Everytime I move or start a new tank that has old sand I dump a bottle of bio spira or Jason (aquarium design) has something like it he gave me to get it going fast and I have never had a spike since using those. On the 3 & 4 day is when i would do a water change those are the days that a tank uasual spike. As for your fish they should be ok mine were in a smaller container for 2 week waiting for a tank to go in to get here. I had 7 fish I gave them live rock and a korilla. I even put a light on it for them. I have a skimmer you can borrow until you find one you want I wont be using it anytime soon so let me know if you want to use it.