gammonlvr_99 said:
I have a 20,000 gallon painted gunite pool. Am new here but have read about bleach use and sounds amazing. So I think I am ready to give it a try. Can anyone tell me how to get started? Test results are as follows
CYA= 137
Total Chlorine = 6
Free Chlorine = 5.7
PH = 7.9
Total Alkalinity = 121
Adjusted Alkalinity = 80
Total hardness = 365
thanks for any advice you can offer also if I use the bleach do I need to dilute and what is the follow up using bleach?
BBB is easy, once you get your water chemistry straightened out, which is the first thing you need to work on. First, read this
sticky which is the ABC's of pool chemistry. This gives you the recommended ranges you need, and will help you understand why I'm suggesting what I am below.
(1) Your CYA is way too high. Ideally you want it around 30-40 if not using a SWCG. With your CYA so high, you need a bunch of chlorine just to maintain sanitizing levels. Unfortunately, the only way to lower CYA is to remove water. I think the general consensus is you can lower your water 18" below your skimmer, and then refill, test, and then repeat. With your CYA that high, you're going to have to do this step several times.. sorry
(2) Your pH is borderline high, probably because your TA is borderline high as well. Use Jason's pool calculator
here to determine how much muriatic acid to add to lower your pH to around 7.4 - 7.6 . To lower your TA, add enough acid to bring your pH down to around 7.2, then aerate your water using a return jet or a spa, waterfall, whatever you have. check your pH and TA the next morning, and repeat until your TA is around 100 or so. Check your pH, and either add borax to raise it if needed, or acid to lower it if needed. When adding acid, add it slowly in front of a return, or walk around your pool and drizzle it in the water - do not just dump it in (this applies for bleach, too).
(3) You're underchlorinating your pool right now (see #1 as to why). Using Jason's pool calculator, for CYA=137, your FC should be between 11 and 17 to maintain the proper sanitization of the pool. I'd get my CYA down as quick as I could. For example, for your size pool, to reach FC=14, you would need to add 3.5 jugs of 6% bleach to get to 14. If your CYA was 40, then your FC needed for sanitation would be between 3 and 7, and you would be there already, and it would take a cup or two every evening to maintain this level.
So, to recap, get your CYA down by doing partial drains and refilling, get your pH and TA down by adding acid and aerating, and then you should be good to go!
To answer your question about bleach, there's no need to dilute it, just know what strength you're using (6% or 12%), use Jason's pool calc to figure out how much you need to add, and add it slowly in front of a return. Plain old generic bleach is best; no scented or other ingredients other than sodium hypochlorite.
