Replacing water...confuzzled!

CSI is dominated by pH, TA, and CH. It is effected by water temperature, CYA, Salt, and Borates.

So in essence, your CH is pretty stable. The CYA and salt are too. You have no Borates. And you can monitor the water temperature. Thus, pH is the primary value to change CSI, along with TA as it changes (lowers) when you add acid and (rises ) if you add high TA fill water.
 
Ok, my pH today is up to 8.0 (first time I've checked it since SLAM) and FC is down to 4.0 (sunshine!) which is in the normal range but I need to boost it up while I work on the BA. (Logs are shared.)

If I understand correctly, keeping the FC high also tends to raise the pH, so that's why we aren't supposed to fuss with pH during a SLAM. But now that the SLAM is over, I'm still going to maintain higher-than-normal FC for a while.

Can I get the pH low enough to address the CSI problem while also keeping my FC up? (and maybe I'm asking the wrong question?)
 
The SLAM does not raise the pH. pH is hard to measure with FC over 10ppm. That is why we tell you not to bother. Now that you FC is 4 your pH reading is correct.

Also since you are trying to get rid of scale we will need to lower your TA as well. Lower your pH to 7 with MA. With a TA of 180 it will rise pretty quickly, however, that will help lower your TA. You will need to repeat that process a few times to get your TA under 100 where is will need to be.

You are doing great, keep it up and keep asking questions.

Now stop typing and go scrape at that BA
 
OK more questions! I learned my colors from Crayola, so I need a lesson in pool chemistry color matching... I am not sure I'm getting my TA and CH right because I'm confused about the colors.

1) On the TA test, the water is supposed to change from blue to red. Is this red? I would probably call it "magenta", but it doesn't seem to get any more "red" than this. In the photo, I am using the pH indicator for comparison, because that seems a little closer to "red" (ish) to me.

IMG_20210616_121356.jpeg

2) On the CH test, the water is supposed to change to blue. It turns bright purple, then eventually gets to a light shade of purple which I would call "periwinkle". To me, this is not "blue" exactly...but is it the blue we are looking for here, or do I keep going?

IMG_20210616_121550.jpeg

🌻So Grateful🌻 for all the help!!
 
Being male, I do not see the fancy colors. Your TA test looks red to me. The CH test goes from a purple to blue on my test. There is a color change. The background can effect the color you see. Be sure to have a white background.
 
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Ok....I added about 1# of dry CYA this weekend. In the 24 hours I waited before retesting, I added some water to replace a couple of inches lost to evaporation since the initial fill. Today my CYA levels are DOWN from where they were last time I tested. We're actually below 30 now (I can still see the black dot when I fill it to the top). I thought CYA didn't go down on its own? Could the added water make that much of a difference? I probably blew it by not testing right before the CYA addition and by adding water!
 
The CYA test is very dependent on consistent lighting conditions. It uses the turbidity of the water to show you your CYA level. If your sample is in direct sunlight on a bright day the sample will appear more opaque and the dot will be less visible. That same sample on an overcast cloudy day, or in the shade, will appear less opaque and you will be able to see the dot much better.
 
I added about 1# of dry CYA this weekend.
Also, adding 1# of stabilizer in your 22,000 gallon pool will only raise your CYA level about 5ppm. That's probably not enough of an increase to even see a difference on the CYA test, especially at lower levels.
 
especially at lower levels.
Good to know. I chose 1# based on PoolMath's recommendation to get me from 30 to 40, but I guess if it was a bit lower than 30 + water added + what you said here, then it starts to make more sense.

Question: @cowboycasey said I might have lost 3ppm over a few days. I need to understand what causes loss, since I had the impression it pretty much never went away on its own. Thanks!
 
I need to understand what causes loss, since I had the impression it pretty much never went away on its own. Thanks!
Water loss through backwashing, vacuum to waste, a leak, splashing water out of pool.

Example, in an 18'x36' rectangular pool, lowering the water level by 6 inches by backwashing will drain out 2400 gallons of water. That could easily drop your CYA by 3 or 4 ppm.
I'm not saying that you drop your water 6 inches with a backwash, but think about 6 to 10 backwashes, they add up.
 
it does add up, most pools lose 3 to 6 CYA a month "or so" You have a cart filter so no backwash but you will have splash out and water loss other ways.. And CYA does go away slowly, it does not go away fast like sometimes we want :)
 
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