Long Established Reef Rock Turning Black

[SnakeCharmer]

I have a reef that has been running since the late 80s. I have updated the equipment as needed over the years but it is a simple reef featuring LPS, soft corals, and polyp colonies. It is a 100 gallon tank with about 1/3 of the volume taken by live rock. I keep a light fish load (5 small fish) and a several scavengers in it.

Using Salifert test kits: (average results)
ph-8.3
kh-8dkh
ca-400ppm
mg-1400ppm
nh4-0.0ppm
no3- <1ppm
po4-<.03ppm

Over the past several months, the live rock, which has always been covered in purple/pink coralline algae, has been turning black in ever growing patches, as though the coralline algae is dying. It's not a growth on the surface like Chicken Liver Sponge, this is from the inside the rock.

It has been doing very well for so many years and I have not changed my way of maintaining it. Same as always.

Please advise. Thanks!

 

[ca1ore]

That is curious. If you take the rock out and take a sniff of the black areas, does it smell like anaerobic/sulfur? That's about the only thing that occurs to me.

 

[SnakeCharmer]

That is curious. If you take the rock out and take a sniff of the black areas, does it smell like anaerobic/sulfur? That's about the only thing that occurs to me.

I have not but I bet it would indeed smell like sulfur.

I am hoping that someone can make a suggestion as to what I can do about it.

Thanks for your reply!

 

[Maacc]

I would try getting a strong powerhead to blow out the rocks and reestablish water flow.

 

[SnakeCharmer]

I would try getting a strong powerhead to blow out the rocks and reestablish water flow.

That's a good idea. I plan to service the reef tomorrow and I will do that then. Blowing off the rock is something I haven't done in quite a while.

Thanks!

 

[ca1ore]

I'd be careful. If your rock has really gone anaerobic, spreading it around the tank strikes me as unwise. It may be time to get new rock if so.

 

[Retro Reefer]

Most likely old tank syndrome.. dying bacteria inside the core of rock from lack of flow because of clogged pores and the encrusting coralline.. I wouldn’t try cleaning it inside Tank maybe do a piece or two at a time in a bucket.. probably best to start pulling it out a little at a time and replacing it with new rock.

BTW ... Welcome to R2R!!

 

[ZoWhat]

+1

LR does have a life span. I would say 30+ yr old LR is so saturated being enclosed in a glass box...it needs to be thrownout & replaced

When I worked for a coral shop and asked to teardown a large tank with 8+ yr old substrate. The substrate was like concrete bc it was so saturated with crapola.......substrate broke off like bricks


.


.

 

[SnakeCharmer]

When I worked for a coral shop and asked to teardown a large tank with 8+ yr old substrate. The substrate was like concrete bc it was so saturated with crapola.......substrate broke off like bricks

I've seen that happen before in another tank.

THANKS FOR YOUR HELP EVERYONE. I had a feeling that this is what you all would say. Time to rebuild, slowly.

 

[brandon429]

Before you toss out very rare rock, cross section some suspect pieces. Hammer, easy break wrapped in a towel can you post good pics and smell testing of insides

 

[SnakeCharmer]

Before you toss out very rare rock, cross section some suspect pieces. Hammer, easy break wrapped in a towel can you post good pics and smell testing of insides

Yes, I will do this to one of the blackened rocks today while I am in there working on the reef.

 

[SnakeCharmer]

The pics are a little blurry but it's the best my cell phone could do.

The rock does not have a sulfur smell on the outside or the inside. In fact, it has no scent whatsoever on the outside in the black areas or in the coralline areas. That seemed odd to me. Usually a pungent, biological activity odor is detectable. The inside of the rock smells like stale fish.

From the pics, you can see that the darkened area does go down into the rock below the surface. The darkened patches have spread around even more this week. In fact, there is more algae growth and diatoms than usual. Even a few patches of hair algae starting.

I bumped up the magnesium level to combat the hair algae and I did a large water change. I used a small pump to systematically blow out ever inch of rock surface that the jet could reach. I was able to remove most of the detritus that settled. In the past, there was a surge of improvement in the reef a few days after doing this (larger, more extended corals).

We shall see what happens.

Advice and opinions are welcomed!

 

[brandon429]

This is now linked to the microbiology of cycling thread.

The entire thread is about the science of testing the least, in order to cycle every type of aquarium, and we just like old live rock.

it has permanent self-feeding abilities, if you kept it only hydrated but never fed, and was oxygenated, the live rock bacteria would never cease to function.

you cannot starve bacteria off this type of rock, that makes it amazing in a microscopic way, even if a sponge is annoying and being selected for after all these years


Im not sure if you should keep or rehab it, dang 30 yrs don't give up

your're dealing with fascinating boring (acid etching, literally bores into rock) dark sponges I bet, and agreed, they're hitchhiker wraiths but amazing biology. Though there's a complete risk of cross vectoring by using anything from this tank in a new tank, or placing new live rock in here, I just hate to see the rock go. Though this is a long boring read, your rock is the oldest in-tank example we have of group B rock.

https://www.reef2reef.com/threads/long-established-reef-rock-turning-black.443685/#post-5051586

your coralline is literally accreted into whorled reef formations its so old. You win best coralline cultivation/over time contest in reefing. and macro documentations.

 

[brandon429]

@Nano sapiens
hey you gotta admit its rare to see absolute proof up close of something so old. visual benthic indicators/off the charts. cross sectioning/layering, info gold regarding tank aging OTS etc, this is puzzle piece rare. the sponge is a hassle but Id get serious about spot peroxide work, and rasping, and see if it can be burned out. at least try to knife tip rasp that stuff off a rock as fully as you can, then peroxide the clean areas avoiding the pristine coralline, let bake a sec, rinse put back and try and guide out

his OTS manifestation is a rascal hitchhiker. no different than someones bryopsis after 27 years...this one manifests as a wraith but its not a bacterial imbalance I bet as Ive never seen marine versions of that pigmented anything but whites/cream/browns and purples but all black I vote sponge unidentified what do you think.

if he just ridded the invader that rock sails for another millennia. I feel like we're shooting the mare here before we even attempt to build her a robot leg. theres always something to hand guide in reefing, since we present .000000103% of the total macro and micro competitive grazer complement in our homogenized reef tanks.

 

[radiata]

Did you happen to try removing the black stuff with a stiff brush?

 

[Dom]

It looks like mold to me. But can mold grow under water?

A quick google search generates plenty of hits and apparently mold can grow under water if it is nutrient rich.

What do ya think?

 

[ZoWhat]

Once you go black....you never go back

 

[radiata]

It looks like mold to me. But can mold grow under water?

A quick google search generates plenty of hits and apparently mold can grow under water if it is nutrient rich.

What do ya think?

Any chance such mold is toxic?

 

[SnakeCharmer]

Did you happen to try removing the black stuff with a stiff brush?

No, but I did run my finger tip over it to see if it could be wiped off. What I can say is that it does not appear to be growing on top of the rock, it seems to be a pigment change in the rock itself. It feels no different than the coralline algae growing next to it. I placed the small broken piece, from my pics above, back into the reef. I will try to brush it off when I have a chance. Thanks for the suggestion.

 

[Dom]

Any chance such mold is toxic?

It grows in the air. It grows in nutrient-rich water.
It's toxic in the air. I would think it is toxic in the water.

But I'm guessing.