Hello All- I'm new at the aquarium thing but not SO new that I don't have a clue. I kept a 10 gallon tank for years with wonderful success and just recently decided to get back into the hobby of fishkeeping. About 4 weeks ago I set up a 20 gallon aquarium and decided to go coldwater so I started out with a medium sized comet goldfish (approximately 3in long) and a 2in black moor. All went well until about a week ago when the water went cloudy and smelled foul...needless to say my tank had succumb to "New Tank Syndrome" Unfortunately I lost both of my beautiful fish despite frequent water changes (every day) which I read to be the best method for getting through the cycling. I've still been performing water changes to get the ammonia levels down which are now at 0 but I know that for your tank to be completely cycled the Ammonia spikes first, then once it goes down the nitrite levels spike and go down and then the nitrates do the same. My problem here is that the ammonia levels are at 0 and have been there for several days and all other levels are normal as well. I have a 5 strip test (Nitrates, nitrites, hardness, alkalinity, and PH)as well as a seperate ammonia test so I can do all of my own testing. Does this mean I need to put some more fish in the tank to start the cycling again? Also, I've decided I'd like to go back to a tropical tank as before (several years ago) but currently I do not have a heater in the tank, however, my thermometer is reading 78 degrees constantly. Do I NEED a heater at this point and time? I would like to start out with a school of about 5 Tiger Barbs as they were on my favorites list in my last tropical tank. Any advice would be great THANKS in advance!