Killer CYA - Stuck - HELP!

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
11,654
Northern NJ
We can’t tell you if draining is safe for you. You have to decide. We give you the options.

If you have CYA of 160 you can do the 1:1 dilution, get CYA 80 and double it. No reason to go 4X. Really doesn’t matter. Your CYA is so high you need close to a full drain no matter how you measure it.

You are missing that the SLAM Process is not a single dose of chlorine. At your CYA levels your water is unmanageable.
 

texas_scot

Member
Sep 2, 2019
8
Austin, TX
Time to post an update:

Drained around 105% of the pool in 3 batches and got the CYA down to around 45. (BTW my pool seems to be closer to 30K gal than 33K). Even with the dilution, the pool was an ugly green mess, with the first step barely visible.

Started to SLAM on Sat 9/28
By Monday evening, I had added around 15 gal of 10% bleach, pool was still very green
On Tuesday the color changed to an almost phosphorescent blue, and the top step became more visible
8150DB75-CEB5-4EC8-8938-73F9B578F182-COLLAGE.jpg

Since then, added about another 10 gal of bleach, roughly 2 gal in the morning and 2 at night, based off FAS/DPD test results

Here is where we were end of day Wed

27632868-0BEB-4935-8563-746A81AA0C55-COLLAGE.jpg

Definitely making good progress. This morning, we can see all 3 steps and the bottom of the pool at the shallow end.

Had a major panic yesterday when the local Home Depot was sold out of liquid Chlorine and had to use HEB generic bleach (around 6% I think). Was able to order more HDX (24 gal) 10% from the Cedar Park HEB - will pick it up on my way home tonight.

A few questions / concerns:
  1. Filter pressure hasn't risen very much. When I've used clarifier in the past it has risen dramatically inside a couple of days. Is this a cause for concern?
  2. Chlorine PPM. I have only once measured it at the SLAM recommended level of 18. For example, last night I measured it at 10.5ppm around 7:30pm, added 288oz of 6% bleach, and when I measured at 9:30, the FAC was only 11ppm. I then added 384oz of 6% *and* 96oz of 10% which should have taken me well past 18pppm. This morning I was back to 12.5ppm. Does this make sense?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
11,654
Northern NJ
What are the date codes of the bleach you have been buying?

You need to test your FC 30 minutes after adding liquid chlorine and get the FC up to SLAM level if you want it to go as quick as possible.

High FC consumption indicates it is working on the algae.
 

texas_scot

Member
Sep 2, 2019
8
Austin, TX
Bleach date codes are around 19-240 to 19-250. So not very old. Smells very bleachy. Also I did a 10,000 dilution test on the HEB bleach I used yesterday and it came out pretty much at 6ppm.

I can test after 30mins - I waited 2hrs yesterday to make sure that it had circulated.