Algae on sand vs dinos? Microscope images included

[ConsummatePro]

I've been getting this green growth on my sandbed - I can get rid of it temporarily by combing the deeper sand over it, but it grows back the next day and I'm sure it's photosynthetic. Right now it's mostly along the front of the tank where there is less light than the center of the tank - especially since this is a bowfront tank.

I'm pretty convinced its an algae but thought I'd post some images and parameters for feedback, as well as tips anyone has to get rid of it.

The tank is actually > 15 years old previously FOWLR, but now "reef'd" for the last 5 months with mostly LPS and just a few small SPS frags right now. This growth popped up in the last few weeks. There isn't any hair algae or other nuisance algae elsewhere.

A couple months ago I did actually have zero/zero No3/PO4 but after losing a birdsnest I learnt to keep NO3 and PO4 at nonzero levels with increased feeds including Reefroids, however, my current NO3 = 4.6, PO4 = 0.09. I'm currently feeding the fish/tank using a Plank feeder every 2 hours for 10 hours, a mix of flake, freeze dried mysis, plankton, and some small amounts of Reefroids and Reef Chili thrown in to broadcast feed the corals (~1/2 tsp in the whole hopper of the Plank which lasts more than 2 weeks).

Parameters:
Tank: 160 gal bowfront
Lighting: Neptune Sky's x 2 with PAR around 100-150 at the sandbed, closer to 75 at the front of the tank, photoperiod ~13h, Sky Coral Growth 40% intensity, 8 inches off water
Temp: 78.3
pH: 8.1-8.25
No3: 4.6
PO4: 0.09
Salinity: 35.4
Alk: 8.69
Ca 4.47
Mg 1387

Pictures attached (using Sky photographic mode) plus a video of the flow and the best pic I could get out of my cheapo toy microscope. Looks like an algae to me.

Thoughts? Suggestions to rid? It seems weird it grows in the lower light part of the tank vs the brighter part but it definitely grows with the light.

Should I let PO4 drop a bit? I'm thinking of just excluding Reefroids and Reef Chili fromt he Plank hopper and watching PO4.

 

[taricha]

Hey @Dan_P it's those perfect circle algae cells again.
Not the most common thing, but seen it posted a couple of times. My totally uneducated guess is that this is one of the single cell kinds of cyanobacteria. I wouldn't do much of anything about it.

Should I let PO4 drop a bit? I'm thinking of just excluding Reefroids and Reef Chili fromt he Plank hopper and watching PO4

I would do that. Those are particulates that can settle, and looking at your tank, it might be the case that the areas where your food particulates are settling in the light is where you are getting this growth.

 

[ConsummatePro]

Hey @Dan_P it's those perfect circle algae cells again.
Not the most common thing, but seen it posted a couple of times. My totally uneducated guess is that this is one of the single cell kinds of cyanobacteria. I wouldn't do much of anything about it.


I would do that. Those are particulates that can settle, and looking at your tank, it might be the case that the areas where your food particulates are settling in the light is where you are getting this growth.

Thanks! Perhaps I should also try and increase some flow (or change the pattern to be more turbulent) across the front? I was trying to keep a relative slower flow region for those corals that prefer it. Maybe the Bowfront plus the rock work are conspiring to accumulate nutrients.

 

[Dan_P]

Hey @Dan_P it's those perfect circle algae cells again.
Not the most common thing, but seen it posted a couple of times. My totally uneducated guess is that this is one of the single cell kinds of cyanobacteria. I wouldn't do much of anything about it.


I would do that. Those are particulates that can settle, and looking at your tank, it might be the case that the areas where your food particulates are settling in the light is where you are getting this growth.

I wonder if they are more spherical. The coverslip looks like it might have squished them a bit.

I will join you on the cyanobacteria ID. I am used to seeing organelles in algae. These have a rather nondescript homogeneous inside.

 

[ConsummatePro]

I wonder if they are more spherical. The coverslip looks like it might have squished them a bit.

I will join you on the cyanobacteria ID. I am used to seeing organelles in algae. These have a rather nondescript homogeneous inside.

If it’s a cyanobacteria of the green, non slimy type, do you have any advice on control?

It coats one side of the crushed coral sand flake but each covered fleck of sand separates and remains distinct. It’s certainly not slimy, not in sheets, not making strands, trapping or making bubbles or making a film that I can see, so I’ll admit I didn’t think of cyano.

Should I try for another microscope slide ? Maybe without the slide cover? It’s been a long time since I made slides!

 

[Orito]

I had a lot of that, covering everything, didn't bother the corals, but it's ugly, I increased the flow with a gyre and went away, sometimes reappear in small spots and I turkey baste it away

 

[Lavey29]

Does look like minor cyanobacteria to me also. Increase flow in that area, siphon out during water changes. Reduce lights to 6 hours with blue and uv only no whites for few weeks. Tongan nassarius snails or a blenny as other options to sift sand naturally.

 

[Dan_P]

If it’s a cyanobacteria of the green, non slimy type, do you have any advice on control?

It coats one side of the crushed coral sand flake but each covered fleck of sand separates and remains distinct. It’s certainly not slimy, not in sheets, not making strands, trapping or making bubbles or making a film that I can see, so I’ll admit I didn’t think of cyano.

Should I try for another microscope slide ? Maybe without the slide cover? It’s been a long time since I made slides!

No need for another microscope view unless you have the time. Would love to see more.

Sorry, I have no bright ideas on how to make this go awa6.