18 " t5 's ?

[BlueWorldAquatic]

Actually the only fixture I know that is 18" T5 is a current fixture.

For a few dollars more, marineland make a LED fixture that will fit 16"-20" tanks.

I tested the par ratings of both, the Current USA fixture had a rating of 900 at 12", and the LED had about 1000 at the same depth.

Ken - BWA