Sorry in advance for the essay, but I hope it is maybe some helpful info....
You should test nitrates just once to see if there are any present, as that would indicate that your cycle is moving forward too. But it has really been too long for you not to have seen any movement, so I agree that something is wrong, thus all of the questions.
I really think you need to rethink the whole amquel thing. Its not just about the false readings. When the ammonia that you're adding in on purpose gets changed to a different form by the amquel, it could be hindering your attempts at cycling. You do not need to neutralize ammonia in a tank because thats what the nitrogen cycle does. High level, the nitrogen cycle converts ammonia to nitrite and converts nitrite to nitrate and you take nitrates out by doing water changes. When you take that first step away, the bacteria necessary to convert the ammonia to nitrites don't develop.
Also, I wonder if your ammonia is a lot higher than 8. Many test kits only register up to 8 and at any level higher than 8 it still says that it is at 8. When you have a high concentration of ammonia in the tank, those bacteria are also hindered from multiplying. That is why I usually pick a 4 or 6ppm measurement because you can tell on the kit that there is still ammonia in the tank, but not too much. You really only need to get that tank up to a detectible amount and then wait.
Bacteria etc also need oxygen, so running your filters and a powerhead is great, as long as the surface is being broken...so if that powerhead isn't breaking the surface of the water, see if you can angle it to do so.
Have you tested your water temperature with another thermometer to check for accuracy? If the water is too warm, bacteria will not grow...same as if it is too cold. I usually shoot for 80-82 just to be safe.
The reason I asked about if you have anything else in your filters is because same thing with amquel, if you were to have ammolock or nitrite pillows or something in your filters then it can also screw with the cycling process.
Last but not least, yes, there are some good bacteria products and some aren't worth anything. The only ones that I've ever heard of having any kind of actual good effects are biospira (which is refrigerated bacteria and best used on a tank where there are very low ammonia/nitrite/nitrate readings) and one called... shoot Stabilize? Stability? I'll have to look it up, but its made for tanks that are currently cycling and already have ammonia/nitrite/nitrate readings.
If I were you I would do this:
1. Get some generic water conditioner.
2. Turn off your filters/heaters.
3. Do a large water change & do not use amquel.
4. Turn your filters/heaters back on.
5. Wait an hour & then test ammonia level. If it is really low maybe add a cap ful of ammonia. Wait an hour and test again. You only need to get that ammonia up to a detectible level on your test kit, somewhere around the middle of that strip.
6. Leave the tank alone and test in a couple of days. If your ammonia is still the same, then leave it a few more days. Not really a whole lot of use testing nitrites or nitrates if your ammonia hasnt moved.
A big water change is not going to hurt your tank for any progress that it may have made because those bacteria mainly colonize on your filter media and are not free floating in your water. The only way that would happen is if you left your filters running and allowed chlorinated water to come into contact with your sponges, which is why I suggested getting in the habit of turning filters/heaters off while doing water changes.
i hope you put some pics, and also what kind of fish are you going to put in
