I don't know about cooking rocks, but I believe the vodka dosing is to help the beneficial bacteria consume nitrates or something like that, which in turn helps reduce algae.
I WAS dosing vodka, then I went on vacation and forgot to continue dosing it. Very small amounts in my 58g+20g, like 1.5 ml per night.
I do think that my skimmer really went to work once I started, so looks like it's pulling out a whole lot more than before the vodka ... unless it's just skimming out the vodka!
I used the cheapest vodka I could find... lik $6 at Longs Drugstore. In fact it was "Longs Drugtore" BRAND vodka. I feel sorry for whoever sits around drinking drugstore vodka, but I guess for mixed drinks and frat houses, it's a steal! I still have $5.98 worth of that vodka! I mean, it's a 750 ml bottle and I used it for a few weeks!
I think the vodka is worth trying. I may start it up again, thought I just put a CA Rx on the tank and don't want to make more changes for at least a few weeks. It's a bit tedious dosing every night!
V