What is this?

[muddywaters]

I had a coral that became overwhelmed with this green stuff. I pulled some off today to see if the coral was still under there. Is this algae of some kind?

 

[Jay Hemdal Verified Community Expert]

I had a coral that became overwhelmed with this green stuff. I pulled some off today to see if the coral was still under there. Is this algae of some kind?

Looks like Ulva, sea lettuce, a type of algae.....

 

[keagan]

What are your parameters? I don't know about tropical Ulva but temperate species tend to like a fair amount of phosphate normally they're found in intertidal areas and estuaries that have higher nutrients than an oligotrophic tropical reef. Although mabey tropical species are different.

 

[muddywaters]

My nitrates are good- 5 or so. Alk, Mg & Ca are good- Alk was a little low. I haven't tested Phosphate. I figured if nitrates were good, phosphate would be too. Is that a bad assumption?

 

[Privateye]

There's plenty of Ulva in Florida (at least a couple of species) so the temp of a reef tank would be fine to grow it.

IME it's pretty easy to keep back with manual removal. Herbivores tend to like it too. The tropical one that's given me more trouble is Ulva intestinalis (formerly Enteromorpha) but it's not awful. And that's not what you have!

 

[keagan]

My nitrates are good- 5 or so. Alk, Mg & Ca are good- Alk was a little low. I haven't tested Phosphate. I figured if nitrates were good, phosphate would be too. Is that a bad assumption?

It's a reasonable assumption, but nitrate and phosphate don't always rise and fall together. A tank can have very low nitrate while phosphate remains elevated (or vice versa) because they're added, consumed, and removed through different processes. I only know about temperate species of Ulva so mabey tropical species like cleaner water (I have literally zero experience with tropical species that's why I keep saying that). It's worthwhile testing phosphate regardless.

 

[muddywaters]

Well, glad it's not something destructive. I am new to reefs so just seeing this stuff. I know all about the different freshwater algae LOL- more experience than I'd like- but this was so weird looking - thanks for your help!