I've been lurking for a while trying to find the fish 4m I wanted to use. I like the structure here and there is great beginner information. I have history in this hobby as a kid. We had 16 tanks and my favorites where the Oscars and Convicts. But my parents managed the cycle. Now I'm trying to get back into it with my kids. Currently we have a 10 gallon tank that had Mollies and still has Tetras and a catfish. I already wish we would have gone with a 30 gallon to help with the cycle as I'm struggling getting it where it needs to be. So with that introduction, I have one question to help me determine if I'm going to buy a 100-150 gallon tank. I'm reading through hard water questions and some apply to me directly and some don't. Will I be able to use my hard water to fill a 120ish gallon tank? I ask because I want to purchase a tank and fill it with a couple Oscars, convicts and maybe firemouths. But I cannot purchase water for every fill on that large of a tank. I also don't want to fill 10 5gal buckets and let them sit overnight. It just doesn't work with 2 young kids. My water hardness is around 150-200ppm. Thanks for adding me and all the information here!