View Full Version : Grotto Rock
I have a nunber of large boxes of this stuff by UnderWorld (from years ago and never used). My question is, can I use this in a reef system. I am confused as Andy from AquaWorld said, don't touch it with a ten foot barge pole as it has heavy metals in it and Justin from Cheshire Waterlife just said he wouldn't use it because it is sharp and harbours muck?
Any clarity would be appreciated
John
I wouldnt touch it personally.
I really don't see the point of adding dead rocks to the tank, with the exception of dead live rocks which may be repopulated later, rocks that have little filtration nor supports much live should be minimized.
Circulation is so important in the tank as well as having space so why fill it with dead rocks. One tiny piece of porous live rock is worth many times the equivalent of dead rocks, especially grotto rocks. Filling the tank with dead rocks just make things worse.
Living rocks in the tank is so crucial to a sucessful reef. Spending more on good quality pieces is well worth the investment.
Originally posted by tuan@Dec 18 2005, 08:25
I wouldnt touch it personally.
I really don't see the point of adding dead rocks to the tank, with the exception of dead live rocks which may be repopulated later, rocks that have little filtration nor supports much live should be minimized.
Circulation is so important in the tank as well as having space so why fill it with dead rocks. One tiny piece of porous live rock is worth many times the equivalent of dead rocks, especially grotto rocks. Filling the tank with dead rocks just make things worse.
Living rocks in the tank is so crucial to a sucessful reef. Spending more on good quality pieces is well worth the investment.
Thanks for the reply, I have decided to bin it
John
I have found no problem using this in numerous systems including the large reef systems that I set up at the London Aquarium.
It is porous so an excellent filter medium but obviously does not carry the livestock that live rock will.
simon garratt
24-12-05, 11:15
Clayton. Just out of curiosity. the LA systems,......... did they have commercial sand filters attatched ie linked to a central water treatment area, or was each system run seperately with no additional filtration exept what was in the tank?
Regards
Si.
As Reefworks says it is very porous and because of this it is indeed an excellent biological filter medium, which is why it is broken up in to bits and sold as Alfa-grog (a biological filter medium) but, as most of us have probably learnt, biological filtration can be a bad thing in a reef... ;)
simon garratt
24-12-05, 15:17
but, as most of us have probably learnt, biological filtration can be a bad thing in a reef...
Sorry mark but im not sure i understand that comment. :huh:
fwiw.... sand, Lr, glass, pipework, in fact 'every' surface within the confines of a tank that comes into contact with your water is a biological filter. Your system and the organisms present couldnt survive without it. The only variance between the capacity of all these medias for bilogical activity is the porosity (or lack of in the case of a glass pane) and the resultant levels of available 02 which determin the range of nitrification/de-nitrification coverd.
The real problems arise when a media is used in such a fashion that its abilities or scope is deliberately/accidentally held back. ie the use of highly porous (full range)media in trickle towers which can lead to an imbalance between the nitrication properties of a system and the de-nitrification ability especially where over feeding or where there are sutable alternatives at hand to correct the imbalance..
regards
Si. :)
I just meant that most reefers I know have found that things like Bio-Balls and most other Bio-media end up causing a Nitrate problem because they are a Biological filter medium which provides a massive surface for biological filter bacteria to colonise thus they produce a lot of Nitrates.
I know the biological process takes place naturally on any surface and that the bacteria are there anyway, but within these media they are able to reproduce in to massive colonies.
To me, having a tank full of Grotto rock would be as much a Nitrate factory as any cannister filter filled with ceramic media.
I did use Grotto rock myself before switching to Live Rock and at the time I thought it was great, until I had a massive outbreak of brown sludge and cyano all over the tank. :wacko: Water parameters seemed fine, in fact Nitrates were never higher than 5ppm and were normally 2ppm.
We tried for about four months, with all sorts of things and in all sorts of ways to rid ourselves of the sludge. :blink: then in the end we changed the Grotto rock for Live Rock and the brown sludge/cyano has never returned, in fact the only algae we ever get now is coraline and the odd bit of green on the glass.
