My first SLAM (hope it's my only SLAM :-)

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needsajet

needsajet

TFP Expert
LifeTime Supporter
Jan 4, 2016
5,392
Sydney, NSW, Australia
Pool Size
44000
Surface
Plaster
Chlorine
Salt Water Generator
Big storm, tons of organics in the pool, vacuumed, brushed yesterday and all looks well, BUT... I've been wanting to learn SLAM, so here goes.

CYA 60 (last time was 70), so I'm going to use FC 28 as my target from Pool School - Chlorine / CYA Chart

pH 7.6, so I added enough MA to get to 7.0 or 7.1 (so I won't have to worry about pH while SLAMing)

FC 5 so I added almost 2g (8L) of 12.5% pool chlorine to get to 28

I used http://www.troublefreepool.com/calc.html to figure out the quantities

Then I brushed the heck out of the pool. It hasn't turned cloudy so far, and I noticed an insect that had switched from Australian crawl to backstroke.
 
From crawl to backstroke huh? ha. Very nice. You're on your way! Minor correction .... CYA of 60 = SLAM/shock FC of 24; CYA of 70 = SLAM/Shock FC of 28. Use whichever one is applicable. You sound to know what to do from here (Pump running 24/7, scrub, clean filter, etc) . Now you let the bleach and time do its job. :cheers:

Oh, and SWG turned off. :)
 
Thanks, all. So far so good. I re-read the SLAM instructions in Pool School and I can't see the instruction to turn the SWG off. It says to use it to help maintain the SLAM level and it was super-sunny here today, so I left the SWG on to keep the level up. I'm planning to set it to 0% for overnight. I wasn't going to do an OCLT for the first night, but haven't decided for sure yet. Just thinking through how much reagent I have and will need.
 
The main purpose is to have the SWG off when you perform the OCLT. I don't think that it hurts to run your SWG to maintain the SLAM but obviously with the view that it only adds chlorine slowly and in conjunction with further additions of liquid chlorine.

Just make sure you remember to turn off the SWG when you go the OCLT.
 
From the SLAM page:
If you have a salt water chlorine generator, chlorine tablet dispenser, injection pump, or Liquidator, you will still need to use another chlorine source for SLAMing. All of these devices are designed to add chlorine slowly and steadily over many hours. To kill algae or lower CC, you need to put in lots of chlorine all at once. The SWG, tablet dispenser, injection pump, or Liquidator can be very helpful in the follow up stages to maintain FC at shock level, but for the initial couple of chlorine applications, you need to use another chlorine source.
Click to expand...

The other reason note really specified is since manual dosing is the primary method (bleach), and a SLAM requires such a high FC level that most SWGs aren't designed to maintain anyways, leaving it off saves stress on the unit to help reduce cell service life.
 
I scrubbed twice and backwashed yesterday afternoon and tested/added chlorine three times to replace what was getting burned off by the sun. On the first test, the FC was lower than the calculations, so some burned off by sun, but I also think the first jug of chlorine I used might have been a bit worn out. It was a lighter yellow than the new jug.

I turned the SWG off last night and tested for the start of OCLT. Results were FC 27.5 and CC <0.5. It rained a little bit overnight and there were a few leaves and two dead caterpillars. This morning I got FC 26.5 and CC <0.5. Vacuumed this morning and I could see some dust on the bottom, so I'm thinking I should keep it going today and do another OCLT tonight.
 
From suggestions in other SLAM threads, I pulled the lights to check for algae and make sure the high FC would get in there. Didn't find any algae but I did find some white crunchy gritty stuff that had no taste at all. Could that be calcium scale? It was like a curved little sheet on the plastic just resting at the bottom of the niche, maybe a 32nd thick (0.5 mm). I also left the brush head, leaf rake and vacuum in the water overnight (friends might call me detail-oriented; anyone else would call me pedantic or the other less flattering adjective!)
 

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Haha, yes, Marian, I was wondering if it might be salt, and guessed that anything in the pool couldn't be all that dangerous. I only tasted a little, lol, and I've had the lights out to change them from the original spooky blue to plain white, so only pool water in behind them. Yeh, Jezza, I was wondering about that - maybe fine sand or even a bit of DE cemented together somehow or a bit of plaster? (it was flaky and didn't sizzle when I poured acid on it).

Day 2 complete except for the OCLT start. I swam in it today just to learn for myself that SLAM level is ok. I learned from another website not to rub my eyes - wow, what a difference I learned from that a couple of months ago. Anyway, no eye rubbing, and I could feel it a bit in my eyes, but only for maybe 30 minutes. From other reading here, I suspect that's more due to the low pH than anything.

Overall a great learning experience!
 
Feels like time to stick a fork in it! FC 23.5 last night and 24 this morning (good advice on testing error :); <0.5 CC and clear as. Now it just needs to get sunny again to burn off all that chlorine, haha.

Thanks Pat, Jezza, Marian and Kim for your support and tips :)
 
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