Vertex ROX-8 Active Carbon
by
jellyfisch » Fri 15 Feb, 2013 9:12 pm
Although this is not a new product from Vertex, I do get many questions concerning it and carbon in general. Thus, a short epistle on carbon, why you should use it and what seperates Vertex ROX-8 from the competiton.
It seems like it has always been there, active carbon, formely just called aquarium charcoal (if you remember this, you are dating yourself!), the product was religiously added to your filter and held in place with some spun polyester (or similar). We've come a long way since these primitive filters and active carbon has evolved over the years to a regular plethora of products of variing qualities and worth.
Just what is active carbon? Simply put, it is the result of heating organic matter, typically a lignin, such as wood, nutshells, etc. to a point where it actually takes on a crystaline structure. There are a few methods used and they have individual results allow for specialization on a commercial level, but the end product is similar. A fine pored matrix with an ionic charge.
The ionic charge is important, as this is what gives carbon its especially effective filtering qualities. It attracts and adsorbs organic molecules from the water column. Adsorbtion is a chemical process whereby the positive and negetive ions bind to the filtering structure. They become strongly attached and do not easily release from the matrix. This differs from absorbtion, where the matrix simply holds the filtered matter within its structure, as we see in a spong. It may be wrung out and the material is released. Not so by adsorbtion.
Filter carbon has both of these properties making it very usefull.
Typical organics in a marine tank are protiens, such as amino acids and other organics, one group of which we refer to as gelbstoff (german for yellow material). This group of wastes colours the water, as well as being a chemical pollutant. Other materials removed by activ carbon are methylene blue, iodine, chlorine and many medications. Nitrates, phosphates and metals are NOT removed with active carbon. They generally have the wrong ionic charge (positive) and do not bind.
OK, those are some basics, but what makes Vertex ROX-8 so special and usefull? Here we come to the final properties of active carbon types. First, let's consider skeletal density. This refers to the porosity of the carbon. ROX-8 was developed by the company Norit for fine filtering in the food and medical areas. A fine porosity is important. Plus, the extreme hardness of the carbon plays an important role. Being a low abrasion carbon, there is little dust. ROX-8 has a surface area of over 1225 sq meters per gram!
Purity. This is important for marine systems for some obvious reasons. When carbon is made, if the carbonising process is not complete, you may have residues in the matrix. Typically, phosphates are associated with this process in low quality carbons. Contrary to belief, residual phosphates are not from the acid-washing process used in better carbons. For this washing nitric acid or hydrochloric acid are used. Yes, ROX-8 is acid washed and pH neutral. This neutral pH is a good indicator of the purity of an active carbon.
Another factor is the ash content, which is a by-product of the carbonising containing much iron, thus promoting algal growth, if present in large amounts. A level of up to 3% is acceptable and will not promote alga.
These criteria should be listed on the label of the active carbon. If not, one should ask themselves why.
How does one know, if these levels are maintained in a carbon. Unless the product is subject to regular inspections via a certified lab/control organisation, you cannot be sure. As this product is partially destined for the medical and food branches, Vertex ROX-8 is inspected regularly and certified by the British Standard Institute. It is FDA approved.
Using active carbon of this high a quality should follow some simple guidelines. As it is extremely effective at removing organics, we recommend using it for only 3 days per month as a filtering cure. Here there are two grounds: first, the carbon tends to be ionically exhausted in about 3 days in a marine system. After this period the carbon is only really effective as physical filtration (absorbtion), although it will still have some ionic properties. Secondly and following this thought, one should refrain from dosing organic to the reef, such as amino acids, as they will be quickly removed by the carbon. Both a waste of aminos and filter material! Removing the carbon after it has done its work assures that dosed organics are reaching their users.
Some do prefer to run carbon passively in a sock, placed simply in the sump aways from strong flow. The idea is that the effect is gentler. Frankly, I do not see this as being adventageous, as the sock needs to be massaged daily (more work) and it will be removing a part of the desirable organics at any given time. In short, I prefer to run it actively for 3 days once per month and basta! In the end, it is your choice. Both approaches seem to work well.
NOTE: always rinse your carbon before use! All carbons will contain some dust. Some horrifiing amounts (try to avoid them). If the carbon does not hiss and absorb water in an otherwise almost loud manner, it is not top quality. This hissing is reflective of the surface area (skeletal densitiy).
A word on HLLE (Head and Lateral Line Erosion). This has been associated with active carbons. I can tell you, from my own experience, there is a clear association and the effects on a tank may be devastating, especially for Acanthurids, Pomacanthids and fine-skinned Pomacentrids (clown fish). Although there is no lab evidence that carbon dust is the culprit, cheap carbon products are closely associated. In my own tests, those carbons that caused outbreaks were, despite their appearances, relatively inexpensive and dusty, typically without much on the label as to quality (not always, however). I cannot prove it, but, I do not think the dust is directly the problem, rather something in the carbonising process and the dust may exacerbate the situation or act as a carrier.
Jamie Vande
Customer Support Ver
tex Aquaristik