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Re: Opinions on lighting

Dave wrote:

In the very near future i'm going to go from a 55 gallon to a 90 gallon
tank (freshwater).  I've currently got a custom made hood that has
provisons for four 40 watt flourescent bulbs (I'm currently only using
three).  I'm not sure that 160 watts is going to be enough for this size
tank.

I reply:

If you wish to keep the same hood and assuming it will fit on the 90 gallon
tank, you can get just barely enough light for high light plants by changing
your ballasts to 1.28 ballast factor Motorola ballasts and using 32 watt T8
lamps. This will give you about 25% more light than can be obtained with a
standard T12 4 lamp system. To grow high light plants you will probably need
excellent reflectors in order to get enough light in your tank.

Three 55 watt or 2 96 watt PCs would also provide almost exactly the same
amount of light.

To get more light with 4' NO lamps you will have to go with 5 or 6 lamps.
The up side of using 6 lamps is you can still use T12s and there is a wider
selection of lamps available in T12s. The down side is that 6 T12s take up a
lot of space. In any case, I would go with an electronic ballast as this
will save you around 30% on your electrical bill.

Four HO lamps could alo be used but finding suitable lamps is a bit of a
problem, operating costs are higher and setup costs are also higher than NO
lamps.

To get more light in the same space, you can use 4 55 watt PCs or two 55s
and one 96.

All of these systems if using electronic ballasts are pretty economical to
run. The 4 T8s would cost the least to set up and operate mainly because the
T8s cost a small fraction of PCs but also because the T8s are a little more
efficient than the PCs.

Speaking in terms of economics only you should forget about using VHO lamps.

MH lamps are a good choice for open top tanks but it is only recently that
reliable and efficient units are being made in small wattages. I think MHs
are hard to install in a canopy type setup but pendant MHs look great on an
open tank although again, the price is not small.

Wayne