Post-Slam Post Mortem

[elecsheep9]

I'd been battling an apparent algae bloom for about two weeks. There was green on the floors, but the pool remained clear. I'd dump shock powder into the pool once a week and it seemed to keep things in check.

But after some heavy rains mid-week, by Thursday-Friday, it became apparent that the algae was winning the battle. So Friday afternoon, I started a SLAM.

My initial CYA reading was around 50 or so, so I went for a Chlorine level of about 20-21. My local supermarket (of all places) had liquid chlorine (the pool supply stores don't even have it), so I was able to use that.

Kept it at SLAM levels Friday afternoon and all day yesterday (even with more of a downpour increasing the pool level by about an inch.)

By this morning, the green was all gone, the water is clear, CCs were 0, and a rough version of the Overnight Test showed a drop of about 2 ppm FC after about 2 hours of sunlight.

The pool like nice and enticing again! Thanks for the help.

However, as I was doing all of the tests just now, I determined the CYA level to be about 75, not the 50 that I had initially determined. But the method seems to have worked regardless.

FC/TC is down to 15pm (still 0 CC), PH is 7.8, Alkalinity is 60.

With a CYA of 75, the pool is good to swim in now, yes?

 

[mknauss]

With a CYA of 75, the pool is good to swim in now, yes?

Yes.
Your CYA should be recorded as 80. SLAM level FC is 31 ppm.
Do not stop short on the SLAM Process

 

[elecsheep9]

Given that I probably SLAM-ed at a lower than prescribed level (I never was much for basketball), should I keep SLAM-ing even though everything looks/reads good?

 

[mknauss]

Did you pass the three criteria?

 

[MITBeta]

rough version of the Overnight Test showed a drop of about 2 ppm FC after about 2 hours of sunlight.

You need to pass a good Overnight Chlorine Loss Test to call a SLAM complete, and then many people will keep up SLAM levels for another day or 2 for good measure.

 

[elecsheep9]

I didn't do the most precise OCLT. I was at 21 at around midnight. Then at 8am (about 2.5 hours after sunrise) I was at 19. Both with 0 CC. Water very clear.

 

[MITBeta]

It's easier to stay at SLAM level and be 110% sure you eradicated all algae by passing a good ONCL test (or 2!) than to let FC drift back down, start having issues, and have to run another SLAM. Plus, you get most of the chlorine addition back on the back side of the SLAM as it takes several days to drift back down.

 

[elecsheep9]

It's easier to stay at SLAM level and be 110% sure you eradicated all algae by passing a good ONCL test (or 2!) than to let FC drift back down, start having issues, and have to run another SLAM. Plus, you get most of the chlorine addition back on the back side of the SLAM as it takes several days to drift back down.

You're the angel on my shoulder. AND NOONE LIKES THE ANGEL ON THEIR SHOULDER! LOL.

I ended up brushing the bottom of the pool and did see a little bit of cloudiness kicking up from the clean looking bottom. So I am continuing the process (this time at 31ppm). I'll run a proper ONCL tonight.

Just when you think you are out, they pull you back in!!!

 

[Newdude]

Just when you think you are out, they pull you back in!!!

Don't forget...... finishing and maintaining the SLAM for a few more days is SO much easier than starting a new SLAM.

There is zero harm in going too long but WAY too much to lose by ending early.

 

[elecsheep9]

Don't forget...... finishing and maintaining the SLAM for a few more days is SO much easier than starting a new SLAM.

There is zero harm in going too long but WAY too much to lose by ending early.

Try explaining that to a 5 year old and a 7 year old.

 

[mknauss]

Try explaining that to a 5 year old and a 7 year old.

You can safely swim in a pool as long as the FC is above the minimum and at or below SLAM level based on your CYA. You must also be able to see the bottom of the pool in the deep end of the pool.

 

[Newdude]

Try explaining that to a 5 year old and a 7 year old

Pool store way = ‘dump and pray’ and because you don’t know where you are and what’s safe you need to stay out.

TFP = know *exactly* where you are, what you did and what it will do. So it’s always safe. You only need to see the bottom clearly for swimmer safety