over time have been discovered many techniques for filtering aquarium water each with its advantages and disadvantages, and each suitable for a particular type of aquarium.
The filters are divided into filters, oxidizing, reducing, mechanical, chemical, natural.
The biological filter, trickling filter, the filter under sand filters are oxidants that through the action of certain bacteria living in the aerobic (with oxygen) convert the ammonia (NH3) into nitrite (NO2) and the latter into nitrate (NO3) will multiply in the aquarium water, reducing in the absence of a filter. The first two are much more toxic than the nitrates and should be kept at very low concentrations, while nitrates are tolerated by many species even at relatively high concentrations.
In freshwater aquariums or fish only, in some cases, can be tolerated even at concentrations of 100 mg / l (although you should never reach such values).
Generally this type of filter is used in aquariums or in the marine fish only, but if we want to raise even invertebrates (in especially if tropical) we should keep them at much lower concentrations, below 30 mg / l.
Clearly these are not optimal concentrations, but merely tolerated, and then we should try, again, we are making any kind of aquarium to keep the nitrates also close to 0 mg / l. The
reducing nitrate filter is a filter, which is that, thanks to the action of anaerobic bacteria (living in environments with low oxygen concentration), reduce nitrate (NO3) to nitrogen gas (N2) and volatile returns being free atmosphere.
It 's a filter that generally works with the addition of organic carbon sources, such as alcohol alcohol or sulfur, and are quite delicate to handle and therefore suitable only for hobbyists who already have some experience and familiarity with chemistry.
If the flow into the reductor is too slow it will create an anoxic environment and become free in our aquarium, sulfates, which are highly toxic. How
mechanical filters have activated carbon adsorbent has a power that serves to remove water and coloring matter, phenols, toxins released from invertebrates residual traces of drugs and many other harmful molecules dissolved in water. Along with these substances are also removed many other important elements like iodine, which therefore must be reinstated, if you constantly use of activated charcoal.
Another mechanical filter is the Perlon wool that keeps the particles suspended in water and that there should be used before any other type of filter and washed or replaced every week to prevent it from turning into a biological filter and "produce" nitrates.
In the category of mechanical filters is part of the protein skimmer (skimmer). This, too, such as Perlon wool removes particulate matter before it turns into nitrates and phosphates, but without the risk that even a small part of what has already removed going to pollute the aquarium water. How
chemical filters have the ion-exchange resins ion-trapping harmful (such as phosphate ions) and release ions in water are not harmful.
Another material is the zeolite filter function that has both chemical (ion exchange), but in the marine aquarium loses much of its effectiveness due to the high concentration of sodium ions (Na +), which function as the activated carbon adsorbent .
addition to these filtering systems, we have a series of natural filters.
The filter has the function of keeping algae low concentrations of nitrogen and phosphorus are absorbed by algae. It consists of a pool lit up for 24 hours with 24 in a large amount of algae growing as fast Caulerpa or Chaetomorpha to be pruned regularly to remove nutrients.
These grow to take advantage of the phosphates and nitrogen compounds dissolved in water. The filter
DSB (deep sand bed) and the filter function have Jaubert oxidizing and reducing the surface layers and deep layers of filtering systems are very natural and full, very suitable for setting up aquariums.
also live rock, if not sufficiently porous, with pores too large, can play a good role reducing (to them) as well as oxidant on their outer surface and superficial.
