I've got a problem that I think I know how to fix, but I wanted to get some input in case there's something else and/or better I could do. I'm experienced with cycling tanks, most specifically really little ones (I have several) These are 5g and 10g, and I cycle fishless. I did something that I should have known better about for these current changes. But now I've got the problem that's going to be a challenge. One tank has ammonia, no nitrites, no nitrates. I'll give you the steps for what I'm doing so you can hopefully help better (those who are kind enough to take pity on my fish, if not for me), and also for beginners who might be making big changes like this and want to see a way it works well, and a way that make me sub-beginner. I recently decided I wanted sponge filters (as my only filters) and also black sand in two of my tanks (already changing two major things at once, stupidly, but I thought I had it covered). For the ten gallon (very stable, great water quality), I had good sense: I bought a new 10 gallon, put the sand in, added the water, moved my rocks and plants over, piece by piece from the old tank, installed the new sponge filger, then moved the filter (Aquaclear 20) unchanged (nasty-looking but washed-in-tankwater floss, bioballs, a sponge), and the heater. I put my boys and girls in last, and will run the old filter along with the sponge for three or four weeks before removing the old filter. It went great. The Cory Cats are now in sand-heaven. They got together and spelled out "THANK YOU, WE LOVE IT!" in the sand. So. The 5 gallon: I did not have a new tank for this like I did for the 10g. In it lives the most fun betta (he has nothing but arrogant contempt for the world. I don't think he's a Siamese Fighting Fish, actually, I think he's a Siamese CAT, and his attitude is more French than Siamese). Also a dwarf pea puffer who torments the betta with his cheerfulness and cuteness. Here's how I did this move and put these adored animals in peril. This 5g is one of the little all-in-one PetSmart nano setups. It actually was the thing that prodded me to do this project in the first place, the pump is dying on me ("the pump is broken, might as well change everything while I'm at it..."). For those who don't know this tank, there is a compartment on the side that has a grill in the panel, and water flows into the compartment by way of a submersible pump like the ones on pet fountains, drawing it through a filter cartridge. There's a long filter (I converted to pinky filter floss I cut to fit the cartridge frame last year) and the pump pulls the water through that. The outflow is another hole in the panel. You can stick a heater back there (I have just a plain vanilla 50W, the one thing I DIDN'T change). The filter floss I was using has been rinsed in tank water several times over the last few months, but is nicely aged and working well. This tank was stable with great water quality before I made the change. No new tank to switch over to like I did with the 10g, so most everything went into bowls (even the snails had a bowl) The bowls were full of Prime-treated water. I cleaned the tank, put the sand in, added Prime-treated water, installed the new sponge filter, replaced everything else, then removed the ailing pump. I left the filter floss in the back, vaguely thinking "bacteria, will seed the sponge, blah blah blah, what could go wrong?" Here's the idiocy. The pump was very weak and cut in and out sometimes (hence the change)but was still working well enough for the fish. But I wanted the pump out, and thought of the floss pad as the main thing. But I didn't consider until too late that the problem would be that with no more water flowing directly over the floss, the bacteria was not supported. And on top of that, removing the gravel took another source away. Oh, and I decided to get rid of a few of the plants. And though the snails got a bowl, the rocks didn't, I set them on my kitchen counter throughout this, and they were bone dry when I put them back in. So you know what happened. I've got a clean, beautiful tank with an awesome new sponge filter bubbling away, and two fish I dearly love who I need to pull through this thing I've done to them. Here's what I'm doing: --I left the floss in there (lol, hope springs eternal) --I don't have anything else to seed this tank with, it's a sponge, and I don't have a sponge from a cycled tank to "borrow" -- this project is about me switching to sponges, so they are all new. The only other cycled filter, the HOB, has to stay on the 10 g, it's the only BB support until it has seeded the sponge filter there, and that will be a month) --I'm doing fifty percent water changes twice a day. This is keeping the ammonia at 0.5. It never went higher 1.0 (yet; here's hoping) --Feeding EXTREMELY lightly (one more thing for the Betta to be bitter about). --I put more plants back in, so it's pretty heavily planted. I know people have definitions for this; my heavily planted means big plants everywhere (bundles of anacharis and two big sword plants), and little plants in the between spots). --It hasn't gotten to the point where I want to Prime-dose is heavily, and I do not want to use ANY kind of Safe-Zyme-Ultra-Cycle-Helper thing, so I don't want that as an option. --Bumped up the heat a bit, 80F; both fish are probably digging this, at least I can give them a spa experience; my MANY pink snail are signing a petition for AC, though) --Waiting, worrying, and.... Anything else? Thank you, those who have read this long tale. I was hoping by going into detail I'd think of something in the process, but it just made me feel more sure that I suck. I appreciate any advice.