Hello y'all. I am new to the hobby and I have a few questions. I really don't want to mess up so I need some advice. To start off, I have a 5 gallon tank. I have two tiger barbs and a Pleco. I have a small filter ( that I hate. I can't tell if it's working!). Ok so my questions. What is cycling? Do I have enough barbs? Is my tank too small? How do I test my water? Please help.