New to TFP - Opening Pool Soon


New member
Apr 14, 2018
Faifield, IL
I just found TFP a few weeks ago and have been devouring all of the education on the site. Needless to say, last year was a complete disaster following what the pool place told me (lots of pucks in the chlorinator and bags of shock,) which led me to believe my CYA will probably be high when opening the pool this year. I got the TF-100 kit and was able to reach through the skimmer and get some water in order to do a CYA test. The pool is still closed with cover on. My test came back 100 ppm, which didn't surprise me.

My question is: should I go ahead and open the pool, add water and do another CYA test then drain based on results, or knowing I need to drain the pool half way, go ahead and siphon it down to half full?

My pool is 17,200 gallons above ground vinyl liner. I would say it only needs about 3,000 gallons added when I open.


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
Welcome! :wave:

I suggest you repeat the CYA test using the dilution method. What you read as 100 could very well be 120 or even 150 -- the graduations get real close together at that end of the view tube. Dilution method is Step 8, here.

Then drain accordingly. There's no point in adding water only to dump it out in a day or two, nor is there any good reason to start treating the water only to dump it, either.

Once you've drained off what you think is enough, refill, let it mix, and then retest everything. If anything, drain more than you think is necessary; it's easy enough to add more CYA -- you probably have a good supply of trichlor pucks left from last year! Since it's a new kit, pay attention to the note about static electricity here.

If the next step doesn't seem obvious, post up the results again and someone will be along to advise you.