Artificial oyster rocks can replace reef rocks used for biological filtration in marine aquariums

[dw1305]

Hi all,
This came out of the discussion on <"is expensive bio media worth it?"> in freshwater tanks, but it looks quite interesting.

I know nothing about marine tanks, so any comments would be much appreciated.

Cohen, F., Cabral, A., Lillebø A & Calado, R. (2021)
<"Relieving pressure from coral reefs: Artificial oyster rocks can replace reef rocks used for biological filtration in marine aquariums">
Journal of Cleaner Production, 325, <"Redirecting">.

Natural reef rocks have been harvested from the wild for decades to supply the marine aquarium trade. These rocks have been used in home aquariums mostly as substrate to safeguard biological filtration, especially for nitrification. Producing artificial rocks can be a sustainable alternative to the harvest of natural reef rocks from the wild, thus promoting coral reefs conservation. Nonetheless, there is a lack of scientific knowledge on standard formula to prepare artificial rocks, as well as on their potential to promote nitrification. The use of oyster shells, a by-product from oysters’ aquaculture, appears as a promising ecological and economic approach to produce artificial live rocks. Thus, we aimed to develop a standard formula to produce artificial rocks made with oyster shells and test its potential use as a substrate for biological filtration in marine aquariums. For that, we prepared artificial oyster rocks with different sized fragments of oyster shells and compared their ability to promote nitrification of ammonium nitrogen with that of natural reef rocks and fragmented oyster shells. The formula was set at 1 g of dried cement (white Portland cement with limestone) per 3.1 g of dried oyster shell fragments. The volume of water used to prepare this mix was set as 50% of the cement weigh. Our results indicate that artificial rocks made with oyster shells and cement display an ability to promote nitrification similar to that of natural reef rocks, promoting a slight decrease in pH and without releasing PO4–P. All treatments with substrate were able to oxidize up to 21 mg.L−1 of TAN (total ammonia nitrogen, initially added in the form of NH4Cl) within a 48-h interval. In other words, it is possible to safely assume that all tested substrates oxidized an average of ∼4.4 ± 0.1 μg of TAN.g−1.h−1. Thus, our results support that artificial rocks made with white Portland cement and oyster shell fragments are a sustainable option to safeguard a suitable biological filtration in marine aquariums......

cheers Darrel

 

[shangman]

This is awesome, thank you for sharing! I'll have to make some moulds for my own custom-shaped oyster shell reef rock when I try marine in the (hopefully near) future

 

[ScareCrow]

People have been doing some pretty crazy things with Portland cement, rock salt and water softening salt, to create artificial live rock. It can look pretty impressive and comes with the benefits of no nasty hitchhikers or depleting rock from the ocean. You do need to soak it for a while for the alkalinty to stabilise though.

 

[dw1305]

Hi all,

This is awesome, thank you for sharing!

I'm going to assume that you could access the full paper OK?

it can look pretty impressive

Which reminds me that I should have put the picture in:

The "Artificial Rock - Small shell Fragments" performed more successfully (out of the oyster shell rocks) at the start of the experiment, but by 20 days there was no difference in nitrification between all treatments (fragmented reef rocks (FRR), fragmented oyster shells (FOS), and artificial rocks made with small shell fragments (ARS), medium shell fragments (ARM), and large shell fragments (ARL)).

pretty crazy things with Portland cement, rock salt and water softening salt

Salt to create the holes in the "rock"?

cheers Darrel

 

[ScareCrow]

Salt to create the holes in the "rock"?

Exactly the different size salt crystals used (rock salt and water softener salt) result in smaller and larger holes in the final rock after soaking. It's a very clever solution and much better than flying boxes of damp news paper covered rocks around the world, hoping that some of the life inside will survive.

 

[shangman]

I'm going to assume that you could access the full paper OK?

Not right now, but you added the proportions of the mix in the quote in so that's perfect! I'll be doing a marine project with a friend that works for a university part time so I should be able to access it via them too. Super useful stuff.

 

[dw1305]

Hi all,

Not right now, but you added the proportions of the mix in the quote in so that's perfect!

If any-one does want the full paper? PM me your email address and I can send the pdf.

I also know that you can buy oyster shell fragments cheaply, in different grades, as <"Chick(en) Grit"> *

* if the link stops working that was £2 per kilo at P@H (also £2.50 per kilo at Wilko's)

cheers Darrel

 

[not called Bob]

I had some made up of just Portland cement and waste shells (chicken grit) chucked them in the loo tank for a good few months to stabilise. Once in the tank they were soon colonised, though for the main scape I used shop available ceramics,

 

[Denstone]

Hi all,

If any-one does want the full paper? PM me your email address and I can send the pdf.

I also know that you can buy oyster shell fragments cheaply, in different grades, as <"Chick(en) Grit"> *

* if the link stops working that was £2 per kilo at P@H (also £2.50 per kilo at Wilko's)

cheers Darrel

Hello, could you send me the entire pdf of the article? email Henry.denstone@gmail.com

 

[dw1305]

Hi all,

Hello, could you send me the entire pdf of the article? email Henry.denstone@gmail.com

Will do.

cheers Darrel

 

[tam]

Artificial rock is, I think, fairly standard now in the marine hobby. However, it makes aquascaping rock look cheap!

Here's an example of what's commonly used: Real Reef Rock | Decoration | Charterhouse Aquatics it

It's also shaped with 'scaping' in mind. A lot of the live rock 20+ years ago was more 'rock' like lumps where this is very textured - a bit like the difference between a lump of bog wood and some manzinita. It does come in different colours/styles.

 

[dw1305]

Hi all,

However, it makes aquascaping rock look cheap!

