So my 6 year old came to me asking for a fish. I obliged and we purchased a 10 gallon tank, gravel, bubble maker, some fake plants/rocks, AquaSafe, SafeStart. I followed the directions of rinsing off all the "toys", rocks, and inside of the tank. Added water until it was within 2-3" of the top of the aquarium. From there we setup the filter and added Aquasafe and let it run for a day. After a day I added 10-15ml's of SafeStart, went to the pet store and bought 3 fish, I let them get used to water and finally set them inside. 2 of the fish died the first day so I started to research fish tanks and found several sites explaining the nitrogen cycle. After reading a few sites it decided to get an API test kit and do a 25% water change. I then added the rest of the SafeStart as it sounds like I was supposed to add the whole bottle not just a few ML's. So it has been a week, we still have 1 fish alive, but the ammonia is at 4.0 ppm, Nitrite 0.0, Nitrate 0.0 and a ph of 7.8. My question is what is to do next, since I did a water change than added the safestart, did I basically kill all the bacteria? Should I pour another bottle in the filter in hopes of it taking? Should I do another water change first to bring down the ammonia? Should I buy some stuff to neutralize the ammonia? At this point I should have bought my son a hermit crab like he wanted. Thanks for any help you can provide.