[I bought this item from “AVC Online Outlet” for £439 on 15 April 2019] This spa is very hard to fault. I am 6’4” tall, and I can lay out, fully submerged. This makes it “bigger” than the circular variant, though they both hold 930 litres. I cannot find any bigger dimension in any inflatable spa: 164cm, corner-to-corner. It heats to 42° and I like nothing better than a hot bath. But 37° is comfortable and my ideal. Set-up was simple. I put it on a double thickness of Amazon product B075FW6BT6 (you can search on that) which is perfect: I used two 3×3 layers. Inflation was fast. You can set the spa to heat in n hours’ time. So I can use Economy 7 power to kick things off. But a tank of domestic water at 72° (mixed to deliver 40°) is a good start, too. I’m running this off a 9.8kW photo-voltaic array (bottom-left in the Google Earth picture). I was fed up seeing power being exported to the grid — without any benefit to me — so I am running this for free. The panels heat domestic water tanks first, then on a bright day I can run the spa from 11:00 till 18:00. Here are yesterday’s figures: 20:00 (day before) 32.0° (then power off). Noon: 29.5° (then power on); 17:00: 36.6. So it can heat up by 7° in five hours. It’s essential to add the bladder (B012Y1M63Q) as that insulates the water overnight and ensures that the cover cannot collect water. Anyone complaining about the top retaining water is just a thick-o: buy a bladder. I use item B07HRR9TBK to dispense chlorine, and after a month, the water is clear, even though it’s not been used since our heat-wave Easter. Generally, heating as above on Wednesday, Thursday and Friday will bring things up to a toasty 37° for the weekend. For a final kick you could set the heater to turn on at midnight, targetting 37° and know that you’d pay for just a tiny bit of peak-rate power. One minor drawback is that, though you can tell the heater to start in n hours, you can’t tell it to stop. My workaround for this is to fit a plug-in timer that switches ‘off’ at 06:00 (or whenever your E7 ends — bear in mind that this varies by supplier (infrastructure, not billing) and often stays on GMT all year). Careful reading of the manual says you should not use such a mechanical timer, but I cannot think of any good reason why not. The bubbling is energetic — possibly too energetic, and cannot be regulated. A minor quibble. Who knows how robust the material will prove to be, but it's heavy and solid when inflated, and looks really smart. Buy yourself a B0054XGJEY and attach it to the tub with B00N0W87WS; the sensor sticks on the filter. Add a couple of these (B00B4DLGGY), grab a book that doesn’t need to be kept dry and you’re off. — Best £500 I’ve spent in a very long time.