You are probably using so much chlorine because you have no CYA in the water or are still fighting something organic in the pool. Without CYA, it is nearly impossible to keep chlorine in the pool. You can either add some CYA directly as a separate product or use some dichlor which adds chlorine and CYA at the same time. Most pools do well with a CYA level around 50. (If you buy some separately to add, it might be called stabilizer or conditioner. Ingredients should say cyanuric or isocyanuric acid.)

If brown water is shooting through your returns, you have one of three things going on or a combination of them:
1. Your pump is too powerful and is simply forcing debris through the sand bed back into the pool. (Common problem.)
2. You do not have 'pool sand' in your filter.
3. Your filter is malfunctioning. You can test this by throwing a handful of DE in your skimmer and watch the return. If you see white powder shooting out, you know you have a filter problem.

What kit are you using to test with? Can you give us some current water testing results taken with a drops-based kit? What all have you added to the pool -- meaning ingredients and not product names.