Lyngbya infestation

[Riclat]

I've got a bad problem with a dark green hair algae. Over the past 6-8 weeks I've cut back on feeding my fish to every other day, added a small mespilla urchin, an elysia slug, several emerald crabs and have lots of blue-leg hermits and snails. Nothing seems to eat this algae. I also use RO water, C Balance A+B, and Kalkwasser for top off.

I originally thought the algae was derbesia, but am not thinking its lyngbya. It's very dark green and form tufts that quickly grow. I've scrubbed my rocks several times but it starts coming back within 4-5 days.

Any ideas how to get rid of it? Will a diadima urchin eat it? Will increasing alkalinity hellp? What causes this type of algae?

Here are my measurements:
KH/Alk 7.2/2.57
Calcium 335
Ammonia 0-.25
Nitrite 0
Nitrate 0
Phos. 1.2
pH 8.3
Salinity 1.025

Thanks,
Richard

 

[Opcn]

Mespilia Urchins stick to mostly coraline algea, Diadema urchins should eat just about anything plantish.