Here's what will change: nitrate and phosphate will get used up faster, as well as traces. Everything's gettin kicked up a notch.
Can you tell me the dimensions of the tank? if its a shallower tank, your light will penetrate more. If its taller, then less light hits the bottom. This mainly affects foreground plant options. Crypts will work great in your setup. Get a variety, pretty easy to find red/bronze, and green for a nice mixture of color.
You'll have to test more frequently (maybe, 3 times a week) for nitrate, and phosphate. Keep those at 15ppm and 1.0ppm respectively. Use the pH/Kh
chart to test CO2
levels...those are likely going to drop when light increases...so you may need to add a second DIY
bottle, and just use a T connector to run it to the same diffuser.
The change won't be that drastic...not like if you were going to 3wpg of PC
lighting. If you do get algae, just identify the cause (which nutrient is out of balance), correct it slowly, and be patient. If you do get algae, its only temporary.
You might wanna pick up bulk ferts from www.gregwatson.com
if you don't have sources of potassium. However your tank doesn't look heavily stocked, so you might end up dosing enough KNO3 to cover your potassium needs.
Plantex CSM with extra iron might be worth picking up. Do you have a trace fert now?