Startup Problems

My Plant tank is 6 weeks old.  And my plants are not dieing , but not really 
growing that well either.
How 'bout some advice you experts.  Any Tips are GREATLY appreciated.

Given :
90g plant tank (24" tall)
Tetra C02
latetrite in lower 2/3 of substrate
liquid fertilizer @ day
4 40w full spectrum bulbs (in homemade shop Home Depot hoods)
NO Substrate heating :(
2 black mollies
Ph 7.2, 78degrees, hard water

My plants are very green on top, but all the leaves rot off on the lower 2/3 
of my plants.
Roots seem to sprout out all up and down the stems.
Water is still very cloudy, no vigirous algae growth.
My tank doesn't seem very bright, but then it is cloudy, and all the tanks i 
see on the Internet don't look very bright to me either.

What do you suppose I am doing wrong?

John Coggeshall

P.S. Fish Auction in Houston, Texas tomorrow ..... whoooo whoooo (Homer 
Simpson sound), "Im there dude" (Butthead comment)