i too would say at least 7x4 ft for the length & width. you can seal with what is now one of my favorites (thank you Toby_H) Drylock cement sealer.
It can make it water tight, It makes a rough stone like finish, & most places carry a tint for it.
Humidity - Yes water dish under a good heat source or a heat pad under the water will usually get 5-10% increase in humidity
I like to use a Cat Litter Pan as a water dish (comes in many colors and like 3 sizes usually under $5 for the XL)
Zoo-Med repti-fogger is good, or even a child's cool mist vaporizer right in the cage set on a multi-time timer, Or many companies
offer "do it yourself" misting systems (or even google it and you can make a nice homemade one)
1.1.0 Argentine Black & White
1.1.0 Red Tegu
0.0.1 Blue Tegu
0.1.0 Hypo Red Tail Boa
1.0.0 Lazik Tiger BP
1.0.0 Normal Paradox BP
1.0.0 Normal BP
1.0.0 Cuban Tree Frog
1.1.0 America Toad (1 Red & 1 Green/Brown)
1.0.0 Masked Ferret
1.1.0 Children
ASF Rats, Rats, & Roaches (Discoid & Dubia)
& More to come
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