Add ammonia to lower FC?

That isn't a good idea. If you really must lower the FC level use hydrogen peroxide, ascorbic acid, or sodium thiosulfate. In an outdoor pool, lowering chlorine levels is almost never needed, as sunlight will take care of that for you.
 
OK. Didn't realize that Wal-Mart changed their bleach concentration to 8.25. Got the chlorine a little higher than I like, and we are partying tomorrow. I am still below shock level, but not by a whole lot. CYA is 70 and the FC reading I got is 15.5. But since the CYA test is so finicky, I like to stay well below shock level for the CYA level I "get" with my testing.
 
If one mixes concentrated chlorine with concentrated ammonia, then that can produce noxious volatile and irritating gaseous products such as nitrogen trichloride. If you try cleaning up some urine by using bleach, you will get some of this effect. When mixing separately in a pool, this does not occur and instead one initially produces monochloramine that more slowly gets oxidized mostly to nitrogen gas (and some nitrate). As Jason noted, this is not a good way to lower the chlorine level in a pool.
 

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What is this pool store you speak of? :mrgreen:

aasbury said:
OK. Didn't realize that Wal-Mart changed their bleach concentration to 8.25. Got the chlorine a little higher than I like, and we are partying tomorrow. I am still below shock level, but not by a whole lot. CYA is 70 and the FC reading I got is 15.5. But since the CYA test is so finicky, I like to stay well below shock level for the CYA level I "get" with my testing.

If you have a high bather load coming, the FC will come down plenty fast. Besides, you want it on the high side before you start anyways. I'd leave it exactly where it is so you have a clear pool when the party is over.
 
Charlie_R said:
I don't understand -- other than $$ for the pool store -- why that seems to be a recurring theme from the PS.......FC too high? here, buy this. Oops, you used too much, so here, buy this..... ad infinitum.
Most pool stores don't understand the chlorine/CYA relationship so they think that any FC outside the 1-3 ppm range is bad and OMG an FC higher than 5...you must lower it and fast and higher than 10...you'll skin will melt away! :shock: They just aren't well trained and the manufacturers of chlorinated cyanurates (Trichlor and Dichlor) don't want the truth told because otherwise fewer people will use their products. Then the recommend products based on incorrect rules of thumb or on automated programs that don't understand the interactions between the chemicals. It's either ignorance or intentional, but either way it's bad for the consumer.
 
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