[Genetics]

Aaron, I didn't see the type of skimmer you are using previously and now. When looking at the skimmer previously did you notice an increase in skimmate when dosing vodka? Second, your phosphate were rather high and nitrates were low. Some species of cyano bacteria have the ability to fix nitrogen. As what this means in our hobby I don't know but theoretically if you have a large source of phosphates but nitrates are lacking, cyano has the ability to grow while other bacteria cannot compete as well.

Cutting your lights will starve the cyano of a food source but will come back as a problem later when you resume a normal schedule. Since you are on very large water changes currently, I would suggest syphoning as much cyano as possible from the tank.

With GFO and GAC, it is sometimes easier to run a reactor. This way you can control the flow through the canister so you do not create a large fluctuation in water quality when changing the media. Also, it is easier to remove when you need to change the media out.

What type of aquarium are you running? Is this a fish only? What made you want to start vodka dosing in the first place? Was it a hair algae issue? Nitrates in a fish only tank are not usually a concern unless you have algae. If you are thinking about adding corals then nitrates below 10ppm and phosphates below 0.05ppm are good goals.

Edit: Also, for the time being I would stop with the vodka. You need to establish a baseline with your aquarium. How its doing with the new skimmer. How fast are nitrates and phosphates rising. Vinegar is a useful alternative especially in tanks where cyano is an issue with vodka. However, I would not add this at the moment.

Yes, this hobby is addictive!!! However, the perpetual massive water changes some people undergo drive them out of the hobby!