Ready to Start BBB


New member
Jun 21, 2010
I've been a di-chlor/tri-chlor user for 4 years; ready to switch over to BBB. My CYA is 120; my FC is 0. Everything else normal. Soon I will empty 2/3 of the water to get the CYA down, but in the meantine, I want to get the FC up. Water is clear, but I'm seeing some traces of algae. The caculator tells me I need to add 2730 oz of 6% bleach to get my shock FC up to 46.7. I know that's a lot, and I trust the math, but just want to have someone else tell me it sounds right. Also, what's best way to add it? Near a skimmer, or near a feed line? How slow do I need to be putting that much in?
Thanks much.


Well-known member
Jul 8, 2009
Merrimack, NH
When you say you'll be emptying water soon... how soon it that? It seems like a waste of Chlorine if you're only going to be dumping it out soon.

As for putting the bleach in... I normally just pour it near the return.

And I see you got some good advise in another post...



New member
Jun 21, 2010
Thanks, Dan. It might be a couple weeks before I dump it, and have some weekend company coming over.


LifeTime Supporter
Nov 18, 2009
Sacramento, CA
This is the reason you are going to drain, and why you want to drain/refill before you shock. You will spend a fortune trying to shock with your CYA so high.

I am not sure where you got the "46.7" number for FC. Did you extrapolate from the Chlorine/CYA chart?

2730oz of 6% bleach is in the ballpark. I get 2809oz, but I am not sure where the discrepancy comes from.

Again, it will be very difficult to shock with your CYA where it is.


TFP Expert
LifeTime Supporter
Nov 5, 2008
I understand that you want the pool safe to swim in for guests so you want to shock now. But since you are not going to try to keep it as shock level after the guests go, why not just get it into safe swim range and keep it there until the dump and fill? That would be FC 10 to FC 14. Keep the filter running and test often to keep the FC up near 14. You won't kill off the algae but you can probably keep it from going into a full bloom while guests are there.

Otherwise you are looking at STARTING with 15 bottles of bleach, but you may be adding several bottles every hour after that, for several days in a row. We could be talking 30 or 50 or 80 big jugs of bleach at $2.50 or more each.
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