Co2 and ferts aren't really needed in a low light tank(well I should say you need a little bit of trace here and there) I got a little 5 gallon with some camboa, moss and some fissedens that is just beautiful, I dose maybe once every two to three weeks and do a WC every three weeks. My friend has a tank that I set up for him with sunset hygro, camboa and anubias, he never doses and the tank looks awesome!
I also have a high light pressurized tank. My high tech needs a lot of attention with weekly trimmings, EI dosing every day 60% WC every week, I guess what I'm getting at is it all depends on what type of plants you want to keep.
You CAN keep a really nice planted tank with what you have already
BUT if you must have a high light tank do it right.
I would do in this order:
1. Change your substrate to Eco, ADA AS, Flourite, mineralized top soil, whatever nutrient rich substrate you want.
2.
Get a canister filter, look for one that will turn your tank volume at least 5 times over per hour, you can find good deals on craigslist or go with that sun sun Chinese knockoff for the cheap route.
3.Get the Co2 regulator,tank,diffuser/reactor. Milwaukee makes a decent all in one (Regulator/solenoid/bubble counter) for around 80 bucks, Azoo makes one as well in this price range.
If you can afford it go with a high quality reg from Sumo, GLA, Rex Grigg, they are worth every pennie.
Get a 10 pound tank at least for the 72.
4.lastly lights, with your deep tank
go with T5HO, 2X54 should be plenty, you can even retro fit your lights with your existing enclosure.
Oh and yull need dry ferts, Macros shouldn't cost more than ten bucks, I dunno how much Tdurden bought with 75 dollars LOL he should never have to buy ferts for the rest of his life for paying that much
Hope this'll help ya!
