Re:90 gallon plant tank, suggestions?

> The rule with HO's and VHO's is that they put out 2x and 3x more light,
> and they burn out 2x and 3x faster, respectively.  In theory, you'd have
> to change your VHO's every 2 months (that is, if you're a die-hard plant
> fanatic who'd change their NO bulbs every 6 months, unlike the rest of us
> droogs who just wait until something burns out in one of the other tanks
> before swapping tubes and buying new ones).

Eric, this is not necessarily correct.  I think the key is what type of
ballast is used with the bulbs.  My set up uses the IceCap electronic
ballast.  In this configuration I've had my VHO Aquasuns running 10-11
hours a day for well over a year without failure.  This weekend I did
replaced all four lamps because my plant growth had slowed.  I see no
reason why anyone would need to replace a VHO bulb but once a year and I
know others who have also indicated the same experience.

I have no experience using VHO's with tar ballasts but from everything I've
read that is not something you would ever want to do.  With the IceCap, the
bulbs burn no warmer than NO flourescents, and the ballast does not warm up
at all.  With my canopy, MH lighting would have required cutting to
accommodate cooling.

Even though my Aquasuns were over a year old they still burn plenty bright
(brighter than any NO flourescent).  I did notice that when I compared the
new Aquasuns to the old ones (burning them side by side) that the old ones
looked yellowish compared to the new bulbs.  The new bulbs looked blue
compared to the old bulbs but next to a VHO Actinic White, the AquaSun
looked very white.  

For the lighting experts out there, do phosphors wear out?  Does the output
wavelength change drastically over the life of the bulb?

I'll admit that the operational cost of a VHO lighting system is much
higher than NO bulbs, but for someone wanting to get the most light
intensity in a small amount of space (without moving to MH), VHO is the way
to go.