Planting a pre-existing tropical community tank

[Paintcraze]

It is my understanding that the WPG guidelines do not apply to T5 lighting and that dual T5HOs will yield medium to high lighting over most tanks. Am I incorrect?

[KevinVA]

That all depends. The reason T5HO is so popular, is because you gain more wattage with a smaller bulb. In essence, the rated wattage on your bulb will be accurate. So, for the same 22" long T5HO bulb you have that's rated for 24w would have been rated at 14w as a T5NO. Not the same wattage, thus not the same WPG rating. In a 37gal tank, a dual-bulb T5HO 24" fixture would yield 48w, equating to 1.3wpg. The same tank, using a dual-bulb T5NO 24" fixture would yield 28w, equating to .75wpg. The T5HO fixture, depending on what you're using it for, is nearly twice as efficient.

T8s used to be the more popular bulb to use, because T5s couldn't produce the same light yield as the T8s, and the wattage for the T8s were greater. Technology has changed this. The trade off is the spread. T5s are more concentrated than T8s, so you'll need to utilize more T5 bulbs to cover a larger surface area, than T8s.

[talldutchie]

And the only thing you forget is that you can play a bit with reflectors. Good story!

[KevinVA]

Thanks dutchie and good point. =]