There was a bit on places banning mermaiding in
this thread. Basically my input is to go to the manager or the lifegaurds and educate them as to why your tail is a swim AID and piece of water equipment, not a swim hindrance or danger. Explain to them the materials it's made of and why it's suited for water wear. Offer to do a swim test for them in tail to show them you are capable. Some have suggested legal liability waivers as well. For those who go pro performer's insurance is a big weight off everyone involved, including when you're at a pool for practice (not an actual gig). This may not always work, but it can't hurt to give it a try! Education is the first step, right? :)