The pricing is "interesting", and so is the phrasing of the blurb.

..... Real Reef is a 100% coral reef eco-friendly product made and farmed in the U.S.A.

So it just says it has nothing to do with coral reefs, not sure about "farmed", I'm guessing it is in there for a reason, and that reason is to put you off the scent?

Farming oysters
The adaptability of oysters makes them a good species for aquaculture, and because they are filter feeders, they rely totally on natural plankton in the sea for feed. Farmed oysters start life in a hatchery, where they are spawned and hatched in a controlled environment. Once they are big enough, they are moved to nursery tanks or ponds until they are large enough to be transferred to sea. A variety of different methods are used to on grow oysters. Some oyster farmers use mesh bags laid on low trestles staked to the beach in the intertidal zone, some use bags, trays or cages suspended beneath longlines, and others place them directly on the seabed.

In fact I'm going to say the farmed bit is actually <"made from farmed Oyster shells">* edit, it isn't, it is the time the products spends <"maturing in a bioreactor">.

This green product is made from natural materials, with the same building blocks as wild coral skeleton live rock.....

Ok, that just means it is made from calcium carbonate (CaCO3), so made from a <"mollusc shell">? <"and cement">? <"and salt">?

Whether in a reef or fish only aquarium, Real Reef stays purple dead or alive. The product is pigmented with non-toxic colours to duplicate the most beautiful encrusting coralline algae mother-nature has produced.

Again it implies that "living" is involved, but it just says that a dye is added when it is manufactured. <"Manganese Violet"> would be both light colour-fast and non-toxic, or there are <"dyes for cement">.

Real Reef does not harbor nuisance or parasitic algaes, inverts and unwanted hitch hikers.

Same again, that just indicates it is a manufactured product.

So are these the same? But with one dyed purple and <"aspirationally priced">?

cheers Darrel

 

[tam]

There is a bit more info here: About us | Real Reef Rock.

In reef speak, live rock is basically the equivalent of getting a sponge filter from a running tank. It should be pre colonised by bacteria. Dead/dry rock is rocks that's been out the water or other conditions that aren't conducive to keeping the bacteria alive.

I don't know the exact process, but I would presume they make the rocks then 'farm' bacteria for several month prior to sale to make it live rock. The terms go back to when rocks came from the sea and live rock would be premium stuff shipped quick.

Other than the eco aspect the big draw is that the wild live rock came with the potential for all sorts of critters some of which could be problematic. Where as the artificial is pest free.

 

[dw1305]

Hi all,

In reef speak, live rock is basically the equivalent of getting a sponge filter from a running tank. It should be pre colonised by bacteria. Dead/dry rock is rocks that's been out the water or other conditions that aren't conducive to keeping the bacteria alive. I don't know the exact process, but I would presume they make the rocks then 'farm' bacteria for several month prior to sale to make it live rock.

Perfect, so kept in a bioreactor after "construction". This might offer some clues: <"Tim Hovanec's "Nitrification in marine aquarium" article">.

Original article at <"https://www.drtimsaquatics.com/wp-c...ification-in-Marine-Aquaria-3-parts-CORAL.pdf">

..... Contains 2X the available Alk, Calcium Carbonate CaCO3 and more available trace elements than wild live rock. Made by aquarists for aquarists. Developed over 19 years of research and feedback, we know what you want and we created it. ....... <"Real Reef Rock - Real Reef Solutions">

Interesting, definitely some cement in there somewhere, that is the extra alkalinity bit.

A truly green product, made from 11 natural Calcium Carbonate based materials and cultured for 5 months. Ideal bioactivity, without negative bioload and nuisance hitchhikers.

Well that explains the cost a bit more, it also says its light in weight. I'd love to know how they produce it.

cheers Darrel

 

[Tanksy]

I used live rock in my first SW tank many years ago. I tried to buy some for my new reef tank a few months ago, but no luck.
I went to a few lfs to check out their "live rock" and I found pieces full of algae. And the smell...ough! Real live rock smells like fresh ocean breeze.
Anyway, artificial reef rock is just painted and seeded with bacteria. And it takes so long to mature. Sometimes more than a year.
There are a few hobbyists claiming that their artificial rock leached some nasty suff in the water column. In most cases it was the cement that raised the pH and alkalinity.

But it's not the bacteria that makes the difference (by the way, the strains of bacteria that are found in the hobby is only a small percentage of what's in the sea).
It's the biome on live rock: copepods, amphipods, bristle worms, sponges, etc that are so beneficial in a reef tank. These are the first members of a clean-up-crew.
I was lucky enough to get a small piece from a fellow reefer and although I used Marco rock for the scape, it's so cool to see so many critters lurking on (and in) the sandbed.
The only place where you can find real live rock nowadays is either from Tampa Bay Saltwater, but there are no UK distributors; or from a donor with a reef tank that's at least 5 years old, as they'd most likely used live rock.

 

[dw1305]

Hi all,

It's the biome on live rock: copepods, amphipods, bristle worms, sponges, etc that are so beneficial in a reef tank. These are the first members of a clean-up-crew. The only place where you can find real live rock nowadays is either from Tampa Bay Saltwater, but there are no UK distributors

I wonder if you could age "artificial" live rock in UK seawater? I know that UK <"rock-pools can get fairly warm">, but still have <"coralline algae etc">. in them.

The scenario would be a bit like <"cultivation of Oysters"> in trays, or <"Nori on ropes">, but in this case the "crop" would be "maturing" reef rock.

cheers Darrel

 

[tam]

My parents recently redid their reef tank, replaced the tank they'd had 30+ years. It had wound down so they started from scratch but despite using artificial rocks still have bristle worms back again and alsorts of critters. I don't think it takes long to get going.