hi nichole
I think your tests are probably ok and you've accidentally pushed your cycle back a bit. The stuff in your water that can suppress nitrifying bacteria would have been the acid from the pH crash.
The 3-4 drops per 10 gals is not necessarily an accurate dose. Might be, but then again…. Ammonia concentrations can vary from one mix to the next or concentrations can drop as the mix ages. Thats why the protocol is usually "enough to get to 5ppm" and not a specific amount. I used 1/4 teaspoon for my 30g, although I think that may have been a little high (long nitrites, 30 day cycle). I think 3-4 drops/10g would have been a little low for me. It'll work in the long run but it may not be optimal.
The cycle isn't established until you are at double zeros: 0 ammonia, 0 nitrite.
It does sound like you're close.
It seems to me that a lot of times it sounds like the cycle is something that happens once at the beginning and then is finished. Its really something that isn't happening at the beginning that we're trying to get going safely. Then it will happen automatically and continuously. The nutshell rendition: the fish produce (or we dose) ammonia, bacteria converts that to nitrites, other bacteria converts nitrites to nitrates. Generally the process ends there and nitrates tend to build up. The whole process tends to acidify the water.
The key points: ammonia and nitrites are dangerously toxic to fish -- the cycle isn't established until you have colonies that can process the full load as fast as it comes in. Nitrates are not as toxic -- you'll want to keep them low but they will be present in your tank. Water changes are the most common method of nitrate export. By the time you have finished a fishless cycle you'll probably have a pretty high level of nitrates so the last step is a large scale water change to remove them before the fish go in. Generally you want to keep the nitrates at least below 40 ppm and preferably under 20.
After the fish are in there will always be more ammonia, more nitrites, more nitrates, more acidification. The bacteria will take care of the first two, regular water changes will take care of the second two. There is a bunch of stuff (like nitrates) you'll want to remove, and stuff (like carbonates) that are being used up and need to be added back in. Once you're up and running the normal recommendation is for a 20 or 25% change once every week or so.
The coral in your filter should help give you a nice stable pH, but you can have too much of a good thing -- keep an eye on it to make sure your pH isn't drfiting up above where you want it to be. I need to supplement my buffer and you may as well. Or you may be overcorrecting a onetime incident caused by a lack of water changes and unusually high amounts of ammonia. Just something to keep an eye on and very adjustable.
You're almost there!
oh well it seems to have worked.
