Live Rock

[SCOOB]

this is kind of in response to Martin's excellent response in the 'old tank syndrome' thread.

Live rock, we all agree, is essential in the running of a successful mature reef system. it is taken from the reefs in most cases and contains lots of goodies that have built up over several years. as far as i know even cultured live rock from farms such as 'tampa bay salt water' are left un touched for 4-5 years on the sea bed. Martin mentioned storms in his response as a means of clearing a section of sea bed, this imo would also destroy, create new rock zones and ofcourse new environments for the 'newly moved' rock to experience.

is it possible that over time our live rock gets clogged, not necessarily with detritus, but over time certain bacterias or at least the way in which they work get deteriorated or exhausted within a closed system?

would replacing large quantities as part of Martin's 'large maintenence regime' perhaps delay deterioration and give the tank a new lease of life, perhaps every 3-4 years?

and if so, would it be best to swop with 'fresh' rock from your lfs or to swop with other reefers maintaining the same regime?

if you were to swop aged live rock from a closed system with another reefers aged rock would this be beneficial (like the storm mentioned) or is it likely to be something synonymous with all closed systems that renders it a pointless task?

[jacksok]

Good question Scoob.

If liverock does age might it instead be due to calcerous algae build up impeding the flow of water through the rock, rather than detritus? In which case systems unlit cryptic zones of liverock might offer greater longterm stability? Is there any evidence of this?

Keith

[SCOOB]

keith,
using the 'storm' theory as well as general predation would explain how mother nature inhibits calcerous algae from sealing up all the reefs. i plan to have about 40kg of live rock in an unlit part of the sump, hoping to rotate my rock every couple of years but still maintaining each pieces practicality by keeping it within the closed system. I am sure you are correct that calcerous algae would deminish the rocks abilities but there must be more to it in the longer term. surely the way to stop 'old tank syndrome' (with regards to live rock) can't just be to make sure you always have a hungry long spined urchin.

[simon garratt]

This falls very much in line with Martins response to the Old tank syndrome.


Ive thought on this subject for quite some time now, and come to a few possible conclusions based partly on the ramblings of Mr Shemick and mixing in a bit of chemistry theory as well.


Over the course of the life of any LR we put into the system, the natural process of calcareous buildup and precipitation lead to a gradual reduction in the porosity of the rock at a surface level (maybe not so much on the shaded underside, but definitely on its upper surfaces) and the binding of certain quantities of impurities that come in through various sources IE metals in salts etc, unknowns in the RO as a low TDS reading etc etc, even food containing chemicals etc.. Its fair to say that in only a few years worth of growth its very likely if not unavoidable that your LR will take up an awful lot of contaminants and lock them away mixed into the layers of calcium carbonate precipitation/calcareous algae growth..

As this happens the rock slowly starts to loose its porosity in certain regions resulting in a reduction of flow and ever decreasing pH values internally as what were previously well serviced 02 areas are strangled to the point that they then become de-nitrification zones. Take this one step further and pH values may drop down to a degree that de-calcification/dissolution starts to happen and previously locked up impurities are released back into the system casing problems. If you take into account Martins comments regarding the first two-three year good period and then the gradual increasing difficulty in which the system maintains good conditions then i personally think that this is a viable scenario that could be considered.


whats the answer? well I'm a big fan of diversity which stretches to LR critters, and especially those that bore and burrow. Its fair to say that to some degree the growth and protection of these organisms is one area that should be more heavily studied in cases where tanks have remained stable for longer periods. I have a hunch that its this persistent tunnelling and boring activity that may hold off those pitfalls listed above.

I have noticed that certain tanks that contain fish such as copperbands, butterflies etc frequently suffer a complete lack of these types of organisms including boring fan worms etc So i have my hunches that live stock choice is just as important to the long term sustainability of a system at ground level, as it is to the daily challenges of mixing several species in closed space in the interests of having a nice colourful display (sometimes we are our own worst enemies)


The only other viable solution i see would be to change a % of the rock work (that which has been most heavily colonised) every few years for a fresh batch along the lines of what is now frequently recommended for sand beds. This isn't to say what has been removed is useless, it simply needs servicing to bring back its porosity to prevent future dissolution (maybe dry tumbling in a cement mixer for ten min to scour off the surface layer of calcareous algae buildup) and then let it flush itself out in the confines of a separate re-maturing vat for a few months.


just a few thoughts.


regards

Si. :)

PS. Ill probably join both this topic and the OTS thread together seeing as they are so closely linked.

