Algae exports NO3 and PO4 nutrients at a near balance rate. You can search on RC for the Redfield Ratio. Bacteria, on the other hand, loves N more than P. That is why vodka dosers normally run lots of GFO.
I had a well designed and sized scrubber on a filter feeder tank that was very very heavily fed and it worked great for years. Then I moved and was out of the hobby for a while. In the interim I decided to move up to an NPS tank and read how hard it was to keep down the nutrients so I lost faith in the scrubber. I started my new tank with the same scrubber and it worked great as I steadily fed more and more. At the same time I researched lots of supplemental methods. Even though everything was working great, I added a new feature.
I built a refugium specifically for bacteria. Then I started dosing vodka. In two weeks, I harvested the algae and it didn't grow back because the nutrient load was too low. My nutrient load remained low for a long time but eventually, the PO4 began to rise.
This is an extreme case but I read around and found a thread where vodka users were also dosing NO3. I bought some poison (stump remover from Lowe's) and started dosing it. Pretty soon my scrubber started growing algae and my PO4 started to come back down.
So "¦you can dose vodka but go very slowly. Don't let it out compete with the scrubber or it will not work at its best.
