microalgae bloom help with ID . potential dinoflagellates? with microscopy images

[Planarium]

Ive been having a small outbreak of a Dinoflagellates like algae. Its brown and looks slimy, and as it gets bigger/ longer it producers a bubble at the tip. It grows very fast and I end up siphoning the visible chunks every few days so it doesn't grow over the corals. It seems to irritate most of the corals upon contact and potentially caused tissue recession in some of the SPS and LPS.

water parameters:
10 gallon mixed reef, no fish
Temp 25-26C (77-78.8F)
salinity 34-35ppt
Alk- 6
Ca-440ppm
Po4- 0.2ppm
NO3-10ppm
10-15% weekly water changes

Video of reef tank showing the brown strands of the microalgae on rocks and around the corals (2 days after siphoning all visible algae).

microscopy images of the algae colony under x40 and x100 lens

The microalgae is 10-15 um in diameter and seems to secrete an extracellular gel like matrix that binds them together. Its comprised of a single microalgae species with some bacteria in the extracellular material. The density of microalgae in the sampled material (the brown slime) is 5x10^6 cells/ml.


Any ID to a genus level would be amazing. It will help me understand how to combat it. Its very frustrating to have to siphon it out every 2 days or so.

Cheers

 

[taricha]

The microalgae is 10-15 um in diameter and seems to secrete an extracellular gel like matrix that binds them together. Its comprised of a single microalgae species with some bacteria in the extracellular material.

This is chrysophytes.
Motionless tiny golden brown spherical cells that embed in a thick gel.
Welcome to the forum!

 

[Dan_P]

This is chrysophytes.
Motionless tiny golden brown spherical cells that in bed in a thick gel.
Welcome to the forum!

Yikes, these things show up en masse in some of my algae cultures, though seemingly at random, not due to anything.

 

[taricha]

Yikes, these things show up en masse in some of my algae cultures, though seemingly at random, not due to anything.

yes, it seems nobody knows anything all that useful about them.

(except they seem susceptible to algaefix.)

 

[Planarium]

This is chrysophytes.
Motionless tiny golden brown spherical cells that embed in a thick gel.
Welcome to the forum!

Thanks!! getting closer to the to species level ID.
Ill look at chrysophytes specific treatments