Macro algae pest

[Jooce01]

Hey all, I set up a tank for my mom this last Christmas, and she loves the macro algae. She has some red grape, some blue ochtodes, and fuchea(sp?). I just came to visit her and she has a ton of small white fuzzy things on her macros that appear to be killing them. There are light patches where the macros are breaking and she claims that the white fuzzies (her name not mine) are what is causing them. An ID and possible fix would be much appreciated, but just an ID would go a long way.

http://img.tapatalk.com/d/13/03/31/ajyzu6yr.jpg

http://img.tapatalk.com/d/13/03/31/mene9esu.jpg

[manfx]

Pineapple sponges maybe, the pictures aren't very clear though but that's my guess. Don't think they are bad. Could be from silica levels in the water imo

[tektite]

They appear to be pineapple sponges. They are not affecting the macroalgae in that way, they are harmless filter feeders. With that kind of damage to the macroalgae, my guess would be that the macros are being nutrient limited and dying off because of that. Most likely either nitrate or phosphate are too low for them. Other things that may be lacking are iron or iodide, or light itself. If she has large amphipods in the tank that come out at night they may be exacerbating the problem as they will eat the macroalgae alive.