That is a good light level for a 55 gallon tank. It will give you low medium light at the substrate. With CO2 you can grow most plants very well with that, although at a slow growth rate. You don't need to use high CO2 concentrations in the water with low medium light, so DIY CO2 can work fine, but you do need to use two bottles, changing one bottle per week, to avoid having large variations in CO2 level which can encourage algae to grow. It is also best to change the bottle after the lights go out at night, so the CO2 production can build back up before the lights come back on.