That makes sense, it's hard to calculate how much Cl to add when you don't know the strength. I found a great website today, all you will probably want to know about Cl & then some:
[ DELETED BY ADMIN -- SEE EXPLANATION BELOW ]
They explain that Liquid Cl "LC" from the manufacturer is 15%, but in two weeks it's strength is 12.5%, & in 30 days down to 9% strength. So if it was from the spring it's probably no stronger than the recently stocked Walmart 6% bleach. The good news from dumping all this liquid Cl in my pool is it has effectively lowered my CYA. It is now reading 78 
I'm guessing because of the high Cl demand from the algae, the CYA is bonding with all the liquid Cl I have been adding, which is being consumed by the algae? Still not cleared up, but making slow progress.
Another interesting point made in the article:
[ Mis-information deleted ]
Last edited by PoolDoc; 08-01-2012 at 10:39 PM.
Reason: merge sequential posts
16x40 IG fiberglass pool; 20K gal?; automatic cover; sand filter; solar heat; 24hr pump; Lamotte ColorQ7; PF:6 net-dev
16'x40' rectangle 16K gal IG pool; trichlor feeder; ? sand filter; ? pump; 24hrs; Lamotte Color Q 7 digital liquid test kit; well; summer: ; winter: ; android phone; PF:7.5
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