Well, I gave ecobak a try and my experience has mostly been negative.
To start with I don't use gfo and my nitrates started at zero on api and phosphates are zero on salifert. I realize neither of these test kits are terribly accurate and I had a bit of green turf algae so I figured I had a decent level of both phosphate and nitrate to work with. Although I have not been able to keep macro algae alive for the past two years or so, still not sure why. I have 65 florescent watts over my refugium (supposed to be equal to like 500 watts of incadescent) so light shouldn't be an issue.
So three months ago I put in a batch of ecobak and didn't really see much of a change (a bit more skim and it is more stinky). I had the outflow of the pellets directed directly at the input the skimmer. About three weeks ago I rearanged my sump a bit and decided to move the outflow into the refugium area. I figured it wouldn't make *that* big of a difference.
I was wrong, within 48 hours I lost a *huge* rose millepora (rtn) and I had cyano on everything. This is my first sps/acro coral loss since starting the hobby. Up until this point I had never had any issues with cyano in my tank either (other than the initial cycle many years ago).
The only positive, I guess, is that some hydno I had low in the tank greened up a bit (usually it runs kinda pale) and one other green acro is slightly more green now.