You know what I would do.......and I HAVE done this before.......
I would take everything out of that tank...plants included (put them in a bucket of water)...and do a MAJOR gravel vac...remove ALL the water..(yep, I said ALL)..and scrub and bleach all the decorations (treating with dechlorinator afterwards). (DON'T put bleach in the tank!!) Scrub down the sides of the tank before you remove all the water so that most of the algae you scrub off goes out with the water.
As far as the plants in the bucket....hhmm....because you want to get the algae off of them.........perhaps removing the leaves and parts of the plants that are the most effected...I don't know what removing all the leaves would do to them, but it might be worth the risk, I don't know. ( I hate bare plantless tanks myself and havn't been able to take this drastic measure yet myself, but my issue isn't quite as bad as yours)
You want plants in that tank that suck up nitrates and phosphates...fast growing stem plants, java fern, anacharis, water sprite....and FILL that tank to capacity with them. You'll need to get a better CO2 system and enough light for the plants to encourage good growth.
Wow....LOL.....I don't even know if this advice is any good or not !!! So I'll just stop here and advise again about heading over to the "Aquatic Plants" section of this forum. Tom Barr is the master plant man there ! I bet this one grabs his attention !
Take heart there fella...there is a solution and I'm glad you can be light hearted about it...lol....I know how frustrating that sort of thing is.
All the best.....when you get that all straightened out...(I'm sure you will)...how bout some before and after pics ? !
