Reopening the Pool this weekend for the first time

matasoj

Gold Supporter
Jul 1, 2020
16
Conesus, NY
Pool Size
16900
Surface
Vinyl
Chlorine
Liquid Chlorine
Hey Guys -
Last year, I started with whatever junk the pool store gave me (including the person dumping a LOT of stabilizer into the pool the very first day). It took me a couple weeks to find this site, and although the water has been perfectly clear all last summer, and even over the winter (I just pulled the winter cover and it's still wonderfully clear), The numbers seem high and to avoid problems I think I will need to do a drain/refill process a couple times to get things back on track.

Here's the pool when I pulled the winter cover off (the pillows lasted all winter, just deflating as spring came around, so that's good) a week ago (replaced with the solar cover):
IMG_6950.jpg
And here is my new pool robot sweeping up the sand and remaining leaves yesterday:
IMG_6998.jpg

So it is looking good, but some of the numbers like CYA are still out of whack, so I am looking for opinions. When I closed the pool late last Oct, the numbers were as follows:
FC: 25.0
PH: 7.6
TA: 210
CH: 230
CYA: 115 (or 120 or so - it was so high it was hard to get a good reading)
Temp: 55ºF

So I tested the water 2 days ago, and the tests came out as this:
FC: 9.4
PH: 7.3
TA: 210
CH: 240
CYA: 100+ (somewhere between 100-110)
Temp: 57.9ºF

So I am thinking that with the CYA as high as it is, and this pool being a 54" Vinyl lined pool, that I should drain the water 2/3 of the way (down to about 18" of water or so) and refill, then re-test and apply bleach/soda ash/muriatic acid as needed to bring the numbers back in line.

I thought I would ask here if the opinion of more experienced people in the pool game concur, or if there is something else I should do?

Thank you for such a great resource!
Jim
 

CTFocusST

Well-known member
Jul 4, 2019
174
Glastonbury CT
Pool Size
13500
Surface
Vinyl
Chlorine
Liquid Chlorine
You are on the right track. I would start with a diluted cya test (step 8 in link below) first to give you a better idea of how much water you need to exchange. Cya test isn't accurate above 100 and you could be much higher than 110

 
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matasoj

Gold Supporter
Jul 1, 2020
16
Conesus, NY
Pool Size
16900
Surface
Vinyl
Chlorine
Liquid Chlorine
OK, so I finally had time to do the X2 CYA test, and it came out at 100. What is the formula for figuring out how much water I need to let out of the pool? I was planning on just dropping the level to about 18" and re-filling, but if there is a formula I can follow to be more exact I would prefer that. The pool is a 27' pool that has 54" walls, which if memory serves had about 48" of water in it last year.
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
10,491
NY
It’s an even percentage no matter what the CYA level is. Fill water has 0 so a 1/3 drain would remove 1/3. It’s even easier being 100. Want a CYA of 40 ? Drain 60%. 30 would be 70 and so on.
 

matasoj

Gold Supporter
Jul 1, 2020
16
Conesus, NY
Pool Size
16900
Surface
Vinyl
Chlorine
Liquid Chlorine
I drained the water down to 19" deep and have mostly refilled it. I have about 12" more to fill, but it looks like I need to replace the skimmer gasket due to the rust stain running down from it. Considering that the pool is less than a year old, seeing rust seems like a bad thing. But I am hopeful that the gaskets will solve the issue.

rustStainsFromSkimmer.jpg

Anyways, I ran a quick test, even though it wasn't full, just to get a feeling for where the stats are at now, and here's where I stand:
FC: 2.6
PH: 6.8 (that's a guess, as the gauge doesn't go below 7, but it was pee yellow)
TA: 140
CH: 160
CYA: 50
CSI: -1.09
TEMP: 52.4º F

I added the recommended 95oz of 7.5% bleach per the app recommendation, and added 6lbs of Sodium Carbonate to get the PH up into a hopefully measurable range (app recommended 9lbs, but I didn't want to overdue it on a guess)

I'll test again tomorrow and see where we are at, but I'm pretty happy with the CYA dropping so much. Is the TA something I need to worry about? Last summer the TA ranged from 130-170 throughout the summer, and the PH seemed fairly stable. This is only my second summer doing this, so I'm curious what other thoughts are...
 
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CraigChing

Gold Supporter
Jun 15, 2019
188
Plymouth, Minnesota
Pool Size
22000
Surface
Vinyl
Chlorine
Liquid Chlorine
Your TA appears to be lower now than it was before. I wouldn’t worry about TA too much, your pH will rise and you’ll then use muriatic acid to lower both pH and TA (enough to lower pH to 7.2). For now, I’d probably aerate a bit to get the pH up, you want your pH in the 7s. You can choose to keep aerating to 8 and then lower it with muriatic acid, or let it rise on its own and then use muriatic acid to lower it. It will take awhile, but the point is to find the TA level where your pH stabilizes.

You should also test your fill water so you have an idea how to explain differences in your measurements after a fill.

Congrats on your CYA! I’ve been fighting mine for a couple of years now, but maybe next year it will finally be normal! I would do a drain like you did, but I’ve been fine managing it and haven’t had any problems yet. I have super high TA fill water, so I don’t want to drain until I absolutely need to. If I need to SLAM, I will probably have to drain at that point.
 
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matasoj

Gold Supporter
Jul 1, 2020
16
Conesus, NY
Pool Size
16900
Surface
Vinyl
Chlorine
Liquid Chlorine
Does Soda Ash raise both TA and pH? I added some to try to get my pH up, and my TA jumped too.
 
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