What are these dark spots on my rocks?

[Jasongtr]

Anybody know?

They are hard and cannot be scraped off, is it a starting sign of coralline or something more sinister? Asking as i was going to put these rocks in the sump of a new tank im setting up to eliminate the need to cycle the new tank but i dont want to transfer an issue

 

[Dan_P]

Anybody know?

They are hard and cannot be scraped off, is it a starting sign of coralline or something more sinister? Asking as i was going to put these rocks in the sump of a new tank im setting up to eliminate the need to cycle the new tank but i dont want to transfer an issue

By dark spots, are referring to the colored areas?

 

[Cthulukelele]

This looks like a very recently cycled tank, and I'm assuming you're talking about the brown patches. If so, they're diatoms. They're the first algae to take hold typically when you cycle a tank and a sign things are progressing!

 

[Jasongtr]

By dark spots, are referring to the colored areas?

The dark brown/grey spots

 

[Jasongtr]

This looks like a very recently cycled tank, and I'm assuming you're talking about the brown patches. If so, they're diatoms. They're the first algae to take hold typically when you cycle a tank and a sign things are progressing!

Its 5 months old and ive had diatoms and were not like this

 

[Dan_P]

The dark brown/grey spots

They are just out of focus. Are they soft? Can they come off easily? There are so many life forms in an aquarium, that it can be difficult to tell what they from pictures. Sorry.

 

[Jasongtr]

They are just out of focus. Are they soft? Can they come off easily? There are so many life forms in an aquarium, that it can be difficult to tell what they from pictures. Sorry.

No like i said in the first post hard and cannot be scraped off

 

[Dan_P]

No like i said in the first post hard and cannot be scraped off

Oh, sorry. Coralline is usually pink. Can’t mistake it when it starts to grow.

 

[Jasongtr]

Oh, sorry. Coralline is usually pink. Can’t mistake it when it starts to grow.

Thats what i assumed, pretty sure ive seen somewhere where it started off a darker colour, but maybe not then

 

[Troylee]

Looks like the start of hair algae honestly.

 

[Jasongtr]

Looks like the start of hair algae honestly.

How long does it take to get to this stage would you say, bear in mind as mentioned its hard and wont scrape off

 

[vetteguy53081]

algae and diatom.

 

[Cthulukelele]

How much do you feed your tank/how aggressively do you feed it/what is your fish load? Your rocks and sand are incredibly white to me for somebody at almost 6 months of cycle

 

[Jasongtr]

How much do you feed your tank/how aggressively do you feed it/what is your fish load? Your rocks and sand are incredibly white to me for somebody at almost 6 months of cycle

6x fish, fairly big clean up crew i guess, feed 2/3 times a day frozen and algae wafers 2x a week

 

[Troylee]

How long does it take to get to this stage would you say, bear in mind as mentioned its hard and wont scrape off

It can happen at any time.. my tank is 10 years old and just had a break out.. it normally pops out after an initial cycle also.

 

[Jasongtr]

It can happen at any time.. my tank is 10 years old and just had a break out.. it normally pops out after an initial cycle also.

Fair enough, so i guess if it is what you say then my plans to drop this rock into the sump of the new tank isnt a good idea

 

[Cthulukelele]

Fair enough, so i guess if it is what you say then my plans to drop this rock into the sump of the new tank isnt a good idea

No it'll go away on its own usually. Waxes and wanes. Clean up crews help speed it along

 

[Jasongtr]

No it'll go away on its own usually. Waxes and wanes. Clean up crews help speed it along

Fair enough, since the tank started if not really had any issues with algae etc

 

[Cthulukelele]

Fair enough, since the tank started if not really had any issues with algae etc

The most gorgeous display tanks you've ever seen at one point or another likely had some sort of algae outbreak

 

[Jasongtr]

The most gorgeous display tanks you've ever seen at one point or another likely had some sort of algae outbreak

So i gather, ive been waiting for it but so far nothing really, im sure the new tank will kick my butt