T5HO for 7', 200G Long Aquarium

[jkpq45]

Hello All,

Running two 4'x2' T12 fixtures over my 7' 200G long and the fixture hanging over the edge is driving me nuts. T5HO seems to be a good bet, but I could use advice on the following:

1. Light Fixture Quantity/Size. Should I run two 4', 2-tube fixtures for a total of 216W? These are skinny enough to stagger on top of the aquarium so they overlap in the middle. One 4' and one 3' fixture would fit, but would result in a 14% decrease in lighting wattage (down to 180W).

2. Lamp color? The fixtures I'm looking at (48" T5 HO Aquarium Light Hood Cichlid Marine 108W New | eBay) come with one 10000K bulb and one actinic. Will this be ~14000K? Will it be the wrong color? Looking for bright white, 6700K T12 bulbs appear too blue in my current setup.

3. Ability to grow plants. Even with the two 4' fixtures, I'm only ~1W/gallon. Is this enough to grow some plants? Can I supplement with CO2 for the lighting level? Is this considered "low light"? Will it look dark when viewing?

Thanks!
jkpq45

 

[huma-huma]

6500k will have a yellowish tint to it...10K'S have less yellow and more pure white. 12k moves toward the blueish white tint. 14k is pretty much bluish purplish.. being as its a 200g 8footer... you are gonna want to run 4-6 bulbs per side.(8-12 total) to house some higher level plants.. the watt/gallon rule is too outdated and not effective for comparing newer g4 and t5ho...and esp leds. Unfortunately running 2 bulbs per side isn't gonna get you the penetration you need to grow plants

 

[jetajockey]

here's a chart that will help you figure out what kind of lighting you'll need.
PAR vs Distance, T5, T12, PC - Updated Charts

Running 2 bulbs per side isn't going to be a penetration issue as much as not having an even spread across the width of the tank. That can be remedied by placing the fixture higher up if you have enough extra light intensity to compensate with.

A good even coverage and decent PAR are most important. And even if you don't manage to get even coverage and have dark spots, you'll just have issues with the parts that are shaded.


6700k is the 'daylight' area for bulbs, although different manufacturers have different ideas of what that means, so sometimes one will look different than others. I like the ~6000k lights, they have a slight warmth to them, while 10000ks have an operating room feel to them. A lot of people will mix the two to get a nice balance of light.

I wouldn't cheap out on the fixture for a large tank like that, spend the extra and get a quality fixture with good reflectors and bulbs. It would look a little weird if you don't have a canopy covering it, but you could use 1 4ft and 1 3ft fixture to get a better fit over the top of the tank.