# What is this yuck?



## cininohio (Jan 13, 2016)

I have no idea what this is. It started about a month ago and has taken over everything. I boiled my large rocks today, soaked them in bleach water, tried to scrub it off with a brush and it does not come off. I have no idea what it is. It's red and hard to scrape off of the glass also. I had to throw away 2 large anubias plants as it would not come off. I tried excel, bleach soak, peroxide. Any ideas? It is out of control and I have no idea how to get rid of it. Thanks in advance.


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## kgbudge (Feb 8, 2019)

First thought: Potassium deficiency.

But I'm fairly new at this and will be interested to hear what others thing.


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## cininohio (Jan 13, 2016)

Not sure why a potassium def would grow a red crust all over rocks and the glass. Never heard of that happening. Any other ideas?


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## kgbudge (Feb 8, 2019)

Ah, I understand now. The second photo looked like brown dead patches in the leaves, but it's actually a red crust. Perhaps red slime algae, which is actually a form of blue-green algae?


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## Discusluv (Dec 24, 2017)

Oh wow! Thats weird.


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## cininohio (Jan 13, 2016)

I know. It is stressing me out. I know my nitrates are high, but they always are. I did a 30% water change today and plan another one tomorrow. All the other parameters are fine. My tank is about 3.5 years old and I have never had algae or any issues. I only use leafzone every other week or so when I do a water change. I have 2 angelfish, a white cloud and 2 cory's. That's it. Fed every other day. Hope somebody has seen this and can identify it for me.


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## Mike A. (Jan 6, 2018)

That is odd. I've seen red algae/bacteria that look like that in marine tanks but never in fresh.

See here:

http://oi59.tinypic.com/33durr5.jpg
https://www.plantedtank.net/forums/23-algae/765473-red-spot-algae.html

Very similar pic here but no help in the thread:









https://www.aquariumforum.com/f5/red-spots-my-tank-14923.html

Another:
https://www.karrgalaxy.com/2017/10/red-algae-problems/


Hildenbrandia sp. seems like the best guess from what I see.


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## ranger8787 (Oct 20, 2020)

I know older thread but figured I would give a shot....You ever determine exactly what algae this is? I have had in my freshwater planted tank for years and can't get rid of. Any luck determining what it is and how to get rid of? Seems to be outside of the normal algae and can't find any info on it.

Thanks


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## rjk8619 (12 mo ago)

cininohio said:


> I know. It is stressing me out. I know my nitrates are high, but they always are. I did a 30% water change today and plan another one tomorrow. All the other parameters are fine. My tank is about 3.5 years old and I have never had algae or any issues. I only use leafzone every other week or so when I do a water change. I have 2 angelfish, a white cloud and 2 cory's. That's it. Fed every other day. Hope somebody has seen this and can identify it for me.


Did you ever find out what this was ? I have the same issue in my planted tank. Any help would be appreciated.


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## itsdirk (Dec 16, 2021)

Algae. This is why I like so called “pest snails”. They devour it.


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## rjk8619 (12 mo ago)

Yah it's alge. But what type ? I've had tanks for 60 years and have seen all types of alge but not like this. The tank in question has several mystery snails.


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## itsdirk (Dec 16, 2021)

No clue. Had it. Got snails on accident. They ate all of it. *shrug

Pleco would eat it to if he could reach it.


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## Yabig Mastiffs (11 mo ago)

cininohio said:


> I have no idea what this is. It started about a month ago and has taken over everything. I boiled my large rocks today, soaked them in bleach water, tried to scrub it off with a brush and it does not come off. I have no idea what it is. It's red and hard to scrape off of the glass also. I had to throw away 2 large anubias plants as it would not come off. I tried excel, bleach soak, peroxide. Any ideas? It is out of control and I have no idea how to get rid of it. Thanks in advance.


I have the exact same thing. Only thing in the tank for months now (45 gallons) is one tetra, a large pleco and several snails. I'm about to re-do my tank but this stuff is just evil.


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## Pencil2Print (Nov 20, 2009)

I was reading this on another (Reef) forum and speculations say its from lack of nitrates in the water. A form of red algae though it looks like Coraline algae in the reef tank.

Some people think using marine salt in the tank (for ciclids or brakish water) encourages this algae to grow too which makes sense since it's more of a marine thing

https://reefs.com/discovery-of-first-freshwater-coralline-algae/ a page i found too


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