I live near Chicago, IL and I have an 36,000 gallon in ground pool with and 72" diameter spa that overflows into pool. Last season the company that closed my pool/spa poured antifreeze into the 4 cemented airblower outlets (9 hole caps cannot be removed to put winter plug in) on the floor of my spa. Then lined the whole spa with plastic liner and then filled with water. This seemed right except for the plastic bag bulging out from winter cover looked weird. They also removed the lights and tied an anchor so they sit at the bottom of the pool and the spa.
This season I decided to hire another company that has a good reputation as well. They drained the spa completely, plugged the two returns and poured some antifreeze in the air outlets and return basins. Then left the spa empty and then put the cover on withOUT taking out the lights from pool or spa.
Should I be worried that the spa will freeze heave up from lack of weight of the water?[attachment=0:y6weej1i]Spa Plugged water port.pdf[/attachment:y6weej1i]