Just used my test kit. Should I drain my pool?

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MegaMatt

MegaMatt

New member
Apr 7, 2025
3
Alamogordo, NM
Pool Size
12000
Surface
Plaster
Chlorine
Liquid Chlorine
Hello everyone! I'm a new member who lives in Alamogordo, NM. I just did my first pool test using the TFTestkit. The initial readings indicate I may need to completely drain and refill my pool. But I wanted to come here first and utilize your advice before the added expense of a refill.

I hope I am providing the needed info. I have a 12,000 gallon concrete non-salt pool. with a sand filter. Here are the readings:
  • 6.5 FC, 1 CC, 7.5 TC
  • 100+ CYA
  • 8.2 Ph
  • 280 TA
  • 575 calcium hardness
Lowering CYA apparently requires some level of draining/diluting. The way I understand it, I might need to drain the pool for two reasons:
  1. To lower/reset the CYA
  2. It is generally recommended to refill a pool occasionally (3-5 years?), and the pool has not been refilled in at least the 7 years since I've owned it.
Thanks for your help,
Matt
 
Last edited:
Hey MM and Welcome !!!

90+ is sketchy to read for CYA. Mix up a batch of 50/50 pool and tap. Use that as the 'sample', and proceed with the rest of the test as normal. Double the result and report back.
 
Newdude said:
Hey MM and Welcome !!!

90+ is sketchy to read for CYA. Mix up a batch of 50/50 pool and tap. Use that as the 'sample', and proceed with the rest of the test as normal. Double the result and report back.
Click to expand...
Thanks. This time it was at 40, so doubled my CYA is reading 80. The 50/50 water was much clearer so the black dot on the viewer tube was easier to see. The black dot seems somewhat subjective. I'm going to try one more straight test with just pool water.

EDIT: I tested again with just pool water and it was somewhere between 90 and 100.
 
Last edited:
It can legit go either way here. The doubled result has twice the margin of error and the 90/100 is sketchy. I'd call it 90 and drain/exchange 40% of it. Water has no CYA naturally so it's an even exchange to lower it. 1/3 to lose 1/3, etc. You'll want to drop it to at least 60. Once your insane UV gets going, 30 or 40 won't cut it so no need to go all the way down just to raise it (some) again in a month or two.

But you also want to drain enough the first time because subsequent drains lose new water too.

Have a read to see which way works best for you

Draining - Further Reading

www.troublefreepool.com www.troublefreepool.com
 
A circupool RJ45+ will make 1000 jugs worth of Walmart chlorinating liquid. Even if they boast a little too much, it makes 750+jugs. The question is would you rather lug 750 to 1000 jugs and pay $4620 to $6166, or lug zero jugs for $1300 plus $500 or so to install it ?

Depending on your system and automation needs they all have different outputs and MSRPs, but we can find you one that works similarly in your favor.
 
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