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Mysterious red ring stain

tiger15

Member
Joined
14 Mar 2018
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It started on the surface of a clay pot and spread over onto the heater glass and elsewhere like rashes. These red circular rings are smooth to touch and cannot be rubbed away easily. Are they inorganic or biological in nature. What are they.
 

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Coraline algae? I've seen them in reef tanks but not freshwater.
 
Coraline algae? I've seen them in reef tanks but not freshwater.
You may be correct. From my research, there is only one species that lives in freshwater. While it is desirable in reef tank, not in my freshwater tank as the stains are out of place and hard to remove.
 
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Crikey @tiger15 you should be so lucky. It’s very rare. I can understand how it might be a pita if it grows on the glass though. But at least you know your water quality is good 😊
 
If it is indeed Coraline algae, it is a mystery why a rare freshwater form would grow in my dim light, non planted, non dosing tank where no other algae can grow. Coraline algae is loved in a reef tank giving live rock color, but looks dirty staining my heater, glass and ornaments. The stain is permanent on rough surfaces and can only be removed by razer blade on smooth surfaces.
 
Hi all,
If it is indeed Coraline algae,
I think it is an encrusting Red Algae (Rhodophyta), but not the coralline one <"Pneophyllum cetinaensis - Wikipedia">, below.

I think the Coralline Algae (I've never seen the freshwater one) are all more pink, probably because the white calcium carbonate (CaCO3) masking the red pigments.

800px-Pneophyllum_cetinaensis.webp.png

Habitus of Pneophyllum cetinaensis. Holotype (PC0145164) (a). Typically, P. cetinaensis develops as a crust on cobbles and pebbles (b,c). Extensive coverage in a shaded, shallow area in the type locality (d) where most gastropods are overgrown by P. cetinaensis, commonly with reproductive structures (arrow) (e).Uploaded a work by A. Žuljević, S. Kaleb, V. Peña, M. Despalatović, I. Cvitković, O. De Clerck, L. Le Gall, A. Falace, F. Vita, Juan C. Braga & B. Antolić from Figure 2 | Scientific Reports with UploadWizard

cheers Darrel
 
I have many on my rocks in my 15 year old tank. Noticed some spots under my sand substrate too.
Researching more it is called Hildenbrandia Rubra.
 
I have many on my rocks in my 15 year old tank. Noticed some spots under my sand substrate too.
Researching more it is called Hildenbrandia Rubra.
According to Wikepedia, rubra is a marine species. Its the other freshwater Hildenbrandia species. It said that it can tolerate severe desiccation. I just returned a stained flower pots after months of drying and curious to l see if the algae will revive.

The freshwater species H. rivularis[6] and H. angularis[7] seems to form a clade,[10] and require an alkaline pH and hard water, preferring clean water.[11] Unlike most other freshwater red algae (which prefer running water), H. rivularis prefers still water, particularly shady lakes or ponds.[11] H. rubra and other marine species are found in brackish waters, but freshwater / gemma-bearing species cannot tolerate even moderate salinities.[12] The genus is often found in a symbiotic partnership with fungi.[13] Hildenbrandia has a remarkable tolerance to stresses including extreme temperatures, desiccation, and Ultra-violet light; it can be up and photosynthesizing near full capacity just minutes after being cooled to −17 °C or subjected to extreme salinities.[14]

linities.[14]
 
Yes correct. I think I just copied the name and posted :)
The genus is correct.
 
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