Chris,

I would have really preferrefed to run 3 T-5's 10" above the water level. I
may need to reconfigure the ballast to do this . Most T5 ballast run even
numbers of t5 54w bulbs. Maybe you have a better reflector than me because
I have some plants on two T7's (PC) that are not growing well over all.
Others are growing too well. The growth mostly corresponds to their light
requirements.

I am aware of the efficiency gain. T5 are fairly new. I am also going to
switch to growing marine macro algaes in the near future and will need the
extra intensity with one actinic atleast. In the meantime I could raise the
light fixture habging by cables to reduce intensity as needed.

Drew

"Chris_S" wrote in message
...
Thats what I use currently. About 2 watts per gallon is sufficient for
many
plants.

You cannot compare wattages without understanding efficiency. For
example,
a 1W T5 puts out far more light than a 1W T8, and even much more than a
T12.
Generally the smaller the bulb the more efficienct it is. That is because
the plasma is much closer to the phosphers, and the optical thickness of
the
plasma is thinner.

The old rules of thumb about so-and-so watts per gallon started with T12
bulbs, and really does not address true intensity of lumens per gallon,
which is the real intensity parameter that matters.

The T5 biax bulbs (power compact type, etc) are very high efficiency.
They
produce a lot more lumens per watt.

I think my question should have been what is the visual appearance
differance between 55w 6700 K PC bulb and a 54 watt DAYLIGHT T5 bulb?

If you are talking about conventional T5 bulbs vs. the rare earth
tri-phospher bulbs, I would suggest you stay away from the low cost
daylight
bulbs. Their spectrum is very poor and no where near the wide spectrum of
the 6700K bulbs.

I have grown Lotus plants with red leaves clear through the top of the
tank
with my two 55W 6700K bulbs. Grew so fast I could not prune them enough.
I can't imagine needing or wanting more light.

Now if you use the daylight bulbs, then perhaps you may need 4 bulbs and
still not be the same effect. It must all be considered together:
wattage,
efficiency, and spectrum.

Chris.


"Chris_S" wrote in message
...
I've got 2-55W 6700 PC's on my 55G planted FW tank, and that is plenty
of
light. With CO2 the plants grow out of the tank faster than I can
prune
them. Can't imagine needing more light than that, and sometimes I
think
I've got too much light. Some fish don't like so much light.

Chris.


"Beruka" wrote in message
. com...
Would four T5 6500K 54 watts bulbs place 12" over a tank be too
powerfull
for a planted tank?

I use 3 55 watts PC bulbs 3" off the surface with good effects. I
doo
get
thread like algae over the third light occasionally but is very
simple
to
control really.

Thanks

Beruka