MH lighting for 125 and 180 gallon tanks

["Steven Pituch" <spituch at ev1_net>]

I would like to thank everyone who replied off-list and through this list to
my question about tank sizes.  I am currently considering getting either a
125 gallon (72x18x22) or 180 gallon (72x24x24) tank.  If I go with the 180 I
will cetrtainly build the stand lower than the stand for my 75 gallon
Oceanic as the 180 is about 2.5 inchs taller than my 75, and I can just
barely get around the 75.  My next question is about lighting.

I have read info written by several respected members of this list that
three 175 MH pendants are a good combo for a 125 gallon open-top tank.  You
can even get by with two pendants.  I happen to have two Hamilton 175W
pendants, and was considering buying a third one to use if I buy the 180
gallon tank.  Hamilton's recommendations on their web page are on the
border.  Under the bulbs section, they mention 175 W MH is good up to 24
inch depth, and mention 250 W MH is good for 24 inch depths and greater.  I
don't want to be aching later for more light, but would like to reuse the
pendants I have.  They work great with the 21.5 inch depth of my 75 gallon
tank.  Any suggestions?

Also, does anyone on the list own a 180 gallon tank made by All-Glass
Aquarium Company, Inc?  If so, can you measure the actual dimensions of the
outside frame to an eigth inch?  I don't know if the nominal dimensions
(72x24x24) are to the outside of the glass, or the outside of the frame.  I
always thought the manufacturer's posted dimensions were to the outside of
the glass, but Oceanic says the dimensions for my 75 gallon are
(48.5x18.5x21.5) and that's to the outside of the frame.  I need it to
design the base.

Thanks in advance,

Steve Pituch