Even though our Nitrates were showing to be low on the tests we now think that the rampant growth of the brown sludge/cyano was utilising the excess Nitrates, hence we didn't see them on the tests and the only thing we can put it down to was the Grotto rock.
Pic's below of the algae that used to grow, we did try cleaning it out (many times!) but it was back just as bad within a day! yet as soon as we got rid of the Grotto rock it vanished and has never returned.
http://aquatic.uk-life.org.uk/uploads/post-135-1120571888.jpg
http://aquatic.uk-life.org.uk/uploads/post-135-1120571935.jpg
simon garratt
24-12-05, 19:38
Ah, now i see where your comming from. ok lets split this down to two clearer issues.
1. Restrictive bio filtration through placement and application.
This is what people actually mean when they come up with the phrase 'nitrate factory'. ie trickle filters and powerfilters. The use of media in these high 02 areas prohibits in the case of bioballs / or severly limits in the case of alfagrog the ability of the media to hold balanced colonies of both nitrifying and de-nitrifying bacteria, consequently if the system isnt able to make up this difference in other areas (ie a sand bed) then there is the very likely possibility that an imbalance will occure wherby the production of N03 is at a rate faster than the systems ability to de-nitrify back to free nitrogen. result is escalating no3 levels , and the need for more waterchanges to combat it.
2. Incomplete bio diversity within a media.
This is where a bare media is used as a replacement for fully functioning and diverse LR and isnt of such a standard/material that it will encorage the migration of organisms from nearby real live rock. In such cases its quite possible that the rock will become festooned with particulate matter over a short period of time with a minimal cleansing action taking place that would normally occure with heavily predated/scavenged, and grazed real live rock. (especially the cleansing, burrowing and boring activities of worms etc.)........needless to say, some materials are just not cut out as an alternate media to LR which is inherantly soft and easy to bore/tunnel through for a vast majority of organisms.
Probably the biggest factor commonly forgotten when using a bulk of dried or biologically innert rock with just a small seeding of real LR, is how long it will take for that rock to colonise to the degree it can be considerd really live. (note that 'Live' doesnt just mean bacterially). Im hazarding a guess that 90% of people starting up systems with a bulk of reefbones or grotto whichever, are totally unaware that LR culturing facilities frequently leave freshly deposited land based aragonite rock in the culturing areas for three to five years before it is considerd to be of equally good quality as normally mined oceanic rock and therfor ready for sale. consequently the systems are stocked way too quick for the system to cope with the waste products produced and suffer from clogging of the rock structure, poor porosity and reduced bacterial action and consequently an overal downturn in the systems ability to hold good water conditions with evidential algae problems etc..
IMO, the use of alternate/cheaper rock as a base is fine as long as you understand what it needs to go through to be at a stage you could really consider it 'alive', and even then its net worth as a substitue will only be comparable to natures real stuff if it displays the same porosity characteristics and softness to allow organisms to work/live upon 'and' in it successfully. This is why most of the pro's still advocate the use of good quality (real) live rock as the bulk of the rock structure with only a smaller % as fake/dead base rock.... if at all.
regards
Si.
Yep, agree with that... :thumbsup:
Our reef is 100% Live rock now and I wouldn't recommend trying to cut corners by using Grotto rock as it just doesn't work... :wacko: ...as we found out to our cost!
May be it would be okay in small amounts but for just a small saving why risk it?.. ;)
With regards to the London Aquarium 'reef' systems (if you could call them that several years ago!), the tanks were connected to a central sand bed system (but not those of the shark displays etc).
This along with a whole multitude of other problems caused continual deaths of just about every coral they put in them.
When I started work there I stripped out the system and seperated each tank (threee 3,000 - 4,500 litre systems) and set them up as Berlin or Berlin adapted systems. Alfa coral was used in two of the systems behind live rock to builod up the aquascaping. There were no problems with the tanks in terms of nitrates or metals. All sps systems grew excellently. I left there a year ago though and have no idea what state the systems are in now.
