I had this light and even my zoas suffered, it was my first salt water and I had researched and seen that LEDS were the best bet with marine tanks and if you are on a budget t5 bulbs and thus assumed this would be appropriate but alas no all my corals even zoas high in the water started closing and then all were shut and my hard corals were going white (Bleaching, its caused by poor lighting amongst other things but this was likely the cause of mine as when I changed the lighting to a TMC 900 which is the perfect size for my m90 and low and behold within a week they were all but a couple that have cyano bacteria attacking them, doing my best to treat it with none chemical methods but its not going amazingly but not as bad as it could be either. I chose the TMC 900 as it was the best price for the power, when searching for a marine led be aware that most reasonably priced ones that actually work have to be suspended from your ceiling and unless you know where your supporting beams are if you have any at all is a nightmare. I know £400 is a lot to spend on a light but that is pretty much the cheapest light that will actually do the job and that actually functions properly, plus its fully programmable to internal timers you set yourself which is reasonably easy to do if you read the instructions and has a STUNNING blue spectrum and a lovely very white day light, the amber and red are great too, nice and subtle. Just my two cents but honestly I would not even open the box if it hasn't been opened and return them to the shop or sell on ebay and buy something better. Obvs shop option better as you might get a chance to get new lights on the day. If this is not possible then you will have no choice but to use the light, unless you don't have corals yet?