Optimum light level for planted tank

 After going through the recommended materials for a "plant grower" I'm
surprised by the diversity of opinions on the optimum light level.
I'm mostly refering here to "high-tech" tanks ie. with CO2 and fertilizer 
 So, let me waste some bandwidth to quickly summarize what's
- *.aquaria: 2-4 W/gallon; innacurate IMO, eg. 2W of Vita-Lite=85.5
lumens while 2W of PPUT=138 lumens; so, do we need 2-4W/G of Vita-Lite
W or PPUT W or what kind of "W"?
- Horst&Kipper (Dupla): 30-50 lumen/l(113-190 lumen/G)  
- Scheurmann: .5W/l(1.9W/G) regular fluorescent tubes or
              .3W/l(1.1W/G) Lumilux fluorescent tubes. BTW, did
anybody see these Lumilux tubes that are also mentioned by Dupla to
have a 95 lumen/W output ? Are they available only in Europe ?
- Dennerle: here we have a nr. of tubes/tank width table correlated
with tank depth, for a tank 50 cm(20") deep we would need the tubes to 
be spaced 15 cm apart to grow any plant, so for a 12" wide tank we need 
2 tubes 2-4"shorter than the tank, for 18" wide we need 3. The tubes are
said to have a lumen output of 50-80 lumen/W. This is a surprising
recommendation, quite a bit below the light level recommended by the
- Amano: As high as 2W/l(7.5W/G !) for small tanks to as low as .2W/l 
(.75W/G) in the big tanks. Since the other parameters are pretty much
similar (CO2,fertilization) throughout the tanks, did anybody figure
out why ? (this was mentioned here before)

 I would like to hear as many opinions/experiences with the above
recommendations or other ones. Maybe we can start on thread on this.

 Didi Soichin
 didi at wwnet_com
 Westland, MI, USA