Converting another neighbor to BBB.....


LifeTime Supporter
May 14, 2012
Gulfport, MS
I am swapping another neighbor to the BBB :-D ...However he has somewhat clear water and green alge sitting on the bottom and floating in the water. As I have never had to fight alge before I am looking for some advice to help him out. His current water shows no FC and his CYA is 70. Going by the CYA/FC chart his shock level should be at 28 :shock: So I told him to go buy 30 gallons of 12% liquid chlorine and we are going to start fighing it Saturday morning. His pool is a 27' round AG 54" deep with a sanddollar 60 filter system. So I have a couple questions:

--When I get the water to the 28 shock level at what level should it get to before I bring it back up to 28?

--Do we need to vacuum out the alge before we start?

--Does the pump run 24/7 till the alge is dead?

Thanks in advance.


TFP Expert
LifeTime Supporter
Aug 30, 2010
Dallas, TX
Keep it above 28
Anything you can get out ahead of time is beneficial.
Run the pump 24/7 to help clear the pool. It's going to turn milky once you start.

Bama Rambler

Mod Squad
TFP Expert
Bronze Supporter
LifeTime Supporter
Jun 22, 2009
SouthWest Alabama
Shawdaddy1972 said:
--When I get the water to the 28 shock level at what level should it get to before I bring it back up to 28? Test in an hour and bring it back to 28 from wherever it is.

--Do we need to vacuum out the alge before we start? You don't need to, but you can start if you want.

--Does the pump run 24/7 till the alge is dead? Yes, and the pool is clear.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
Houston, Texas
I would vacuum out the algae first, moving very,very slowly to disturb it as little as possible. Once it is all stirred up your neighbor will have that pea-green mess you hear about so often. I would also recommend draining and replacing about 1/3 of the water volume to get the CYA down to a more reasonable level before beginning the shock process.

When completing the shock process, the rule for the first couple of days is to bring the pool to shock level and keep it there as much as possible. That means you will be testing and adding chlorine every 1-2 hours. Keep the pump running 24/7 until the process is completed and back wash the filter whenever there is a 25% rise over the normal clean pressure reading. You may be back washing frequently the first couple of days as well.


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
I'd vacuum out as much algae as possible before I started. It means less work for the bleach. And if you can vacuum to waste and lose some of that CYA-laden water, even better.

If shock level is 28, that means you want to keep it above that. Although that level may change if you replace some water. It's based on the CYA level, as you know. So, let's say 28 is the level. Round up a little when pouring the bleach in. If it wants 6.5 gallons, just dump in 7. In an hour or so, recheck, and get it back to 28 or above. Keep brushing, keep filtering, keep replenishing the bleach. The more consistently the level is kept at 28, the faster it will go. But chlorine loss is related to concentration, so don't go overboard and run it up to 50 - it will bleach the liner and waste bleach. Each time you recalculate, you should be needing less and less bleach to get it to 28. Watch the flow and the pressure gauge and backwash when needed.

How to Shock Your Pool goes into more depth.

Tell him to stock up on liquid for the pool boy, too.