I've been seeing a lot of these tubs being given away lately; it seems that the 'fashion' has passed.
With the increased use of second-hand tubs, it seems to me that many will already have problems ... or, even, be damaged in transit. I strongly suggest everyone bone up on their troubleshooting skills.
For those wishing to get fancy .... it's quite reasonable to get significant heat from the sun. That is, you pump the water through a coil of 5/8 irrigation tubing atop the gazebo, enclosed in a safety glass faced case. I've seen these coils used to heat full size pools; they should be even more effective with a smaller tub.
The fun would come in designing the controls
