I just recently picked up a Seachem Free Ammonia tester to monitor my ammonia levels. I test with API and always have a reading of 0 - 0.25 ppm total ammonia, but the seachem reader is reporting 0.05 ppm free ammonia or the "alert" level. I just did a 100% water change last night and double dosed my tank with Prime. My tap water has an ammonia reading of 2.0 ppm. The tank is fully cycled and had been running for a month with 0 nitrite and 20 nitrate. I know the prime binds ammonia into the less toxic form for 24 hours, so should I continue to dose the tank daily until the sensor reads zero. Is it possible to over dose with prime? The directions say that you can use 5 times the dose in an emergency, but I don't want to stress them by adding it every day. It is a 40 gal breeder with three fantails, about and inch long each. I vacuum the bottom twice a week (this usually drains 10 to 15 gal and I treat the replacement water at double dose too). There is a Ex70 filter with regular charcoal media and an Ex20 filter full of ceramic bio-media and a mechanical fine mesh filter sponge thing.