A very interesting thread with a wide variety of opinions! It's no wonder this is such a frustrating topic for so many reefers. Going to add my two cents worth so sorry in advance for the lengthy post...
I'll share that I'm battling the red slime as well. I have a large tank that I've basically ignored for the past year and a half. I have a blue tang, pair of clowns, flame hawk, and green chromis damsel currently in the tank along with a dozen SPS and LPS corals. My real problems began when I lost a large naso tang. He wedged himself under some of the rockwork in a place that I physically couldn't get to without literally tearing out most of my rock. I decided to set my H&S skimmer to pull wetter skimmate and hoped for the best. The red slime began showing up soon after. I got frustrated and due to changes in work/life/etc, I got to a point where I couldn't focus as much on my tank.
Fast forward about 18 months... I've kept up with the most basic maintenance thanks to how I had the tank set up... I have a Spectrapure RO/DI system that I've kept up with as far as replacing filters and a Tunze Osmolator that I use to keep the water level in the tank constant. I have a 40gal top off reservoir that I fill up about once a week at which time I would toss in some flake or pellet food that I'd used before the outbreak. I quit using frozen foods during this time altogether. I'd clean the skimmer cup maybe once every other week.
In those 18 months, I've lost 2 green chromis damsels and a sailfin blenny also. I also had a couple of SPS corals overgrown by cyano. However, all of my acan colonies along with a galaxea colony have been thriving. I've also had a couple of encrusting monti's that have done a good job of not only fighting back the cyano but growing and expanding. Conversely, a birds nest colony and a ORA blue tort weren't as successful and they ended up being overrun by cyano.
So with that brief history out of the way... I've decided to try and fight the cyano and regain control of my tank. I don't think that overfeeding is necessarily the problem with cyano but nutrient sequestering is. The natural decay of organisms in the tank has contributed dissolved organics that the cyano are using before it can be skimmed out. However, I haven't lost a fish in at least 6 months so I'd argue that the net addition of nutrients from fish loss should be offset by skimming. Also, the three 250W XM10k bulbs I used were replaced with new bulbs of the same type shortly after the cyano outbreak began. They are currently about 15months old and I have another set of new bulbs in hand but I haven't yet switched them out as the color output is still good (at least good to look at).
So overfeeding isn't the culprit... and I don't feel it's the lights. I've settled on the nutrient export approach to solve this. I agree with one of the theories earlier about bacterial competition for nutrient uptake. At least, that's the theory I'm going to try and focus on. The tank is well established and low free nutrient (0 nitrate [API], 0 phosphate [Salifert]). I'm concerned about using red slime remover alone because killing off the cyano will only release the nutrients back into the water column. I need to have something that can take up those nutrients before the cyano can recover. I have a pair of TLF phosban reactors that I just added fresh GFO to but that will still leave nitrates behind. The skimmer has been cleaned out and is ready to roll (H&S A300 is a monster for the tank size I have) and after reading some vodka dosing threads, I like the idea of bacteria out-competing the cyano and other algae for N and P and getting pulled out of the water column by skimming. I'm 4 days in to a vodka dosing regimen combined with daily dosing of Brightwell's MB7 to help seed bacterial colonies. I'm going to siphon off as much of the cyano as I can later today and see how things proceed. If in a week the cyano is still coming back, I plan on dosing once with red slime remover with the thought that by then I should have a solid bacterial presence in the tank to help consume the nutrients from the cyano die off.
It's too soon to tell if the vodka dosing is making that much of a difference but now that summer boating season and my son's football season is complete (I coach), I will have plenty of time to sit back and observe. I plan on taking things slowly and I'll admit that my long winded post is an extra incentive to keep at this and to keep coming back to RC so I can share the positive/negative experiences with my fight against cyano.
Good luck all... and happy reefing!
-Chad