Have in mind that the reflectors of the AHSupply provide a narrow beam
of light. I have bought at least 7 of their 2 x 55 set ups and I love
them, but the narrow beam may be a bit of a problem. You can clearly
see how some stem plants first grow to the side to get under the light
and after that they shoot up.
As I hear Kim that owns AHSupply won't sell a bulb that is crappy so
that is another great thing about AHSupply.

2 wpg for a standart 55 is not really high. Some light loving plants
will grow slow and weak until they reach higher and than grow really
well. The same effect is seen if you lower the water level in the 55
standart tank.

I'm just giving you some points to consider.

--Nikolay