It looks like I have a problem. I have tested the tap water, ammo, no2, no3 all 0. The ammonia is plain ammonia, no other ingredients listed and it passes the shake test.
I put the filter media in a large bowl of tank water and changed the water all the way down to the gravel. I used warm water and API Tapwater Conditioner at a rate of 2 drops per gallon. The instructions call for 1 drop/2 gallons for chlorine or 6 drops/gallon for chloramine. I called the water treatment plant to confirm the use of chloramine or chlorine. Only chlorine is used, no chloramine.
I did the water change early Friday afternoon. This morning ammo is at 4ppm, no2 is 0 no3 is 0. I assume that after nearly 3 days, there should have been some change if the colony were still alive.
Today I plan on emptying the tank, cleaning everything in de-chlorinated water and using new filter media and a different de-chlorinator. I bought a new chlorine test kit for swimming pools, but the water in the tank shows no trace of chlorine.
Whatever went wrong, it must have happened around 4/24 (day 12). That seems to be the day that everything stopped. On 4/20 (day 8) ammo was 4, no2 0, no3 0. On day 9 ammo 4, no2 .25. Day 10 ammo 4, no2 1.0. Day 11 ammo 4 no2 2.0. That's where everything stopped. The readings never changed again until 5/2 (day 20) when I did the 20% pwc.
It's very odd. Everything was moving right along, as expected, then just came to a halt. I have a sneaky suspicion that something was added to the tank without my knowledge. We had a lot of people over on 4/23 for my birthday party. I can't help but wonder if some fool dumped a shot of bourbon or half a beer into my tank. The timeline fits and I was outside most of the day.