What level is your phosphate at? It sounds like you need to either increase the amount of phosban and/or change it more often to get your phosphate level down below 0.03.
If your nitrate is fine, then it sounds like you do not need to dose vodak. If they are high, then dosing vodka will help to bring the nitrate down.
Red slime is cyanobacteria in most cases. Fighting bacterial problems is more difficult than algae type problems, because cyanobacteria are able to grab their needed phosphate & nitrogen directly from organic sources. Reducing your nitrate and phosphate levels to zero when using standard hobby grade test kits will help though.
Here is a copy of what Boomer recommends when fighting a cyanobacteria:
"Some added thoughts from over the years from many
The only known fish to eat Cyano is Amblygobius stethophthalmus and it needs to be the real one not its close relative that is often Mis-ID with it.
A 2- 3 month scheme
1. Water changes. 25% weekly.
2. Bare bottom refugium only for cheato nutrient export and not for critters.
3. Siphon, sump, refugium, etc. every week during water change and clean all filter you have.
4. Blow off all the Cyano and settled stuff you can so it can be siphoned off.
5. Clean out skimmer and cup every week.
6. Carbon, 1 cup per 50 gallons / 2 wks. Try to use ROX
7. GFO -HC , change every month.
8. Purigen, every month
9. Soak frozen food in RO/DI and discard water before use. This is especially true for brine shrimp. Matter of fact I use to pour off the water, and then fill it back up, to repeat it until there was only whole brine shrimp in the container.
10. Read what is in the food and look for things low in phosphates.
11. Keep the pH in the very low 8's or very high 7's, as Cyano will out compete other algae's in higher pH water.
12. The # 1 limiting nutrient for Cyano is N, not P based on studies in various microbiology texts.
13. During these water changes and blowing stuff off and siphoning it up run a Diatom filter with a second cake of PAC (Powdered activated carbon)."
14. Increase water flow where Cyano are growing, as they do not like high currents.
15. Shutting of all lights, almost total darkness for 48 hr. every few days.
Last resort is Chemi-Clean by Boyd.
99.9 % of the time if nothing eats it and it looks like yours it is Cyano.
