Yet another identification post - dyno or diatoms?

[zielit]

I have set up that tank over a year ago, around second month that thing showed up.

I thought OK diatoms, normal thing. This is 65g with canister filter so water quality wasn't that good. The brown stuff didn't affected fish or corals (mixed but mostly softies) over the time I kept adding OTR skimmer (for 50g) and another bigger canister filter (eheim pro 4+ 350). Corals loved that, but it didn't help with diatoms/dino. Because I was using tap water I though OK I'm adding most likely silicates with it so few (around 6) weeks back I installed my new RODI and added banded goby for sand sifting. Since then I rarely see it on the glass but sand issue didn't budge. Unfortunately looks like I'll also loose goby today (could be unrelated) hence a little scare that it is not diatoms after all.

2 microscope pics for identification help below.

 

[vetteguy53081]

Looks like diatoms

 

[Hallowhead]

I need to bite the bullet and get a microscope to identify algae.

 

[taricha]

2 microscope pics for identification help below.

unfortunately, it's a type of dino. likely prorocentrum

 

[zielit]

Update: need some serious help on these. I tried 5 day black out followed by 2 week no water changes with dosing phosphates which were always zero or near zero in my tank. It might have slow it down a bit but didn't eradicate them. My NO3 jumped up to 20ppm and corals really looked very unhappy so I couldn't keep that going any longer, slowly started adding back white spectrum light, changed most of the substrate with live sand and added live nitrifying bacteria as well (dosing it with turkey buster over the substrate) hoping it will out-compete the dinos. Week later guess what - motherf$%& are back. :mad: