[fish_4_all]

The actual problem could be the test strips. I used to use them and had the same problem. Low results for nitrates and nitrites and ammonia would fluctuate with tests not 30 minutes apart.

I personally would recommend the liquid regent tests from either Aquarium Pharmaceuticals or another descent manufacturer. I think Redfin is recommended for nitrates and another company for phosphates but I don't remember which one.

Something else that might help is to treat the water before adding it. Also, not feeding the fish for 3 days could have caused a drop in waste from the fish and over a couple days the concentration, not quantity, of their waste caused a spike in ammonia. Have patience and keep up with the water changes.

Make sure you biowheel is always wet and turning, as I a am sure you already know, and that you are rinsing the filter media in tank water and ot tap water otherwise you are killing the beneficial bacteria.

Best of luck, keep asking quesitons and try to be patient with it. Sooner or later you will have your tank up and running.

 

[fish_4_all]

Something has to be killing your bacteria, either that or your test kit is bad. Take a sample to your LFS and have them test it. If it comes back with nitrites or nitrates, your test kit is bad.

When you do a water change, are you using tap water and a clean bucket or one that might have been used to wash a car or had some kind of detergent in it? If so, the soap could have killed your bacteria and wouldn't know how long it will take for the detergents to stop affecting the bacteria.

There is still the possibility that it is simply going to take a long time to cycle. I have heard of cases where it took 3 months so 18 days is nothing comparatively.