You have to be careful completely draining a pool so it doesn't pop out of the ground like a big boat. I'm assuming in Arizona the water table is extremely low so this probably is not an issue for you but wanted to throw it out there just in case.

I wouldn't use any type of sudsing detergent to clean the walls with. Any leftover residue and you'll have a pool full of bubbles! You can scrub it with baking soda.

When you do refill it, you can use our Super Simple Start-up Recipe which is ideal for a freshly filled pools. You can read about it here:> http://pool9.net/ssr/

You also need a good test kit. Test strips are pretty worthless. The kit we like is the Taylor K2006 or 2006C (better buy) that you can get through this link as it is very doubtful that you'll find it anywhere locally:> http://pool9.net/tk/

By the way, the reason your CYA got so high was from the trichlor tabs. Using the dichlor in the start-up recipe will add the needed CYA as well as chlorine so don't use any more tabs. When your CYA gets to around 50 or so, discontinue the dichlor and then go with just bleach.

If you don't want to use the recipe, you can just use bleach from the get-go but you'll have to add some CYA separately. If this is the route you would rather take, let us know and we'll figure out how much CYA you need to add.

This link has a chart that explains the connection between CYA and chlorine:> http://pool9.net/cl-cya/

Hope this helps. Let us know if you have further questions and someone here will be glad to help.