What are these?

[snowlynx]

I bought some Tonga rock from BRS. I rinsed them in very hot tap then cold tap water.

My tank is cycled but now I seeing these little floating brown strands, what
are they? Threat or harmless? Do they keep growing?

Scary how some organisms just don't die! lol

 

[Ron Reefman]

It's really hard to say based on the photo.

Most hairy algae isn't too bothered by hot or cold water, even for several minutes.

If you want it cleaned off and gone you will need to do something more drastic. Hydrogen peroxide (the 3% solution for human use) will help, but I think it's less effective than pure white vinegar or a mild solution of muriatic acid. A one gallon bottle of muriatic acid is about $10 to $15 and will make 10+ gallons of solution that is a bit stronger than vinegar. Whatever you use, rinse it thoroughly before you put it back in the tank.

 

[snowlynx]

It's glued to the other rocks, can't easily remove it :-(

So if it keeps growing longer, it can spread?

I will look up hairy algae

Thanks

 

[mcgyvr]

I really can't tell what I'm looking at in the pictures.. They just aren't that focused/detailed..

But in general there is tons of "fun" life that you can find once your tank gets going and even more so when/if you get corals as loads of "hitchhikers" will come in on them..

This is a good site with many of the common "creatures"..
Give it a quick skim and bookmark it for your future use..
https://www.lionfishlair.com/hitchhikers-guide/

 

[Crooked Reef]

Are they kind of clear, hard and break off if you try? If so they are sharp. I have some on my rocks. It was some kind of tube worm and that is what is left after they die.