[SCOOB]

yeah sorry they are seperate threads, at the time it wouldn't let me post this question in the OTS thread.

thankyou for the very informed responses. this is what makes you guys the experts in my opinion, what a fantastic new forum :thumbsup:

ph levels plummeting within the live rock causing the binding calcium do go into dissolution is not an angle i'd ever though of before. would it be worth taking the old rock and 'tumbling it in the cement mixer' with an acidic solution to force start this process before re-curing for a few months.

maybe in a few years when there are more and more long standing tanks this could be a good money spinner, send me your duff rock and £20 and i'll re-energise it for you :whistling: hmmmm.

would you say, given records and own personal experience that live rock is a safer, if more expensive way to create equilibrium in a tank over a DSB. i know each has it's merits but from the science that i understand, a DSB (all be it poorly managed) has a higher chance of releasing nasties than aforementioned rock.

[simon garratt]

would you say, given records and own personal experience that live rock is a safer, if more expensive way to create equilibrium in a tank over a DSB. i know each has it's merits but from the science that i understand, a DSB (all be it poorly managed) has a higher chance of releasing nasties than aforementioned rock.

Yes deffinately. Although LR and DSB's share the same chemical and biological traites they are very different animals in composition and rate of fuction. A DSB's ability to 'rapidly' release bound compounds, makes it a more risky and problematic beast if not managed properly especially where system pH management is concerned). whereas LR could be considerd as your backdoor agressor which slowly creeps up on you unawares. I think this may have something to do with why people claim they cant find the cause of problems with long term systems. It may be just that they are looking in the wrong place. (sand bed gets the blame again, even though its had 25% change every year).

Sometimes the fault can be right in front of our faces to degree we cant see it screaming at us......... :)

Obviously, this is based largely on theory, but its a valuable consideration IMo and one that shouldnt be dismissed 'too' off handedly. especially in the event of system decline without visable cause.

regards

Si.

[~Tony~]

Is there any advantage in 'cooking' the live rock to rejuvenate it after it has been in the tank for a long time?

I believe the theory is that keeping the rock in a dark, zero nutrient environment - with regular complete water changes - for several weeks will force the bacteria to consume all the trapped detritus and phosphates, ready to begin a life anew back in your tank.

Would this help?

Tony

[tuan]

I rejuvenate my live rocks by swapping pieces into and out of the refugium. This covers Simon's point on maintaining the diversity of boring worms and critters on the rocks as the refugium have zero predation.

Not too convinced that calcerous coralline algae actually covers that much of the rock to render it impervious. On close examination of live rock pieces that I remove the surface isn't actually solid with coralline algae as the algae tends to grow where if there is light, but the rock is full of little pits and pockets and so the surface isn't one solid mass. Of course the underside is of the rocks are also not covered as well.

The theory of trapped phosphates is also unconvincing IMHO. If the tank has always been kept in low organics/phosphate level then why would so much be absorbed?

[popsock]

I've noticed that in my heavily stocked (fish-wise) tank that phosphate/silicates cause nuisance algae on the glass before the rowa reactor can remove it. Ultimately I guess nuisance algae in the tank must be much more effective at using PO4 rather than the phosphate needing to pass through a filter. The PO4 level tested wtih a Merck kit if 0 and always has been since day 1 (system is now 4 months old).

Anyway... I would guess that its plausible that phosphate could be absorbed by rock before its removed by the filter, in a manner similar to the algae?!? That could explain why PO4 is found in rock that's been kept in a 0ppm environment.

Maybe.

:thumbsup:

[Acropora]

Hi

I should have mentioned earlier, that last time I undertook the aforementioned maintenace, I replaced about 20% of the live rock, in my mind to re-plenish some of the lost bio diversity ('critters' and biological capacity). The old rock went to a friends tank, as base rock.

Regards


Martin Lakin