Help with identification please

[squarereefer]

Many weeks ago I started noticing brown algae on the sand of my established 2.5 year old tank. My phosphates and nitrates have always been low, but I found at that that they had bottomed out at 0. Without a microscope, and looking at images here + the 0 nutrients, and the rapid disappearance at night with resurgence during the lighting period, I made the assumption is that it is a form of dino.

I slowly began raising my nitrate and phosphate though dosing neonitro and feeding more frozen food until I reached and maintained a phosphate level of ~.06 and Nitrates around 10 and reduced lighting intensity but no change so far. I collected some of the algae from the sand in a clear cup of tank water, spun it around to oblivion and placed it in sunlight to find that it quickly regrouped into this:

I slacked off on testing and my phosphate and nitrate crept up a bit further to .17phos and 10 nitrate which I am slowly reducing. At the same time, this algae has spread over all of my rocks and I can't tell if it's the same as what is on the sand or different. Pardon the video, but it captures more clearly on video than photo.

Video link in case embedded video does not work


My Trigger Triton 20 sump has a fuge spot which I have never used since the nutrients in my tank have typically been low. For good measure, when I noticed the phos/nitrate higher than I want, I went ahead and fired up the fuge with a 12v led grow light and some chaeto from my local store. I am seeing a nice PH stabilization, and hopefully will get see a reduction in algae in time.

Can anyone identify what type of algae I might be dealing with on my sand, and even more bothersome, on my rocks?

 

[Subsea]

I viewed your link and am not certain what I see.

Can you include a full tank shot with white light?

The fact that it regrouped after you broke it up, implies it is mobile Dinoflagellets. Consider adding UV sterilizer to assist with eradication.

Nuisance, opportunistic algae’s like Dinoflagellets & Cyanobacteria thrive when competition is eliminated with bottomed out nutrients. Bringing bottomed out nutrients up does not eradicate Dinoflagellets. Consumers & competitors will assist in keeping it in check. Know this about Dinoflagellets, they are a type of phytoplankton and some are food for filter feeders.

 

[squarereefer]

I viewed your link and am not certain what I see.

Can you include a full tank shot with white light?

The fact that it regrouped after you broke it up, implies it is mobile Dinoflagellets. Consider adding UV sterilizer to assist with eradication.

Nuisance, opportunistic algae’s like Dinoflagellets & Cyanobacteria thrive when competition is eliminated with bottomed out nutrients. Bringing bottomed out nutrients up does not eradicate Dinoflagellets. Consumers & competitors will assist in keeping it in check. Know this about Dinoflagellets, they are a type of phytoplankton and some are food for filter feeders.

I am embarrassed to post the photo; this is the worst my tank has looked in years. I know it's hard to tell scale from a photo, but the tank in an innovative marine 75 - 36" width. I have an 8-watt Aqua Advantage UV sterilizer running, and the bulb was replaced about 24 months ago. It's possible that the bulb is reaching the end of its life.

 

[Subsea]

2 years is too long for UV lamp life.

 

[squarereefer]

Agreed, so I just ordered a new bulb a few moments ago. I was incorrect on the age; my current bulb was ordered on 10/24/24 and installed shortly thereafter, so it's about 14 months at 24/7 usage. Either way, it looks like a year or so is about it for a UV bulb.