jetted tub install

i am installing a raised tub that used to be sunk in to the ground(concrete). how can i support the bottom of the tub? it is about 10" of space and i would rather not pour concrete.

You could build what amounts to a structural floor with joists and a plywood subfloor. A big tub could weigh half a ton or more...it needs to be sturdy. If the bottom is not flat, then set it in sandmix mortar to firm it up across the whole bottom of the thing. My unprofessional opinion.

tile on wall

thanks for the help jim, i'll probably do a subfloor since 10" of mortar is a bit much. i appreciate the input