Difference between dichlor and stabilizer

If I need to raise my CYA level, and the pool needs to be shocked, what is the difference between suing dichlor to shock and add stabilizer vs adding bleach and stabilizer? About a month ago and a half ago, opened pool, because I needed CYA, I used the Walmart brand of dichlor "shock" because it was 11 bucks for 5 lbs. I wasn't able to test the CYA levels at the time (long story, bad pool owner, I know). I was still having a heck of a time keeping the FC level up! (My pool gets a lot of intense sunlight.) I turned off the pump to clean the filter, then the pump wouldn't come back on. Took off motor because impeller was jammed, then had to wait because one of the o rings was broken and had to get replacement part, so the pool was off about a week and a half (yes, I know, I'm a horrible pool owner.) Because it started to turn green, I again used the Walmart brand of shock, which worked wonderfully to turn the pool back to a sparkly blue. I was a bit concerned that I had not tested the CYA levels and could be shooting myself in the foot, and would have to replace some of the water. So I finally got my replacement CYA test tube. I tested the water last night and.....no CYA? I can't imagine I've added this much dichlor since May and it not register at all. Unless algae destroys CYA, in which case I can totally understand it. I'm just wondering, when trying to both shock and raise CYA, is dichlor bad, vs buying stabilizer and bleach?

I know that dichlor will lower pH, but my pH was on the high side. I've also been running the fountain, which will also lower my pH. Also, since I got replacement CH test reagent, I think my calcium levels are a little low? it tested at 200, which for my pool I guess I should have 250? (Gunite is plaster, yes?) Could I buy cal-hypo to use for chlorination until my levels come up, or should I stick with adding the deicer listed in pool school?

In case you ask, because you always ask :) My current readings, from noon today

FC 4
CC .5
TA 80
CH 200
pH 7.2

Thanks :hammer:


LifeTime Supporter
TFP Expert
Jul 30, 2010
Twin Cities, MN
The problem with using dichlor to raise cya is that it raises it slowly. It will go up faster if you use it to shock, but then as you mentioned, you need to watch ph closely.

How much total dichlor have you used? Is it just dichlor or is there other stuff in it? Post it's ingredients.

5 lbs of dichlor would have raised your cya to 17 ppm (using poolcalculator.com and 18000 gallons), so that little would not really show up in the cya test.

concretegardenstx said:
I've also been running the fountain, which will also lower my pH.
I think you just flipped flopped what you meant to say. The fountain will increase ph.