Fishless Cycle Question

[reteer]

I've been cycling my 90 gallon reef tank with pre-cured dry rock and live sand. At the beginning of the cycle on 2/19/20 I put in a 8.45oz bottle of bio-spira and 20mL of Dr. Tim's ammonium chloride.

Day 2 - ammonia = 4ppm
nitrites = 0ppm

Day 3 - ammonia = 2ppm
nitrites = 1ppm

Day 4 - ammonia = .25ppm
nitrites = 2ppm
nitrates = 50ppm
after testing I added 15ml of Dr. Tim's ammonium chloride

Day 5 - ammonia = 2ppm
nitrites = 2ppm
nitrates = 50ppm

Day6 - ammonia = .25ppm
nitrites = 2ppm
nitrates = 50ppm

Day 7 - ammonia = 0ppm
nitrites = 2ppm
nitrates = 50ppm

Day 8 - ammonia = 0ppm
nitrites = 1ppm
nitrates = 40-80 with API test kit, 50ppm with Red Sea test kit

Day 9 - ammonia = .2ppm
nitrites = 1ppm
nitrates = 50ppm

Day 10 - ammonia = 1ppm
nitrites = 2ppm
nitrates - 40-80 with API test kit, 50ppm with Red Sea test kit

Day 14 - ammonia = .2ppm
nitrites = 0ppm
nitrates = 40-80 with API test kit, 50ppm with Red Sea test kit

Day 15 - ammonia =.2ppm
nitrites = 0ppm
nitrates = 40-80 with API test kit, 50ppm with Red Sea test kit

So its actually been about 3 weeks because I didn't test parameters every day. I haven't added ammonia since day 4. should i be adding more ammonia or doing a water change to bring down nitrates, then adding more ammonia to make sure the cycle is done or is this cycle actually done? I'm not sure why ammonia went back up to .2ppm after day 8 either after it was 0ppm. Please advise, thanks!

 

[Sk8r]

Drop a very small pinch of fishfood into the tank and see if it gets a spike. Go on doing that once a day until the tank doesn't spike. When you have no ammonia, you can then start working on your nitrates. As for your mystery spike, possibly water soaked into a cavity in the rock that had some organic matter in it. Possibly it was a test anomaly aka oops. Such happen. Personally, I've only ever used just plain fishfood to cycle, no potions, nada----drop a flake or two in daily until it spikes and goes down, so what I recommend above will both provide a little more food for your bacteria as well as serve as a test of when it's actually through cycling. ---And even after it IS cycled, treat it gently: little changes, no big ones. Your bacteria will still be building.