I want to put my 8x8 hot tub on handi pads ,but have a slope to one side will it be OK to fill with dirt and pack it hard put down sand and then my hot tub

I wouldn't rest a hot tub on top of sand. You may need a concrete slab, or a pre -fab slab--normally provided by the manufacture.

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Better to dig into the high side than to try to fill with dirt. I did that, laid concrete block down covered by tongue and groove pressure treated polywood, lasted 25 years.