I bought 2 of these (but Marine White), just got them last friday and I'm still thinking on how it would be the best way to install them as the manual doesn't help much... it doesn't even say how to mount the screws.
I saw one video or page where there was some very good step by step instructions for the 250 (all you can find is for the 130...), but I lost it and can't remember where I found the link... I remember the guy used the spare metal parts (bought separatedly) that slid at the back of the Aquarays, I think he cut it in half and adjusted it to the sides of the Aquaray so it fit with the holes in the perspex cover, as if you use the whole metal part in a single Aquaray (it's like 45cm long, just one or 2 cm extra on each side), there's a little space on the sides for new holes and it might not fit exactly with the holes in the perspex. The problem is that it probably needs something to hold it in place (glueing it to the Aquarays). I bought these parts too, but I'm a bit lost, not sure if it will really be needed... you said you used the black plastic parts that came with the Aquarays? Did you use the plastic screws? I don't think they are very safe or useful... Did you have to secure the Aquaray to the plastic pieces bit a bit more like with superglue or just the screwing did the job? The plastic pieces seem to have some kind of larger hole for the screws that might even fit without needing to make an extra hole or perhaps just one should be made, at least obviously when you attach it to the perspex and if you want you can also use the metal screw for extra security... I am also considering installing it in the feeding flap, maybe with some adjustments it can be done. The other one will be installed at the back like yours (later, I want to install this more at the front first), and I guess I have to use the screws as usual as possible, there's not much to do there but to drill 2 holes and do it.
I am a bit disappointed that the metal part that they said would be useful for mounting it is probably useless, unless cut in half or a smaller piece and used as I've said, plus it's much harder to be drilled, makes the LEDs to be closer to the water surface (which they already are...) and the plastic pieces can work fine with a little thought. The only good part of the extra metal piece is that it can work a little more on the heat dissipation job, but I'm not sure how much it's really needed.
I tried to simulate how it would be if I assembled the 2 Aquarays using the plastic pieces with the 6 screws, leaving that gap in the middle as instructed... it's not actually useless (I thought it would cover most of the T5's, but it might not have space for the back LED to be attached.
Any suggestions you might have are greatly appreciated...