you are dealing in test drifts and misreads, the zero point reading on your kit for ammonia does not matter. its movement that does and the # of days your tank has been underwater, with 30 days being the universal completion date which you've passed.
Here's how cycling works, though you'll see many different versions of cycling variations posted as well. This one is unique, and works 100% of the time in fact so its really reliable.
details:
1. see all cycling charts on google pic first. millions of search returns show patterns, not related to bottle bac, ammonia levels or anything else. The constant patterns are indeed: ammonia nitrite comply by day ~30, they don't re spike. There aren't charts of nitrite and ammonia complying by day 90 or 60 because it doesnt take that long. on most charts, its in between day 20-30.
That's because @30-40 days, where you're at, is the universal deposition time for aquatic and marine bacteria. They are there faster, but all tanks will comply with correctly-tested cycle params by day 30. (correctly tested is key)
2. correct testing, how to make your test kit prove cycle is done:
-too many things cause misreading in today's ammonia titration kits. We collect misread threads in cycling threads and its massive, test error has people thinking cycles don't comply off already-known timing and they do, we just aren't arranging tests correctly to see it. The way to do that is look for change in your test reading after new arrangements, not the 0 point reading. You can either do a basic water change and begin reefing, going off already-known timings to stamp your cycle complete, or, if you must test it, then you do it this way-
-change out your tank water, or polyfilter it to known zero ammonia. However you want to make your tank water zero, do it. When its zero, then you add liquid ammonia to the degree that it makes the first increment change on your test kit, up from zero. Not to 2 ppm, but the first increment of free ammonia, notate that color and stop.
wait 24 hours, it went back to the prior color. done
the movement back down within 24 hours is proof of bac/cycle completion and we've arranged your colors to indicate it correctly now. You do not have to go to 2 ppm to indicate a complete cycle. testing the wastewater, after many random additions of ammonia, is why everyones test kits vary. We change that into a zero ammonia condition at the start, and then reference what the test kit shows as zero, to calibrate for the adjusted test. Sorry its so complicated, you can thank titration testing for it lol
