Algae? diatoms? Dinos?

[N1Space]

Hi all,

My tank is about 6 months old now (20 gallons). This brown stringy, bubbly algae is starting to cover my sandbed, areas of the glass, and some of my coral. I just started noticing this after my 20% bi-weekly water change last weekend.

Thanks In advance.

Phosphates: 0.07
Nitrates: 5

 

[bushdoc]

Hi all,

My tank is about 6 months old now (20 gallons). This brown stringy, bubbly algae is starting to cover my sandbed, areas of the glass, and some of my coral. I just started noticing this after my 20% bi-weekly water change last weekend.

Thanks In advance.

Phosphates: 0.07
Nitrates: 5

Macroscopically it looks unfortunately like Dinos.(slimy with bubbles, brownish) Another clue is your statement that it happened after 20% water change, this probably dropped your phosphates and nitrate significantly and contributed to this event.
For a start stop water changes for a bit and follow many other posts here how to fight it.

 

[sixty_reefer]

Certainly dinoflagellates unfortunately