1. 20 gallons, 75 gallons, 120 gallons, and 5 gallons.
2. Waterbox, Marineland, custom, and Aqueon.
3. My Waterbox was my first reef tank and is still my favorite brand but I went to the fish store without doing much research when I was a beginner and I was recommended it so I bought it. My Marineland I got from someone else after my other new Aqueon/pufferfish tank leaked recently. The 120 is my school tank and was a custom tank from Glasscages that was previously owned and donated. And my little 5 gallon Aqueon is my little observation tank currently housing a white tail bristletooth and may be turned into a seahorse tank soon.
4. Go bigger always go bigger especially if this is your first tank it will be much easier and so worth it. I’d personally avoid Red Sea and Aqueon tanks with all the issues they’ve had lately and the poor quality. I love love love my 20-gallon Waterbox but I wish I went bigger for my first tank. And Marineland I’ve found to be good also I’ve heard great things about SeaPora, Innovative Marine, Cade Aquariums, and Planet Aquariums. But if custom is an option for you absolutely go with that. Spend the extra money upfront it will be worth it. Here’s a link to my Instagram where I share all my tank photos.
https://instagram.com/an_afishionado?igshid=OGQ5ZDc2ODk2ZA== And here is Hewbie my porcupine pufferfish in his original tank before it leaked. He’s my favorite little buddy.