Sounds interesting edgerider. I don't have any experience with what you are describing, but having friend who own something similar, I thought I'd speak up. I'm not sure why you are considering a dome over it. If you are in a hot and dry location, I would for sure have a covering about, perhaps with some louvers that you can open and close to protect yourself from the sun, and perhaps rain/dust storms, or whatever. I would certainly leave out the sand in the bottom idea, since keeping the water clean and filtered is going to be a big enough task. I am guessing that you have electricity, so I would go with a regular in-ground spa filter system. If you can afford the cost, make sure it includes a heater for those cold nights when you want to sneak out there in your robe for a dip with the Mrs.!