How high to put my lights above my tank??

First my apologies for not being on here in so long. No excuses (not that type of person), just haven't been here.

I just purchased a light with 2 175 watt metal halides (MT175/aqua2/hor) , and 4 UV (fr65/atw/st) compacts and 8 blue moon leds. How high should i put this fixture above my 55 gallon tank thats 22 inches tall. Im was using a fixture with 2 HO T5's, whats your recommendations for the introducing in this big change in light? I can turn everything on separately, so MH's for only 3 hrs at first then 30 min more every day to my target of 10 hrs?? I only have mushrooms and star polyps right now so im not to concerned. Im putting the light up right now so a speedy reply would be much appreciated. Thank you all in advance for your valued advice.

 

I would start with that fixture about 12 inches of the water surface - it will possibly be OK for the long term also , although some may move down to 10 or even 8

what corals are you currently housing in the set up

your plan - regarding turning on the lights seperately is a good one
you could run the PC for the 10 or 12 hours that you do now
and gradually increase the MH time

I would not increase on a daily basis though - it would be better to run each time you choose for a few days to give you plenty of opportunity to monitor the inhabitants

starting with 3 or 4 hours per day and then increasing by 30 mins every 5 days to 1 week is possibly a better idea

alternatively you could buy some screens and place 4 or more layers of screen above your tank - run all of them for 1 week at normal time - 8 - 12 hours, and then remove a layer of screen ( this means your providing 25%, 50%, 75% and then 100% of the light to the corals) again monitor the inhabitants and be prepared to slide back a screen if corals seem to be struggling with the lighting

Softies and especially LPS corals are your best indicators as to your lighting being to much for them
unlike SPS corals, they have the ability to reduce their body mass in order to reduce the amount of light they are expossed to

so if you see LPS corals starting to close up, that is a good signal to turn off your MH lighting or add back one of your screens , irrespective of how long it was running on that day

Good luck with it
sounds like a great upgrade to me

 

I did it the wrong way, but I went from a 4bulb t5 ho to a 2 175w halides + 2 90w actinics + 4 led moonlights. I have legs on mine and is about 5 inches or so away from my tank. I just put it on there and turned on the lights, although my lights are about 9 months old and nearing to be replaced. My room is at the end of the house and it gets really cold, so the light keeps my tank about the right temperature during the day and then i use a small room heater after my lights go off so its not so cold and i dont freeze to death.. my corals are doing a lot better with the new light as well.. I'll prolly buy a chiller for it for summer, but I do have a window A/C unit..