First SLAM

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jeqwerty1969

jeqwerty1969

Gold Supporter
May 3, 2020
36
Inglewood, CA
I just got my new filter cartridges and plumbing tip-top so I'm about to SLAM the tap water refill (I drained it dry). FYI I added 2 gallons of 10% chlorine and 10 crushed pucks a few days ago to hold me over while waiting on filter parts. This (with the solar cover on) gave me the FC and CYA levels I'm able to start with.

5 PM:

FC 15.5
pH 7.6
TA 57 (250ml method since I'm still unsure of volume)
CH 250-400 (transition to purple vs. solid royal blue)
CYA 60
Salt 572

I have three questions as I begin though...

1) I was going to add my salt 80 lbs at a time to use my digital meter and try to hone my gallon estimation. Will this throw off any of the SLAM process or can it be done in parallel?

2) My CYA testing confidence is still zilch. In a certain light I filled the tube no problem and in another I got 40-60. People say "back to the sun" but also "lots of light in the side" which directly conflicts. I'm going to make a 50 ppm sample with distilled water to try and see if I'm in the ballpark but I don't know if I should postpone my whole SLAM for a lab sample in the mail?

3) Calcium seems high since I'm on LA water and I filled fresh just recently... I expected a little lower. It's another of the reagent tests which is not dummy-proof out of the box. They say "turns blue" but there are 6 drops between the most rapid transition from red to "purply" and where I would confidently say "blue" with no trace of red. Where is the best place to stop?

Thanks all!
 
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1) Keep the SWG off during the slam and slam as if it were a non-SWG pool, but you can add salt if you want. Maybe go a bit low because the liquid chlorine will add some salt - you can fine tune the additions when done.

2) You want it to be bright but not direct light.If it’s too dark then there’s not enough indirect light to make the tiny particles of CYA with binder obscure the dot but direct light can make it show too well too. So that’s why full sunlight, back to the sun, don’t cover the sides with your fingers is the typical advice.

3) The test is done when the color stops changing at all. Keep adding drops until the last drop doesn’t change the color, then subtract that last drop.
 
Thank you, thorough and clear as i could ask for. I have a 50ppm CYA sample in the mail and I'm thinking about making a light box since sunny days are 50/50 here. My gut tells me I'm looking at 30-40 CYA results but I need to be sure at least which side of the reference I'm at.

Last night I added the salt and chlorine and in error a 4 lbs box of baking soda for volume calc (i brain farted... as I've been warned that high chlorine makes the TA test orange so I cant compare with any accuracy).

10 PM (3 hours circulation):

FC 24
pH 8.4? (inaccurate during slam but may need acid for my soda mistake)
TA 120? (never goes red)
CH 350
CYA 35-60?
Salt 1466 (based on digital readings I'm fairly confident that it's closer to 11,000 gallons)

8 AM:

FC 17.75
pH 8.4?
TA 120?
CH 350
CYA 35-60?
Salt 1463

I think I should add a jug of muriatic just to course correct the pH in the blind, but as far as the slam I cant know until I'm confident on CYA level. Last night I got .5 CC but this morning there are no combined chloramines, so I might be good as soon as I pass the FC test overnight.
 
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If you're really worried about the pH and TA you can let the FC go down to around 10ppm and test it. Adjust it, get back into the SLAM. The TA test will still work, but the colors will be different - the color shift is what you are looking for. But you really only need to typically worry about TA when you're adjusting the pH, to know how much acid to add to adjust the pH.
 
aI dont care personally. If it doesnt affect the SLAM I'll just wait til FC is dropping naturally to worry about the rest.

Also, the sun came out and I did the CYA a couple of times. I think the trouble is compounded by a psychosomatic affect or "visual memory" if that makes sense, and keeping both eyes open seems to also create an issue. I have slight cataracts and moderate prescription glasses as well.

At 35-30 I feel like "this is what the average person would call obscured" but I can still "perceive the dot". At 25 my gut says I'm close, but it's not completely monochromatic until 20-15.

For SLAM purposes would you over estimate or under estimate?
 
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It's best to start with the pH at 7.2 for a few reasons - the main one being the liquid chlorine is pH neutral when it's added to the pool, so the CO2 offgassing naturally occurring will only cause the pH to rise. Also, the chlorine will work better when the pH is at lower levels. But baking soda mostly affects the TA and not the pH - just checked pool math and 4 lbs of baking soda even in a 10k pool only increases pH by 0.06, so I wouldn't worry about it. :) You can still do your volume calc, though, you just have to watch for a different color shift in the TA.
 
The pucks (you said 10) would have raised your CYA by around 30 ppm (your volume is 10-13K). If you drained the pool dry, that is what your CYA level in the pool water is.
 
I finally passed the overnight test. I had the waterfalls off and I think that drew out my SLAM since they have small pools that really need to remain in circulation. Lesson learned.

Screenshot_20200525-111300.jpg

CYA test remains frustrating, but using the calc as a reference, I think I've got it down as well as one could hope for. As soon as my reference solution comes in I'll make a comparison and post some images for other new folks.
 

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Round the CYA test to a whole number of 10 -- so in your test log it would 40 ppm.

Good job.
 
Thank you! Based on 10 pucks I bet it's around 30. I have 40 oz by volume CYA in the sock now and I expect to cruise up to a 60 ppm plateau while I maintain it as a liquid chlorine pool. When I manage to get the SWCG replaced i should already be close to optimal. My salt meter readings continue to cast doubt on the volume estimation, but my overall average sounds correct based on the city water meter during fill week

Salt 1 +Lbs Salt 2 Vol. Est.
572 80 1463 10,766
1463 80 2240 12,345
2240 80 3135 10,718
3135 80 3816 14,086

overall
(320 * 1000000) / (3816 - 572) / 8.34 = 11,828 gallons

I definitely goofed and added a bag too many, but I may be fine. Rain happens.
 
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