+ 1:1 dilution for CYA testing means, take your water sample and mix it 50:50 with tap water, and than test that mixture for CYA. (So, you end up with 1/4 pool water in your mix bottle.)
+ Trichlor tablets; dichlor is a fast dissolving granular material
+ Low on CYA? Use trichlor exclusively to chlorinate till they are used up. Only use bleach to boost chlorine levels if they get too low. (Do NOT pour bleach on top of tablets!!!)
+ Add borax as needed to maintain pH. (You can add borax on top of trichlor -- one of the very few chemicals you can do that with!)
+ A 30' round 48" pool holds about 18,500; a 52" holds about 21K. I put that in your signature.