Hi Jules,  Lee here but Joe has the same number of letters so it'll do   

Love the brackets fella, just what I would do, I certainly wouldn't go to the options list for overpriced branded brackets 

Some manufacturers give details on the recommended mounting height, if not then it's play by eye.

You obviously don't want your lights so high that you get the cone of light spilling over the sides of the tank lighting up the carpet, coraline carpet isn't a great look 

There will be a sweet spot as you move it nearer where the light doesn't spill over then it depends on how you like it and your corals respond.

I assume there is some intensity adjustment in the lights too for further tweaks.

I'm totally new to LED lighting so not much help beyond that point I'm afraid, I just bought my first one.
I almost went with a new halide set up, from the local hydroponics shop mind, they're cheaper than aquatics outlets 

Thanks Lee, there is another element to the position, and that is catching the light down at the sofa.
Before, when I had Halides and actinic T5's the tank being so high would let light out directly into the eyes of people sitting on the sofa at the other end of the lounge, it's an unfortunate product of making the tank appear to sit on the living room cabinet, in fact, to do any maintenance at the bottom of the tank I need to stand on a stepladder, and the tank itself is only 20" tall.
Clearly, I'll have to put up some sort of lightweight surround 1. to stop light bleeding into our eyes, 2. to inhibit the cat from jumping up to the top of the tank (you see I found her previously drinking the saltwater from the tank, god knows why) and our cat can jump four feet in the air from a sitting position!
Heaven only knows what she'll think of the brightly coloured fish later down the line, as it is, if we want to watch a nature documentary, we have to send her out of the room or suffer a scratched LED screen!

FINALLY got the lights on. Now you can see the tank a bit better.
I don't know why, but I had to up the red LED spectrum to get an image of what it actually looks like to the naked eye, first shots had a deep blue tint that I couldn't see.

Ok so I took out the trickle filter, sad to see it go, and not at the same time.Maybe I was relying on it so much that my nitrate production was through the roof (well, at least 10ppm after the recent test).As per your advice people, I'm now reliant on the living rock and 4x Boxtech (similar to maxspect product) in the low flow area of the sump, I'll probably put more of that media at some point, but after I've built the algae scrubber.The latest thing to happen was a brown dust-type algae throughout the tank, so I switched the lights off, did a nitrate test (ammonia and nitrite showed 0ppm) and found it high.In accordance with tried and tested methods, I'll do a few water changes to get it down, and crack on with the algae scrubber, so that can kick in to help with the nitrate/phosphate further down the line.The seneye is ordered, and a Win 10 tablet secured s/h from ebay so I can make my own server as per link kindly supplied by ajm83.Here's hoping I'm on the right track with my methods.I'll repeat what I said before: anyone who doesn't live too far from me wants to check their PAR, I'll be happy to pop down and we can stick my probe in their tank and take a reading.

I may well take you up on your PAR offer at some point sir!

Be happy to do so.
When and if I go to a LFS in Herts, I'll announce in case there's anyone in that area needs a PAR reading too.