Hi. I have three adult male guppies. Two days ago (7/9/17), I switched them from a 5.5-gallon tank to a 10-gallon tank. I rinsed all the new stuff thoroughly before put it in the tank or on the tank and I scrubbed the inside of the tank with one of my aquarium sponges (without soap or any other chemicals, of course) with some water. My guppies having been swimming more slowly than usual for the past two days. The only two potential causes I can think of are that I know the nitrates went to 0 ppm and they were at 5 in the old tank and that I haven't yet added enough crushed coral to the filter for the new tank because I keep forgetting and so the pH went down quite a bit. How much more crushed coral should I put in? I have two tablespoons in there. Actually, I just realized I forgot to feed them today, so that may be what's causing it today, I guess. But I know it's common to skip every other day of feeding guppies if a tank is cycling, so it doesn't seem like that could be the cause. If it's the nitrates, what can I do to fix it other than just waiting for the nitrates to go up? Water parameters from the last two times I tested it: 7/1/17 Nitrate 5 ppm Nitrite 0 ppm Ammonia about 0 ppm High range pH 7.9-8.0 7/10/17 Nitrate 0 ppm Nitrite 0 ppm Ammonia 0 ppm High range pH less than 7.4? pH 7.6 I planned to test it on 7/7, but I couldn't do it (I don't remember why) and then I just completely forgot about it until the night of 7/8, when I had already decided I was getting a new tank on the morning of 7/9, and I was thinking that the testing could probably wait 12 hours, especially since the new tank is much bigger and would therefore require a big water change. Then after I set it up, I figured that I should give the tank a day to get itself properly working for filtration because if I tested it now, I might get a result that just wouldn't be true in a few hours, and if it were a bad result I got, I'd try to fix it and maybe accidentally make things worse. Their gills are getting red now, so I'm gonna go test for ammonia, nitrite, and nitrates again.