First SLAM (woohoo!)

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pinguy

pinguy

0
May 30, 2015
529
Pennsylvania
Peeled off the cover today to some slightly cloudy water.

YQocDdF.jpg


CH: 325
TA: 110
PH: 8.2+
Salt: 1800
FC: 0
CYA: 40

Added some MA, going to the store to grab bleach and salt shortly.

The pool vac is picking up a lot of clear crystals. Is this salt that has settled over the winter?
 
Salt (NaCl) does not precipitate out of pool water. I would not buy salt if I were you. Your water is likely much too cold for an SWG to run so just manually chlorinate and don't bother adjusting the salt until it is warmer.
 
JoyfulNoise said:
Salt (NaCl) does not precipitate out of pool water. I would not buy salt if I were you. Your water is likely much too cold for an SWG to run so just manually chlorinate and don't bother adjusting the salt until it is warmer.
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I'll wait on the salt then. I was expecting to need to add some due to dilution.

Water temp is about 55 now, what is the lower bound for a SWG?
 
Pentair's cut off at 58-60F. Even so, at low temps below 70F an SWG will not be very efficient. You should check your owners manual but I would just keep the SWG off until your water is consistently above 65F. Manual chlorination will be more than adequate especially at cold water temps since algae is basically dormant at temps below 60F.

Adjust the salt later and measure it with a K-1766 test kit. The SWG salinity readout is not as accurate.

I suspect those clear crystals are probably some kind of carbonate scale, like calcium carbonate. Scoop some up and pour a few drops of muriatic acid on them. If they fizzle and bubble, it's a carbonate.
 
WOW ... just a few hours later and things are already looking significantly better. Still cloudy but I think it will be crystal clear in no time.

U2vx3jl.jpg


I added another 2.5gal of 12.5% Chlorine, and a 3rd gallon of MA (PH still off the chart).
 
Now remember, pH gives a false (high) reading when the FC is over 10, so during a SLAM, don't bother testing pH anymore until the SLAM is over or you allow the FC to drop below 10. Other than that, nice! Stay with it though. Don't slack early just because the water looks better. Maintain until you pass ALL 3 criteria.
 

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Before you do, do this -

Take a water sample and dilute it 1:1 with DISTILLED WATER. Then test your pH. It should give you a fairly accurate read of your pH.
 
pinguy said:
Just tried. The distilled water had a PH of 7.2. A 50/50 mix still showed 8.2.
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Yup. Distilled water has a pH close to 7 and nearly zero TA. When you dilute your high alkalinity pool water with it, it cuts the FC in half but doesn't change the pH because your pool water's alkalinity absorbs the excess hydrogen ions from the distilled water...in other words, your water's TA buffers against a pH change. This way, you can get a more accurate read of you pH at high FC.

So, basically your pH is above 8.2 but that could be temporary from all of the bleach you've been adding. You can keep trying to bring it down or wait until the SLAM is over. Your choice.
 
JoyfulNoise said:
Yup. Distilled water has a pH close to 7 and nearly zero TA. When you dilute your high alkalinity pool water with it, it cuts the FC in half but doesn't change the pH because your pool water's alkalinity absorbs the excess hydrogen ions from the distilled water...in other words, your water's TA buffers against a pH change. This way, you can get a more accurate read of you pH at high FC.

So, basically your pH is above 8.2 but that could be temporary from all of the bleach you've been adding. You can keep trying to bring it down or wait until the SLAM is over. Your choice.
Click to expand...
Thatls a cool trick. I'll wait for the SLAM to be over to avoid the risk of making an acid bath. I don't think it'll be a long SLAM though!
 
Looking completely clear this morning (compare the visibility of the main drains from my last pic). I was in a rush because I overslept so I don't know how accurate my counting was, but I think the FC drop was 1 or less. I forget to test CC in my haste. I'm going to push the SLAM one more night to be sure :D

y2laaYP.jpg
 

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