In my opinion a 10gal doesn't have enough floor space for an adult leo (10"x20"
. Boo seemed so cramped that i moved him to a 20gal long and still i think he could use more room. My 36"x12"x12" tank (unsure of the number of gallons that is) is where Zoe is, and she's less then half the size of Boo. She absolutely loves that tank. I hope to have all of these guys in their own twenty gallon tanks.....currently i'm drawing up the plans for a unit to hold them, but if i can't get it to work, 15gallons (24"x12"12"
is the smallest i'll go. Of course these guys are my pets, so i'm going to spoil them
I have no problem with breeders using racks at all, i would too if i had that many animals and i was breeding.
A 120 gal tank..........WOW that would be soooooooo fun to set up. It should be quite a centerpiece when done.
Red 
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Crested Gecko Zeek:1.0
LEOS: Boo: 1.0 normal , Bronx & Nala: 1.1 blizzard,
Lily: 0.1 patternless, Abby: 0.1 albino, Zoe: 0.1 reduced pattern, Dot: 0.1 hypo
Chip: 1.0 papillion (small dog)
2.0 bettas