Another thing to look at may be your salinity. I've got an "edible" sea cucumber and a tiger-tail; the edible will climb the glass if my salinity drifts.
Running a small 45g AIO. The tank is fairly new and I was experiencing the typical algae outbreaks. A LFS recommenced sea cucumber and strawberry conch.
The Nori is working so far but I don’t think it’s a long term solution. I will likely return the cucumber.