I wouldn't use cat sand at all. The best chicken house bedding to use is pine shavings or straw. I buy bales of straw and it's really quite inexpensive (~$5/bale). You can keep adding to it and as long as there is really good ventilation in the house, the bacterial load stays reasonable, is turned over by the scratching of the chickens, and adds to their immunity. It's GOOD bacteria. You don't have adequate ventilation and/or it's too wet in the chicken house if it starts to smell like ammonia.
What I'm going to suggest probably won't work for the OP, but might for others, particularly those in the south-central part of the country. While my experience is limited, I have had wonderful success so for with rice hulls and food grade diatomaceous earth. Two inches or so of hulls and a light sprinkle of DE in the coop lasts for several weeks. My 5 8-week old pullets love to scratch at the rice hulls, which stirs everything up. Between the dry hulls and the DE I have never "smelled" my coop at all. I clean it out when the poop to hull ratio reaches the point that my wife thinks its too dirty, though I don't think the chickens mind.
The price is right and the results have been very encouraging, so far. I'm trying to find just the right screening material to sift the droppings out of the hulls, which will extend the life of the bedding considerably.