How many shrimp in the tank? What is your nitrate? IMO your feeding alot of food over the course of the week. I feed my 10 gallon tank with 50 CRS and 10 snowballs twice a week. So far so good and I got snowball babies.
Edit, nitrate 0 is kinda odd.
You are assuming I feed large amounts. Any food I feed is gone within 1-2 hours, this includes fresh veggies. I feed TINY amounts on the days listed.