What are these black spots sticking on the rock?

**14litre** · 21st Apr 2015, 17:15

Does anyone know what are these black spots sticking on the rock?

I cleaned it once and it formed back again.

**Urban Aquaria** · 21st Apr 2015, 19:14

From the video, the color of those spots look quite similar to your soil color... maybe they are just broken-down soil particles that got circulated around the tank and settled on the rock surface?

**14litre** · 21st Apr 2015, 21:24

Originally Posted by Urban Aquaria

From the video, the color of those spots look quite similar to your soil color... maybe they are just broken-down soil particles that got circulated around the tank and settled on the rock surface?

I have the same thought too.
So I went to scrub it off. To my surprise, it formed back again.

I did not see any particles floating around, neither do I see the substrate moved by the water current, so kinda puzzled if it's the soil. So I thought it could be algae or something else.

it's good to hear that it's not algae on the first look, I'll leave it and keep monitor.

Thank you once again for the insight.

**wooty100** · 23rd Apr 2015, 10:52

My guess should be particles of soil. You have livestocks and current in the water that is pushing the particles around? I have a similar rock and it sometimes have debris on the surface due to fishes and hangon waterfall current

**skytan** · 25th Apr 2015, 01:55

Do you have any of those wood that have plants tied on them from LFS and shrimps together?

my shrimps like to chew on those and the gravel will have lots of there when I do WC

**Dylan Chin** · 25th Apr 2015, 09:52

I would think that it is the soil particles. However, algae can form on the small cracks in the rocks too. If its algae then just throw some shrimps in there? Haha, well I guess if you want to confirm you can stick your hand in there and feel if the rock is slippery. Slippery = algae I guess

**14litre** · 25th Apr 2015, 18:03

Originally Posted by wooty100

My guess should be particles of soil. You have livestocks and current in the water that is pushing the particles around? I have a similar rock and it sometimes have debris on the surface due to fishes and hangon waterfall current

Thanks for sharing.

No livestocks yet. Still cycling the tank and i do have strong current. I'm changing my filter soon and will monitor further. It's kinda unsightly with the black particles on the stone.

**14litre** · 25th Apr 2015, 18:04

Originally Posted by skytan

Do you have any of those wood that have plants tied on them from LFS and shrimps together?

my shrimps like to chew on those and the gravel will have lots of there when I do WC

Thanks for sharing.
Not at this moment. My tank has stones, substrate and plants only. Thats a good point too.

**14litre** · 25th Apr 2015, 18:07

Originally Posted by Dylan Chin

I would think that it is the soil particles. However, algae can form on the small cracks in the rocks too. If its algae then just throw some shrimps in there? Haha, well I guess if you want to confirm you can stick your hand in there and feel if the rock is slippery. Slippery = algae I guess

Thanks for sharing.
Haha, ya, that should be a quick and easy test. I'll check it out. Cheers.