Hair Algae, a Symptom Rather Than the Problem?

[revhtree Verified Admin]

A recent post by @Hans-Werner in Randy’s Tank and Learn thread inspired this thread.

Usually we see threads about how hair algae or cyano is killing coral but maybe they are a result of the coral already dying?

Could hair algae or cyano be showing up because something else in the tank is dying or breaking down, rather than being the cause of the problem in the first place?

Curious what others think and whether you’ve seen this happen in your own tanks.

 

[Randy Holmes-Farley Verified Community Expert]

I am in the midst of a severe hair algae issue. It's depressing and gives me a new found empathy for those struggling with it.

 

[revhtree Verified Admin]

I am in the midst of a severe hair algae issue. It's depressing and gives me a new found empathy for those struggling with it.

I can tell you that even when it looks like a lost cause, it doesn't have to be!

What type of hair algae eating critters do you have in the tank?

 

[EnterName]

Algae, cyanos and dinos often grow only in specific spots in a tank. For example, I never get algae on rocks or substrate, even though my snails prefer the glass, while a 3D-printed stand for a Homophyllia grows Ulva(ria) all the time. The frag plug that is sitting on it, however, stays clean.
My powerheads grow Ulva(ria) too, and if I clean them with bleach or HCl, they get covered in diatoms until the sea lettuce comes back. I can only assume the harsh flow doesn't allow the right biofilm to establish, so I would have to get them covered in coralline before they stay free of other algae.

@Dan_P pointed me to this "periphyton theory", and so far it's the only explanation I've found for why algae skips certain spots that get exactly the same light and flow. The organisms living mostly unnoticed on our rocks, like coralline algae, diatoms, and biofilms, must have evolved ways to keep themselves free of algae. Otherwise they would eventually starve or get shielded from light and flow.

It also more or less explains the ugly phase and why sometimes "resetting" the periphyton with something like the UV sweeper or by bleaching rocks can help. The only thing I have not figured out yet is how to get the "good periphyton" to grow everywhere

Obviously, this is all just theory, but it can be backed to some extend by the scientific literature.

 

[Subsea]

I can tell you that even when it looks like a lost cause, it doesn't have to be!

What type of hair algae eating critters do you have in the tank?

“What type of hair algae eating critters do you have in the tank?“

Not sure how much the large amphipods eat but they live amongst its matrix.