macroalgae outbreak on 25 yr old live rock

[Anton Wray]

GM my fellow reef Aquarist
I have a 265 gallon reef tank with about 250 pounds of with live Fiji rock that is 25 yrs old. I noticed that after 20 yrs I had a massive outbreak of GHA and cyanobacteria.
It took several months of meticulous care flushing the rocks, manually removing GHA, CUC ,a host of chemicals, including Lanthanum and GFO to get rid of it.
This outbreak was due to persistently elevated phosphate. 0.1-1.2
All was well for the next 5 years then another massive GHA outbreak a few months ago suffocated many of my prized colonies.
I have tried flux RX, Hydrogen peroxide, CUC, 4 sea urchins ,and tangs . The system is much improved . I am maintaining PO4 at around .04, but islands of GHA keeps returning in certain areas.
I have read varying opinions on old tank syndrome, and would like some thoughts on recycling my old live rocks and creating a minimal aquascape system.
What are your opinions on sterilizing the reef rock with bleach and then utilizing an acid bath with muriatic acid or vinegar to completely restart the system from scratch. This supposedly will kill off all organics and remove the surface layer from the rock that stores phosphate .
Of course I would do this in portions . Is this even feasible?
I would appreciate any comments . It is disheartening to watch SPS frags grow into colonies and then see a massive GHA outbreak kill them.

 

[Project1004]

I’ve cooked liverocks in the past when restarting. Of course outside. Have you considered sea hare? They are probably best grazers. I don’t. Have an answer. Good luck <><

 

[EricR]

I know nothing and have no idea what "old tank syndrome" really is, assuming it's a real thing but...
I'd be tempted to work on the rocks in a separate bin of saltwater and just scrub the heck out of 'em with stiff brushes and blast them out with a pump before I went completely nuclear on them.

*I don't have the experience that you do so obviously you understand better if it's really time to do a hard reset on the rocks,,, but I don't like it

 

[Subsea]

“I have read varying opinions on old tank syndrome, and would like some thoughts on recycling my old live rocks and creating a minimal aquascape system.“


When a monoculture dominates a marine ecosystem, I see the analogy of a climax forest in land ecology. I don’t see the need for such drastic action as acidizing and boiling rock when something as simple as bringing in biodiversity with diver collected live rock can alleviate the problem.
In 55 years of reefing, I have not found reduced nutrients as effective against GHA. CONSUMERS such as urchins are a better solution.

 

[Anton Wray]

“I have read varying opinions on old tank syndrome, and would like some thoughts on recycling my old live rocks and creating a minimal aquascape system.“


When a monoculture dominates a marine ecosystem, I see the analogy of a climax forest in land ecology. I don’t see the need for such drastic action as acidizing and boiling rock when something as simple as bringing in biodiversity with diver collected live rock can alleviate the problem.
In 55 years of reefing, I have not found reduced nutrients as effective against GHA. CONSUMERS such as urchins are a better solution.

 

[Anton Wray]

Will continue to work with CUC,sea urchins, and hopefully a sea hare.
Inregards to increasing bio diversity.
Do you mean various bacterial strains or more live rock.
I have a bare bottom system

 

[fish_collector]

Cleaning rocks down to bare substrate may allow more GHA to grow. If possible, scrub rocks clean with a stiff toothbrush in a separate container and rinse well. There are not many animals that I have found that will eat GHA after it becomes filimentous. Zebra turbos would be my creature of choice once you have the GHA largely scrubbed off. I concur that nutrient management does little to make GHA go away and has to be physically removed or consumed by something.

Got some pics?

 

[Subsea]

Will continue to work with CUC,sea urchins, and hopefully a sea hare.
Inregards to increasing bio diversity.
Do you mean various bacterial strains or more live rock.
I have a bare bottom system

Diver collected live rock brings in micro fauna & fana that represent consumers & competitors:

https://gulfliverock.com/hitchhiker-id

 

[Anton Wray]

Cleaning rocks down to bare substrate may allow more GHA to grow. If possible, scrub rocks clean with a stiff toothbrush in a separate container and rinse well. There are not many animals that I have found that will eat GHA after it becomes filimentous. Zebra turbos would be my creature of choice once you have the GHA largely scrubbed off. I concur that nutrient management does little to make GHA go away and has to be physically removed or consumed by something.

Got some pics?

 

[Anton Wray]

Tow pics from back of tank where most of the GHA exist currently. Unable to remove rocks to scrub because they are cemented

 

[fish_collector]

That’s the downside of cementing them together. I left mine to just stack them for that reason.