I have an empty 90 gallon tank (48x18x24) and I've decided to go with a planted tank. It'll be low tech, just dosing TNC carbon and Seachem Flourish. My problem is that the tank only has two 30 watt T8 bulbs which leaves me at 0.6 WPG. The tank even looks really dull. I just picked up a starter unit with two 40 watt T8 bulbs which combined with mine would take me to 1.5 WPG. Is this enough for a low tech tank? Will only be keeping amazon swords and crypts.