A week passed with no ammonia so we got more raw shrimp and put them in a baggie with gravel and punched holes, same thing. We've been testing the water almost everyday now and the ammonia is still almost NIL and the goldfish in there are thriving.

Someone on here recommended putting raw shrimp in the aquarium and said we would only need three large ones to cycle it in 10 days or so...there's about eight large ones in those baggies. What the heck is going on?
The tank's primary filter is a homemade wet-dry with a 30 gallon sump and natural sponge as the biomedia. It has built-in glass overflows. We have not been changing the water at all, just adding water as it evaporates. How can we get this thing to cycle?