A year ago I started a 75g planted tank. After doing some sporadic reading I threw a few plants in over some fluorite and gravel and filled it up with water. I found a cheap Eheim 2213 and for some reason decided it was big enough for this tank.
Since I knew that more light was better I bought a couple fixtures from ebay. I swapped out the actinics and ended up with 8 x 54 watt 4 foot T-5 bulbs. This was great because I no longer needed any other lights in my basement.
I cycled the tank with some filter media from another tank. Once my nitrites were down I slowly built up a fish population, mainly Rainbows. By this time my plants were growing well but the old leaves were dying off quickly. I figured it was a deficiency of some sort and so I began adding pretty much everything seachem makes, with the exception of trace. That didn't help, so I decided to add CO2.
Nobody around here sells CO2 tanks for a good price though so I went with DIY. Having four pop bottles bubbling away might have helped with the dying leaves until my cat decided to knock them over. I came home one day to a white tank filled with gasping fish. There was enough pressure in the bottles to pump the alcoholic swill up into the tank. After a lot of water changing everything was alright. I lost a couple of SAEs but the big Rainbows and even the little Furcatas and Threadfins all survived. Even after the massive waterchanges the plants were all covered in a yeasty mess. Once the Pleco had that all cleaned up the tank looked okay again. I gave up on DIY and pieced together a pressurised system, only to learn the hard way that needle valves are good and end of tank dumps are bad. When my pH test couldn't figure out just how low my pH had gone I did more massive water changes. No fish died this time, somehow. That's when I gave up on CO2 altogether.
Anyway, even with some 432 watts of T-5 light on this tank, sitting about 2 inches over the water, I don't get more algae than my pleco can handle. I don't really do regular waterchanges but I do fairly often add fertilizers. I did double up the filtration at least.
I'm just trying to say that even if you can't afford/be bothered with a CO2 setup, your planted tank can still do well. The plants bubble oxygen, multiply, and finally get so crowded that they need to grow out of the water.
Or maybe it's just a fluke.