Ok, I had a 2.5 gallon all set up with a Betta in it. I also had a 5 gallon all set up with a Betta in it. I moved the Bettas int o a 20 and a 10 gallon tank and I wanted to keep the 5 gallon set up. I put the sand and plants and filter from the 2 gallon into the 5 gallon without rinsing any of it, only thing new in the tank is the water. Will my 5 gallon need to cycle or should it be safe for fish now? I did this 3 days ago.