Decreasing CYA Levels Without Draining or Water Exchange. WHAT?


Bronze Supporter
Apr 27, 2018
Midland, MI
I was walking around a pool store for some last minute LC (since Walmart is out of stock) and saw something unusual. It was a package that showed how to decrease your cya without draining or water exchange. The pool store tried to convince me that it works, but I wasn’t having it. I just got my liquid chlorine and left. Ugh 🤦🏽‍♀️

How is the below pic even possible? A load of nonsense is what I say imo. Ugh.

Rattus Suffocatus

Silver Supporter
Jun 5, 2019
Corona de Tucson, AZ
Look at the reviews on Amazon. Doesn't work. And by the way, Walmart sucks... they apparently only have Christmas stuff in September (Looking for New Years or Valentine's day now that it is October) even only in places that you don't ever close a pool... Their LC isn't available anywhere, even when searching on the internet. Have to run to a pool store now.... I just added my first 1/3 of a gallon this morning.. so yeah, it would have been nice as a backup source... I'll end up using about a 1/2 gallon a day if I calculated correctly... I still have a little of the initial Trichlor from startup left... Once it's gone, it's gone.

As for the CYA reducer, Even here in AZ, if I did a 1/3 way drain it wold be cheaper than that stuff....even if it worked...
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TFP Expert
LifeTime Supporter
In The Industry
Jun 12, 2009
NW Ohio
Do a search for BioActive. It's been around for a couple years now.

The theory is good. Some bacteria does consume CYA and converts it to ammonia, this happens occasionally over the winter. If the ammonia is left it takes huge amounts of chlorine to remove. Sometimes the process continues and the ammonia is then reduced to nitrite and further to nitrate. That all said, attempting to package and control this has had very little success. When long-time members of the site attempt to do it with careful measuring and record keeping it almost exclusively fails. Most successes are reported by new members using unreliable testing to tout their results. Which is unfortunately par for the course in pool chemicals: it isn't important that it works as long as the user thinks it worked.

So not total nonsense, but water exchange is 100% effective 100% of the time. This stuff, well, 5% of the time it works every time :laughblue:
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LifeTime Supporter
Aug 19, 2014
Pacific NW
As someone who tried BioActive in mid 2015: Additionally, you will probably have to slam after as it requires
such low FC to not disturb the living organisms that consume the cya.

I ended up with my first Algae outbreak after trying that experiment and right when the house
was going on the market. Thankfully the slam was finished a few days before the open house,
but what a pain in the rump that was!
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