ARe you testing the RO water before or after prime? Prime will give a false positive on ammonia test after dosing. With a good RO unit, you shouldn't need prime if there is nothing else in the water.
20g platy, , 2 x 10g shrimp, 3 x 20g shrimp, 7.5g shrimp and 1 great dane/mastiff puppy.
Sump Pimp #2
My Tanks and my shrimps