on the fourth day and realize I've made several mistakes. Here are the readings from day one:
pH 7.7 (first mistake)
FC 4
CC <.5
TA 90
CYA 30
CH 275

I think I should have lowered the pH, but it's too late now.

I had persistent algae, which I assumed was mustard because it was there in spite of correct chlorine and pH levels. It congregates along seams and crack repairs, both of which are a bit rough, and at the right angle corners where the sides meet the floor. So I used the MA number for the SLAM which was 19 ppm, instead of the shock number which would have been 12. So the question is, should I lower the FC to 12 and continue until the FC holds overnight, and then raise the FC to 19 for 24 hours after that? The water is already clear and today the CC was 0 for the first time. I do notice there is a brief white cloud when I brush. Is that dead algae or live algae? I also realized yesterday that I hadn't left the poles, brushes, etc in the pool.

I'm also wondering if it's foolish to go through all this right before closing the pool.

I'd appreciate any guidance.

I would say the stuff you are seeing when you brush is either dead algae or dirt/pollen/plaster dust.

If you have brushed well and don't see algae in the seams like before do an Overnight FC Loss Test (OCLT) to see if you can end the SLAM. The issue of not lowering the pH and conducting the SLAM at MA levels the whole time are water under the bridge.

Nope, do it now so it's not a bigger problem in the spring.

 

[pwrstrk]

If your seeing algae in those areas it could be from poor circulation in those areas. Might try brushing there more often.
I think your ready to try an OCLT. ?

 

[rabbet]

Strangely, the place where I see the algae is where there is the most circulation.

 

[pwrstrk]

What is your normal FC target level ?

 

[rabbet]

FC 4

- - - Updated - - -

If you have brushed well...

I never think my brushing is adequate.

 

[pwrstrk]

For the CYA level of 30 you should target 5-6. That's a little more room so you don't fall below 2. You may have dipped to low with your FC and a little algae starts to form, but you keep it from a full blown outbreak.
When you open next year I'd go with a CYA level of 40 and target your FC level at 7 and never below 3. ?

 

[rabbet]

For the CYA level of 30 you should target 5-6. That's a little more room so you don't fall below 2. You may have dipped to low with your FC and a little algae starts to form, but you keep it from a full blown outbreak.
When you open next year I'd go with a CYA level of 40 and target your FC level at 7 and never below 3. &#55357;&#56846;

I was going by the chlorine/CYA 'Best Guess' chart and Chemgeek's chart.

 

[pwrstrk]

Pool Math will suggest different levels that I use in my pool. Never had algae at anytime. My CYA level is 40 and I target FC at 7. That gives me 4ppm wiggle room from FC burn off and swimmers so I don't fall below my min level of 3. ?

 

[BoDarville]

I follow the same process as pwrstrk. During the summer swim season, I target the high end of the FC range suggested by PoolMath . Between sunlight and the warmer water temperatures and higher bather loads of summer, the extra headroom provided by maintaining FC at the upper end of the recommended range has kept my pool algae-free. Haven't had to shock/SLAM in I don't know how many years.