I finally was able to set up my second attempt at a 55 gallon freshwater planted aquarium - it is almost complete as I am awaiting shipment of the last group of plants.
I have a question about the best height level for my Hagen T5 HO GLO lighting fixture with 108 watts total over the aquarium. I have a Top Fin 55 gallon tank with the black plastic frame and middle separator. During my first attempt to set up this tank I tried laying the lighting unit directly on the glass top but felt that this was not good due to the proximity of the heat of the bulbs to the plastic parts of the tank and plastic hinged glass tops. I was able to have a local glass shop trim some glass off the hinged tops so I could mount the Hagen T5 HO fixture mounting bracket. This bracket has four height settings and I was wondering which level would be best to rest the light fixture on to maximize plant growth, etc.
Thanks for your time and advice.

John Remsen

Johnny,

I always go by the idea that the closer it is to the water's surface and the less obstructed the light bulbs are between them and the water, the more light you'll get into the tank. Conversely, the more stuff you have in between (especially dirty or opaque stuff) the higher the heat buildup will be.

I've got a 48Watt T5HO fixture sitting directly on top of my ten gallon's full glass hood, and no melting problems thus far. However, it does get pretty hot. I would generally recommend an inch or two above a hood for high-powered lighting. Without a hood, I would strongly urge a splash screen (most fixtures have them) to protect the bulbs, that way you can get much closer to the water.

Many on here use egg crate from Home Depot or Lowe's as a place to rest their fixtures on over the tank, FYI.

Hope this helps!

__________________
Officially fishless until after the move....tune in later for details!