bgrpph

I'm in Honolulu & I use Trichlor tabs (we have no liquid CL other than household bleach & it's expensive even at costco or wallmart)- My CYA levels obviously rise and i have to drain water regularly- one pool service guy, that has given me good advice in past, told me that the CYA is in the top few feet of the water and it's best to drain water from skimmer to lower CYA & to close bottom drain. He said to either use skimmer to drain to waste or use my elec sump pump & drain from the top part of water. A pool store i buy supplies from said this is nuts, that CYA is evenly distributed and draining from bottom is fine. I've never heard CYA is mainly in top portion of pool. Any truth to this or not?. Thanks folks, great forum- so much good advice !!