Product Review: Cermedia Marine Pure 8'x4'x4' Block in a 36L Saltwater Aquarium

Introduction

MarinePure(TM) by Cermedia is a product that has been around on the market for quite a while now, though only recently truly gaining a foothold. There are 3 versions of the product available in the Australian market; the 1.5" sphere, 8"x8"x4" block, and the 8"x8"x1" tile.

There are various differences between the different products. The sphere is in and of itself easier to distribute in an aquarium system, due to its relatively smaller size. Hence, it can be fitted into various areas of the tank/sump, without any modifications.

The tile and block are similar, though the tile is thinner - allowing for the insertion into tighter areas.

The block is harder in regards to placement, and is generally relegated fully to the sump, in contrast to the tile and spheres, which can and do find their way into displays where they are hidden by corals, plants, gravel or the likes. Of course, with a bit of creativity and planning, and/or a bit of modification, the block can still be placed in the display.

A 36L nano with 2 inches of Marine Pure hidden within the sand. The corals sit directly on top of it.

Background

Displayed above is my very own 36L nano. The sand fully hides the Marine Pure block, though I did cut it down the middle (making it 2' rather than 4'). Nonetheless, I am sure with a bit more effort, it won't be an issue. In a large tank, an entire Marine Pure block can be hidden amongst the rock work, for example.

Marine Pure placement revealed! And an Amphiprion melanopus chillaxin' in the corner.

Of course, if you happen to own something that loves to dig, prepare to have the block revealed (assuming you hid it in the sand). Here, my Amphiprion clarkii (not pictured) has decided to completely excavate the corner of the tank and reveal the Marine Pure. It is interesting to note that being the same color as the sand, it isn't quite that conspicuous.

Hidden in plain site. Can you actually tell the surface of the Marine Pure block from the sand?

But the ability to be incorporated into the display (or otherwise, in the case of the block), is just one of the factors to consider, and I personally care about the capabilities of the product.

Whilst all Marine Pure products (the spheres, tiles and blocks) are capable of denitrification, the blocks are said to be naturally better at it, thanks to the size and therefore deep, hidden compartments within. Most denitrifying microbes (not all) are anaerobic, therefore preferring/requiring anoxic environments. Therefore, it is recommended to place Marine Pure blocks (where you want denitrification to occur) in low flow areas, minimizing the amount of oxygen brought into the rocks. That or in the sand. This is why I placed mine in the sand.

I did cut out a 4'x4'x8' piece to place in my sump though.

Top view of the Marine Pure placement. The smaller, irregular piece sits on top of the 4'x4'x8' piece that takes up an entire compartment of my sump.

The placement here is essential for my build, as most of the flow is over the top of the divider. However, a slower movement of water does go under and up through the second chamber, which takes advantage of the anaerobic microbes within. The slow flow means less oxygen being driven through the block, but still enough to bring waste through it.

As a Biological Filter Media

So why all this talk about microbes, water flow and conditions of oxygen?

Marine Pure is a biological filter media. Amongst the scheme of filter media, Marine Pure is regarded by many as the most effective of them all. Between the three different categories of filter media - mechanical, biological and chemical - the biological media is the one that is regarded as the most long lasting, as it simply acts as a home for microbes that break down waste, the same as what happens in nature. Whilst mechanical filter media can be rinsed out until it is ruined, chemical filter media cannot, in any way, be rejuvenated.

The advantage of Marine Pure over other types of filter media is two-fold. The first advantage is that it does not degenerate, at least not as quickly as many other types of biological filter media. Ceramic noodles for example, can break down after 3-6 months of use, releasing tiny bits of itself into the water. The same can be said for many other biological filter media.

Live rock, the 'natural' biological filter media, do not suffer from such decomposition, but is not as porous as Marine Pure, which therefore is not as effective. It is often suggested that 30 kilograms of live rock is required for a 300 litre tank, whereas one block of Marine Pure can do the same.

Therefore the filtration capacity in my tank is in theory equal to 30 kilograms of rock. As for it's life expectancy, unlike many other biological filter media, there does not seem to be a point in time whereby the Marine Pure breaks apart.

Observed Results

At the beginning of the setup, I carried out an experiment whereby I added pureed marinara (seafood) mix in an attempt to completely go overboard with organics. I added approximately 20g of marinara mix in total, and within a day, it had pushed ammonia levels off the charts. The test kit couldn't even register how much ammonia is there, and the color change was something that I have never even seen before!

Within two days though, the ammonia levels have gone down considerably, closing in on zero. It was at 0.25ppm. The next day, it was gone.

No doubt, the sand would have helped as a biological filter media, but I can't help but attribute most of this to the Marine Pure. I do believe thanks to its large surface area that a lot of microbes managed to establish in a short time.

As for it's filtration capability post-cycle, I have a total of five fish, one large hammer and various corals in the tank. I worked out that I was feeding my fish 10x the amount recommended, and my corals 26x the recommended amount. Oops. Well the pictures above was taken when this was happening, and when I measured my parameters, well amazing, there was undectable ammonia, nitrite and nitrate.

Conclusion

Marine Pure is a highly effective, long-lasting biological filter media. The block is not cheap ($119.95 retail in Australia), but that's 95% less expensive than 30kg of live rock anyways. It lasts indefinitely as well, or at least that seems to be the case.

Here are my ratings for the product, out of 10:

• Price: 9, it costs quite a bit, but is sure worth it.
• Efficacy: 10, works wonders.
• Longevity: 10, for now anyways.
• Appearance: 7, it has a clean look to it, but may not fit in any tank.

Overall: 9, it is a solid (pun intended) product, that offers just so many benefits. I have found nothing that comes even close. Although it does cost quite a bit, it is an one-time purchase after all, and spending $199.95 per 300 litres of tank water isn't too bad. The only true issue in my opinion is its looks, but then again, with water circulators and all that in our tanks, it's not as if it matters too much if it looks 'artificial', eh?

Notes

-In Australia, Marine Pure can be purchased from most stores. Online, it can be bought from reputable sites such as Majestic Aquariums and Age of Aquariums.

-The distributor and supplier of Marine Pure in Australia is Majestic Aquarium's sister company, Aqua Premium. If you are a shop and want to consider distributing this product, contact Aqua Premium directly.

-Since this post was made, I have been told that this product seems to disintegrate at a low enough pH (at around 6.0). If anyone have anyone has conclusive results for this (tested it, found it to disintegrate at a certain pH/over a certain amount of time), then please do let me know by commenting below. I would love to know more about this. So far though, it seems to be safe at least at a pH of 7.0, so for reef tanks the Marine Pure products are at least still entirely viable.