HELP Black pieces apprearing in Crushed coral substrate HELP

[aquablizz]

Looking for any information or advise.. All of a sudden I have noticed that I'm getting a lot of my pieces of crushed coral turning black in my fish only tank... Has anyone ever come across anything like this. I am posting a picture

My fish all appear to be fine. The main display tank is 75gal and my sump is 30 gal.
Average fish load. I am a light feeder.
zero nitrites and near zero phosphates.

Always have battled nitrates in the 80-100 area
Tank setup is approx. 15 years old.

I believe it is getting worse.

Any ideas out there??

 

[jenkinscrew2578]

Do you run carbon on your system?

 

[saltyfilmfolks]

If you take it out of the tank, does it smell?
How does it feel? slimey? Does it blow off the rock?

 

[WetWhistle]

Any egg smell? Usually when stuff like this turns black it is sulfurs. I have not seen it in upper layers of substrate in a healthy bed but I have in lower areas of substrate with no flow or a canister filter that was unhooked and the media was left in and died off. Turning black. Is substrate getting kicked up from under a rock? That had lack of flow... Or it could be carbon. Old substrate can do this as well if it has been used a long time but this is rare.

 

[aquablizz]

I do run carbon but it does not smell.. Also it does not appear to be slimey..

 

[aquablizz]

under better lighting it seems to have taken on a very very dark purple color like cyno.. it is next to impossible to scrap it off the pieces using my fingernail so it's very tough..

 

[saltyfilmfolks]

under better lighting it seems to have taken on a very very dark purple color like cyno.. it is next to impossible to scrap it off the pieces using my fingernail so it's very tough..

with all the life in the tank plus food, Im kinda guessing sponge.
Im guessing its like rubber.

 

[aquablizz]

Not soft at all... It's all I can do to scrap it off the piece.. and when I get a chip off, it does have a reddish black appearance..

very strange that they are individual pieces which has me puzzled.. I raked down to the glass bottom and there is nothing out of the ordinary.

 

[saltyfilmfolks]

Not soft at all... It's all I can do to scrap it for the piece.. and when I get a chip off, it does have a reddish black appearance..

so its hard? like coralline? whoa.

Send and third opinions #reefsquad

 

[aquablizz]

I have some coralline on the glass and rock but mostly the typical pink .. this stuff is very very dark purple and near black in color.. I hesitated to use the word coralline but it came to mine when I was trying to scrape it..

 

[Rick.45cal]

It's likely a photosynthetic black sponge. I have them ALL over my tank (but only in areas that get light). They won't hurt anything (that I am aware of). I happen to think mine are very cool, there aren't too many things that are appear to be absolutely black like these do.

 

[saltyfilmfolks]

I have some coralline on the glass and rock but mostly the typical pink .. this stuff is very very dark purple and near black in color.. I hesitated to use the word coralline but it came to mine when I was trying to scrape it..

no sweat. I only have a few in one tank.. Ill put a thumb nail to it again. Its def tough and near impossible to get off.

 

[aquablizz]

It's likely a photosynthetic black sponge. I have them ALL over my tank (but only in areas that get light). They won't hurt anything (that I am aware of). I happen to think mine are very cool, there aren't too many things that are appear to be absolutely black like these do.

I always thought sponges were soft... this stuff is like a crust...

 

[saltyfilmfolks]

I always thought sponges were soft... this stuff is like a crust...

got a close up?

 

[Rick.45cal]

Here is a picture of the black photosynthetic sponges that are all over my tank.

It's taken with an orange filter and an iPhone so the color is a little off.

 

[WetWhistle]

Coralline growth is possible or some form of sponge or bacteria is also possible.

 

[Rick.45cal]

I always thought sponges were soft... this stuff is like a crust...

I've never tried scraping mine off, or even really touching them. They don't appear to be very soft. You have to remember that some sponges excrete a silica based skeleton (basically glass). Careful touching them! There's lots of different types of sponges, my black ones seem to mostly stay very small,, low, encrusting, blobs (for lack of a better word).

 

[aquablizz]

here is a close up shot that I just took. showing the contrast of what they used to look like..
I have never had these turn up in 15 years so that is why I became quite concerned because they seem to be getting worse..

Remember these are just tiny substrate pieces approx. 1/4"

 

[Sabellafella]

here is a close up shot that I just took. showing the contrast of what they used to look like..
I have never had these turn up in 15 years so that is why I became quite concerned because they seem to be getting worse..

Remember these are just tiny substrate pieces approx. 1/4"

15 years and wow thats odd. Try to hammer one down to see if the inside is white. It could indeed be an encrusting form of life

 

[Rick.45cal]

Yeah that looks totally different