Draining pool today, am I doing the right thing?

creede

Member
Jun 22, 2017
5
Austin, TX
Hi TFP team. As with many people I come here hat in hand having been a poor pool owner for the last 3 years. I actually found this forum when I first got the pool, and found it to be incredibly helpful. Sadly I didn't take the time to really learn the TFP way. Because of that I've been using tabs to chlorinate my pool for the last 3 years. Last season I did notice that my chlorine levels needed to be quite high to be effective (greater than 5) but my local pool store didn't seem stressed so I kept going. This spring my chlorine levels were off the charts (great than 10 on my little taylor kit) and I finally decided to get serious. I ordered a test kit (Taylor K-2006 from Amazon) and found that my CYA levels were off the charts. I had to dilute 4 times to get a reading of 100, so I'm assuming I need to drain 3/4 of my pool water. On top of that I had recently had some issues with my PH which resulted in a high TA, and perhaps because of that a high CH.

The numbers:


CYA: 400
CH: 900
PH: 7.2
TA: 200

We're expecting a week of raining weather here in Austin, so I figured now was as good a time as any to drain the pool. I intend to convert to SWG this summer so I figure about 3/4 of the water needs to go. It's currently raining, and I'm currently pumping out as quick as I can. Any advice or encouragement appreciated.

Side note, during this whole COVID thing, what's the easiest way to buy liquid chlorine? Amazon? Any recommendations?

Thanks!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,786
Laughlin, NV
Welcome to the forum!
I assume you know of the risks of draining a pool. Get it done quick and refill. I would suggest you drain most of it. With those types of test results, best to start pretty fresh.
Best place for liquid chlorine is Home Depot, Walmart, Lowes, etc.

I suggest you read ABC's of Pool Water Chemistry.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
18,149
Northern NJ
Welcome to TFP.

Get your CYA done to the 50-60 range if you don't plan on putting in a SWG now. That is a 85% drain.

What is your pH, TA, CH of the fill water you will be using?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,786
Laughlin, NV
How did you get 900 ppm CH in your pool water with that fill water?! I wonder if your fill water changes in composition during the year.
 

creede

Member
Jun 22, 2017
5
Austin, TX
OK, I managed to get it mostly drained and refilled in the last 24 hours. The bad news is only after doing so did I realize I was doing the CYA wrong. I had a value over 100 and so I was diluting by half with pool water and rechecking. I realized my error after it was filled this morning. Doing it the correct way post refill I got a CYA of 100. Crazy to think it must have been 500+ before the draining. I did take a sample to the pool store to double check and they gave a CYA of 90.

Current readings are:

PH 7.6
TA 70
CH 290
CYA 90

Phosphates 300.

I also subscribed to the pro version of the pool math app. Super handy, thanks to whoever spearheaded that. I also have 8 lbs of Calcium Chloride on the way to get my CH up.

I also picked up 4 gallons of blue whale brand liquid shock from Leslies. I've been fooled by them before so I wanted to double check that this was the correct liquid chlorine to use.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,786
Laughlin, NV
You do not need the calcium chloride. Cancel that order if possible.

Look at the bottles. Should say 10% or 12.5% sodium hypochlorite.