Look, these lights work fine. No better than your regular T5 with an inline dimmer switch - which by the way would be much cheaper.
Design and build quality are awful though. These lights are designed without any feet, or any way to logically sit on top of an enclosure. You can purchase an aftermarket bracket if you want to sit them on top of your tank, but otherwise, you'll be resting the light on the two cylindrical rubber bulb inserts for it to just roll around willy nilly on top of your tank. If this was a cheap light, I would understand. It's not a cheap light.
I contacted Arcardia about this - no reply, 1 month and counting.
My second gripe is, the onboard memory that you require to have the light function properly if you ever actually close the app (like any normal person would) is driven by a battery that is flat when it arrives. Replacing this battery doesn't cost much, however the directions to change the battery say "Insert something flat under the plastic tab and lift gently". Wow that couldn't be further form the truth. The clip they use on the underside of that plate is so rigid and overengineered that it will bend the aluminium light body before it functions as intended.
I have plenty of Arcadia lights, but this one is a never again. There are better options for less money.