So we moved into a new home and I'm updating my indoor RT enclosure from a 3'x2' tub (I Know.) to a 8' diameter kiddie pool in our new spare bedroom. I was wondering if there has to be substrate in the whole thing? that would be A LOT of dirt (and money) to fill the pool even an inch let -alone 3"-4". So could 1/4-1/2 of the pool be dirt (dirt meaning 70/30 coconut coir and sand) and the rest be bare? it's a soft kiddie pool not hard plastic so he has no trouble walking around. And there will also be a large amount of hay in one corner (so to speak) because he'd rather burrow in that than the dirt anyway. Does this sound fine or do I need substrate in the whole thing? We just moved in today and he's already loving the space in just a bare pool with some flat rocks, hay, water and heat. Thanks