Who do you believe!?

[K-Holed]

I've been looking round the LFS's today, looking at setting up a marine setup.

I decided to get some general opinions on the best way to set up a smallish system (10-20 uk gallons or 12-24 Us gallons)

One place pointed me a Juwel aquarium of around 20-25 gallons (uk). They suggested initially using the internal power filter and the two lights supplied, if I wanted to keep a mainly fish only system. they also mentioned that movement is very importent in the water and it may also help to have a small under gravel plate with 2 powerheads on to create more movement and also utilise the substrate by drawing the water through it and helping to buffer the water. This all didn't sound too silly or off the mark. the next thing I asked about was live rock/sand ... to which they ansered ... don't bother. They said that it was unnessercarry.

My question (finally!) is IS live rock really needed. I don't have an opinion either way having not kept marine fish in my own home. Some people seem to think it is esential, others seem to think it is not. The LFS which I used to work in NEVER used live rock and they have had a reef seyup there for over 3 years and it's healthy and full of life. I don't know whether this diference of opinion comes because of me coming from the uk, but it seems that all the LFS's I have been to don't seem to think it's nesercarry or even desireable compared to most people I have spoken to on various forums from the US that swear by it!!!!

Sorry for the long and rambling post, but I'd really like some closure on this before I start putting a system together.

James

 

[Navarre]

Hi James

You question isnt stupid and is a very good one at that!

No, live rock is NOT essential.

However....

What other type of filtration will you use? Undergravel filters? Vey old and not very reliable anymore.
Trickle filters? very good filter and highly recomended.
Fluidised sand bed? I have one of these and they are brilliant for removing waste aterial.

And the list continues but they all have 1 thing in common. They cannot complete the denitrifying cycle.
All the above filters will turn ammonia to Nitire and even turn nitrite to nitrate but thats where it stops. How do you remove the growing nitrate problem? water changes...

Live rock however does the whole job for you (ok also minerl mud systems with algea also does this). It will turn nitrate into harmelss NItrogen and release it into the atmpshoere safely.

You also have to fill your tank with some sort of rock or decoration so why not kill 2 birds with 1 stone and have a great looking tank as well as the best filter that nature designed..

You can run a marine tank without live rock but if you want a fully diverse reef, teeming with life and colour then live rock is essential!

Hope this helps.

 

[K-Holed]

Thankyou for your prompt reply. What is it exactly that the live rock contains that completes the nitrogen cycle? Is there some bacteria there that is ot present in a traditional filter system?

 

[Navarre]

Good Question!

OK lets see if i can put this into a format i can understand

Man made filters are very good at making nitrates. If you have kept fish before you will be aware of this of course. Now to create nitrates you need bacteria that live in an oxygen rich environment.

So...

Lets look at a fluidised sand bed. It used sand and moves it in a colum of water that of course is oxygen rich. Great for bacteria that produce nitrates.

Trickle filters, they do the same (though they are better because they use the oxygen in the atmosphere rather than in the water so the fish dont have to compete with the bacteria.

This is the same (or similar) with all filters no matter what the type.

Live rock is unique (i wil talk about algea in a moment) becaus eof the way its made. Live rock is porous and you will see this when you take it out of the water as it lets water flow out of it for quite some time.

Now...

The surface of the live rock is great for oxygen rich bacteria that produce nitrates. This bacteria will penetrate the rock a little way in but soon stops. Its what lies deep inside the rock thats most important!

The water will pass through the live rock very slowly, as it does so, the surface bacteria will use the oxygen in the water to creat the nitrates. As the water (now oxygen poor) travels through the rock with the nitrates. A new form of bacteria exsists. This bacteria can only live in oxygen poor environments. What it does then is to use the nitrates to break down into Nitrogen. Only live rock can produce this unique effect of a low oxygen environement.

This is the beauty of live rock and why its so valuable. The ocean (and nature) has found a superb way of controlling the waste of the inhabitants of the ocean. Man simply cant compete with this

Ok now i will address the algea situation.

Algea is another way of breaking down Nitrates. When you see huge algea blooms in your tank (usually hair algea) ths is a sign of high nitrates or phosphates. Algea will consume nitrates in order to grow. Now if you can get a good looking algea (there are a few out there) then its posible to control NItrates this way.

In fact in my main tank i have live rock for the main filtration, in my sump i keep various algeas to help consume any extra nitrates that are produced. I will soon be adding Mangroves in the sumop also (these plants also extract nitrates but are not very practical to put in your tank of course).

Hope this helps a little.

 

[K-Holed]

lol more than I needed but thankyou. I guess the bit I wanted to take form that is the fact that there are anaerobic bacteria present in the tank to complete the nitrogen cycle. I've heard of this being done in some filters before but hadn't considered the possibility of it being done withing the tank.

I don't know whether you are aware of a rock called 'tufa' rock. This is one of the rocks I used to use in my brackish setup. It is a VERY porous rock. It's hard to describe ... It's kind of like a very hard dense sponge made out of chalk ... ok that's a bad description but you get the point. Do you think that this would yield a similar effect over time?

Here's a picture

 

[EddieW]

Tufa rock is not really recommended for a marine setup as it is too soft. Coralline algae does not establish itself very well on tufa rock.

 

[K-Holed]

What rocks are usually the base for most of the live rock harvested then?

 

[Navarre]

Tufa rock was very commonly used about 8 years ago when i first started keeping marines but it soon became apparant how poor it was for a marine setup.
Tufa rock is a bit too porous and allows water to pass through too fast. More importantly though, its also very good at absorbing things. This means it is capable of storing chemicals, medications, phosphates etc etc.

At some point this rock will rech saturation point and then its possible that it will sudenly leech these unwanted good back into the tank and harm the fish/inverts. The main problem with it was when people dosed with copper then much later they would clean the system out and check for copper left in the tank. It would show a reading of zero and people felt it was then safe to add inverts. Then a few months down the line the tufa rock would leech the copper back into the tank and kill the entire reef!

Live rock is far superior and the amount of biolife that live on and in the rock is amazing! i spent hours just watching a bunch of rocks when i first had them to see what life had came with it. Even months later i am still finding life that i have never seen before in the tank and this is all thanks to live rock.


Live rock is the bones and remains of reefs gone by. old reefs die off and are crushed into sand, its then bound together making a rich calium type of sandstone thats very strong (at least that is one of the ways).

You can get man made live rock but to be honest its hard to get the right porousness (spelling!) of it and you wont get the biodiversity of life. Just a rock that can filter.