I would think no, but in case I'm way off, what kind of "carbon supplement" are you thinking of? From what I understand, anything other than injected CO2 gas (compressed or natural via yeast such as Nutrafin system) is a waste of money. I've seen tablets that you can add that will release CO2, but for what these are worth in a matter of a couple weeks you are better off buying something like a Nutrafin Natural CO2 system. I've had absolutely no regrets with mine, in fact I'm going to be buying a couple more of them soon; one for my newly planted 10G and an extra to double the CO2 on my 30G jungle with a solar system above it). Here's a link for the Nutrafin Natural CO2 System at Big Al's. Well worth it in my oppinon.