"To me, having a tank full of Grotto rock would be as much a Nitrate factory as any cannister filter filled with ceramic media."
This is simply incorrect Mark, due to the porous nature of the media Nitrate can be converted into free nitrogen in the same way that it is in live rock.
"Our reef is 100% Live rock now and I wouldn't recommend trying to cut corners by using Grotto rock as it just doesn't work... ...as we found out to our cost!"
I would imagine that the previous problems in your tank were due to other reasons.
Combinations of live rock and grotto rock work very well in reef systems, provided that you establish the correct balance in the nitrogen cycle for you biological load you can use whatever biological filter media and methods that you like.
hth ;)
Great thread, dispelling some myths through experience.
Kev
This is simply incorrect Mark, due to the porous nature of the media Nitrate can be converted into free nitrogen in the same way that it is in live rock.
I'll take your word for it, and I thought the same when we got it, but if it wasn't high nitrates that were causing the problem then it was something else contributed by the Grotto rock, IMO.
I would imagine that the previous problems in your tank were due to other reasons.
Possibly, but doubtful as we spent around six months trying to rid ourselves of the 'sludge' and during that time these are some of the things we tried:
Increasing lighting (wattage)
Increasing lighting (duration)
Decreasing lighting (wattage)
Decreasing lighting (duration)
Different spectrum of lighting
No lighting!
Larger water changes
More water changes
Less water changes
No additives (Kalk, Iodine, Magnesium, etc.)
More additives than originally used
Different additives than originally used
Lower temp
Higher temp
Lower salinity
Higher salinity
Lower pH
Higher pH
More flow
Less flow
Increased Carbon filtration
Increased Mechanical filtration
Daily removal of all 'sludge' for one week
Leaving 'sludge' untouched for weeks to see if it would burn out
:wacko: ...that's all I can think of at the minute!.. :lol:
None of what we tried made any difference and it was still just as bad after the six months!.. :blink: ...so we gave up trying to get rid of it and just left it to it... :( ...then a couple of months later we had the money to buy Live rock, which we did... :D ...ever since there has not been a single sign of the 'sludge' or anything else like it... :) ...so, IMO, it was something to do with the Grotto rock.
Combinations of live rock and grotto rock work very well in reef systems, provided that you establish the correct balance in the nitrogen cycle for you biological load you can use whatever biological filter media and methods that you like.
I agree there, Grotto rock is probably fine so long as you have enough denitrification going on in your system to cover any excess Nitrates, personally I'd rather not take the chance of getting the balance wrong and therefore prefer to play it safe with all Live rock... ;)
simon garratt
29-12-05, 17:10
I think the first thing to realise is that Cyano bacteria has the ability to utilise various scources of energy, from decomposing matter to bare bones free nitrogen gas combined with a minimal amount of organics. Hence its common occurance on sand beds during transitional bacterial blooms (first 6 months or so when nitrogen bubbles are forming en-mass, or if there has been a sudden change in feeding proportions/load). If anything its rare for nitrate on its own to be a cause of Cyano. its allways coupled with something else be it lack of flow through the rock, lack of cleansing by scavengers grazers, or other attributable causes.
Lighting is commonly played with when Cyano strikes and i cant see why. its never scientifically been attributed as a cause or cure. By far a better method is DkH control which if elevated to 11. or above will usually see the end of such problems and cure pH suppression problems at the same time.
Ultimately its all about organics. The substrate (as long as it doesnt harbour any foreighn materials) is a side issue that has iether a hindering property or benifit depending on how its handled. but ultimately organics are the cause and how you handle them.
Hence most successful reefers penchant for well oversized skimmers.
when i get 5 min Mark. Ill run through the pros and cons of each of your trials to explain in more detail why they do and dont work under cirtain circumstances.
Regards
Si. :)
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