Chlorodesmis? Derbesia? Bryopsis plumosa or Something else?

[Critter]

Last summer I developed a hair alage outbreak due to lack of flow and high water temps. Since then I've tried jsut about everything anyone has suggested. This is the best picture out of 12 that I took with my camera, sorry.
It grows only on the rock for the most part, it will also grow on snail shells. It is soft to the touch, and pretty well rooted where it is on the rock. I have a yellow tang and had a lawnmower blenny and neither would touch it. No snail nor crab will touch it. Because of this I'm thinking it's Turtle weed. Any resonable guess would be much appreciated. Thanks in advance. If need be I will hire someone to take a better picture :|

http://ckunz.echoes.net/100_2893a.jpg

[piercho]

Not turtle weed or Bryoposis plumosa. I've been calling something nearly identical to yours Derbesia but not sure if that is the correct genus. As a general grouping its what I call a turf algae, and what most reef hobbyists call a hair algae.

Zebrasoma tangs graze soft turfs like this but since yours avoids it I would guess its not very palatable to the tang. Those giant Mexican turbos may do something to this algae, IME they can and will graze soft turfs. But IME they also starve in my tank in a few months. I don't recall if Diadema urchins graze it, but Diadema will get around to grazing most everything with a few exceptions. I'm pretty sure tuxedo urchins won't.

That algae (or something nearly identical) rapidly populated and was the star performer in an algae turf scrubber I ran for close to a year. As far as control in my display, persistant lean conditions did make it go away. A Siganus rabbitfish may have assisted a bit, but I don't think Siganus is any more likely than Zebrasoma to be effective against this one. I still have patches of it pass through the display, such as after I moved the tank or recently when I dramatically increased my feeding.

[Critter]

Thanks for the reply. I'm going to reduce my lights as much as possible. I have a pre-filter on my overflow, which seems the darkest green in the morning, meaning at night lots of this stuff gets into the water. I've replaced my lights, got a bigger skimmer and am now using RO/DI. Because I can't get a nitrate or phosphate reading, in your experience, which of the two would you say is the driving factor or both :\ I have also been growing cheto and drip kalk for some time now.

<a href=showthread.php?s=&postid=9467560#post9467560 target=_blank>Originally posted</a> by piercho
Not turtle weed or Bryoposis plumosa. I've been calling something nearly identical to yours Derbesia but not sure if that is the correct genus. As a general grouping its what I call a turf algae, and what most reef hobbyists call a hair algae.

Zebrasoma tangs graze soft turfs like this but since yours avoids it I would guess its not very palatable to the tang. Those giant Mexican turbos may do something to this algae, IME they can and will graze soft turfs. But IME they also starve in my tank in a few months. I don't recall if Diadema urchins graze it, but Diadema will get around to grazing most everything with a few exceptions. I'm pretty sure tuxedo urchins won't.

That algae (or something nearly identical) rapidly populated and was the star performer in an algae turf scrubber I ran for close to a year. As far as control in my display, persistant lean conditions did make it go away. A Siganus rabbitfish may have assisted a bit, but I don't think Siganus is any more likely than Zebrasoma to be effective against this one. I still have patches of it pass through the display, such as after I moved the tank or recently when I dramatically increased my feeding.

[piercho]

Because I can't get a nitrate or phosphate reading, in your experience, which of the two would you say is the driving factor or both I don't know. Its not unusual to have algae growing below the range that you can pick up readings for nitrate and phosphate on hobby kits. Generally, in SPS reefs control of phosphate by skimming, absorption (iron based media), binding/precipitation (limewater), detritus removal and uptake (refugia plants) is where most people focus their efforts. Its generally assumed that nitrite-nitrate at low levels is not a problem unless its fueling algae growth that threatens coral by overgrowth. Phosphate, on the other hand, inhibits calcification in coral and is always considered "bad".

Keeping carbonate alkalinity a little high may help. Cultivating a robust population of micrograzers may help. There may be a fish grazer that will tackle it but I would think your Zebrasoma tang would be about the best bet. Sprung recommends Elysia spp. sea slugs for Derbesia, an alga that is similar to this one. Diadema (long spine urchin) would probably get around to grazing it. But Diadema grazes the rock down to bare white "bone", something many reefers don't like. Diadema will also tumble over frags and small rocks that are not decently secured.