I’ve tried this. Was gifted a voucher for Christmas. It wasn’t so much a tank with a lid, but rather a very shallow square pool- but I have seen the ones with the lid and don’t think I’d like that one. You could have the lights on or off. And music playing the whole time or just 10mins before your time was up- I had it on the full time. I have fibromyalgia, so get a lot of aches. Ive only gone once so hard to tell if it would have any benefits but I did feel relaxed afterwards. The time went rather quick but I find it hard to…. Relax…. Meditate, so it was hard to just float there.