Rob, have you tried macroalgae to compete for whatever it is thats feeding that growth? There are a lot of differing opinions about its use here, but I have found that its really good at controlling problem algae. I know its just a symptom treatment, but it may help you hang on long enough to solve the cause.Also take out any phosphates or silicates that may be leaching into the system. Also hermits, loads of hermits... also controvertial, but I have found that they have decimated any available hair algae in my system... It may be worth a try if you havnt considered it yet, at least it should keep you involved and increase your chance of solving the problem. Sounds like you have battled this a while so you prolly tried these already....Good luck!