I started with small freshwater tanks, 10,20 & jumped to 135 gal. pond & then went to a 55 gal. salt in HI. I didn't know didley about salt so got live sand, live rock & saltwater at the beach. I was so dumb I didn't even know it was live sand & rock, & then I caught all the fish & eels that went in it. When we moved to the mainland I started out with the smaller freshwater tanks again, went to a 45 gal. & then we started a 90 gal salt tank, got a 125 & also have a 35 gal. hex, plus 4 ponds outside. Go bigger. It will save you lots of time & money & don't be afraid to take your time & do it right the first time out. My hubby keeps talking about going 250-300 next. Yikes, I'll be living in an aquarium very soon at this rate.