[eleodes]

yep. this is bad stuff. i had the same experience thinking it was kind of cute in small amounts.

i have a seaweed tank and i introduced some of this (it was unavoidable, i had it all over everything) from an older system. i got my seaweeds growing really well and they have clearly outcompeted this algae: the little tufts that were in there have just been getting smaller and smaller and i can hardly find them anymore.

your seaweed-dedicated refugium should help to knock this stuff down. you might try to do whatever you can to encourage the weeds. i have been dosing nitrate (Flourish Nitrogen) and keeping it at ~5mg/l.