I have experienced all phases of marine aquarium keeping. From the era of undergound filters where products were added to promote algae growth, to canisters, dry wet, live rocks, DSB, ETS skimmers with bioballs, airstone skimmers, recirculating skimmers, pinwheel skimmers, bubble plate skimmers, phosphate media, ICP testing, etc. In other words, the
market is always looking for the Columbus egg, the holy grail and, obviously, profit, because no one is a charity.
What I think:
-Underground filters really worked, as the area for bacteria was huge and the circulation rate using powerheads was greater than with airstone.
-Nitrate factory does not exist. Every biological system that works will generate nitrate. If it doesn't generate, it's because the cycle isn't closing. Perhaps this myth came about when they exchanged dry wet for live rocks, after all, dry wet was excellent for the biological cycle and live rocks were much more limited for that. Therefore, with dry wet you could have more biological load. In one of live rocks, the load had to be smaller to avoid ammonia/nitrite, so the final nitrate was also smaller and could remain undetectable, as it is consumed (even through bioassimilation) by other organisms, such as algae, Zooxanthellae, calcareous algae, etc. In fact, this is how the main marine aquarium at the Düsseldorf Aquarium was maintained. It didn't have a skimmer and just a giant calcium reactor created by Daniel Knop and was based on the filtration that calcareous macroalgae performed. Especially because it is impossible to occur anaerobic denitrification in aquariums according to several tests that have already been carried out in reefkeeping and advancedaquarist.
-Algae are something natural in an aquatic system (I'm not talking about a eutrophication situation).
-Colorful corals devoid of symbiotic algae that create a pigment to protect themselves from light are not normal in nature.
-Combining the two things above, we are always struggling to have an aquarium with situations that are not natural. Going against entropy is difficult. The same thing applies to planted aquariums that are not natural. In nature, most plants are not 100% aquatic. They only spend a cycle of their life in water.
-According to various literatures, part of what a fish eats is used for growth (body mass) and/or to stay alive. The rest is expelled. We have nitrogenous or non-nitrogenous organic compounds. Fish excrete ammonia directly from their gills and in the form of urine. In other words, there is no way for a skimmer to remove “this” before it enters the nitrogen cycle, as they say. Some authors quantify that approximately 70% of the ammonia is expelled through the gills, 20% through urine. The other 10% would be in the feces, still in the form of particulate nitrogen compounds. In other words, if we remove the feces in time, and/or leftover food (which should not be left over), we would be relieving the biological filter by only 10%. That is why an underground filter works. Not to mention that the decomposition of feces and/or leftover food is very fast. Therefore, mechanical filtration should be very fast both to remove it from the aquarium and to clean the filter, not leaving these residues in contact with the water inside the filter. Remember that a canister filter can remove these residues much more easily than an aquarium with only overflow, even if you use a bare bottom and exaggerated internal circulation. Unless you use siphons, which is not at all practical.
-In addition, we have non-nitrogenous organic compounds that are partially removed by the skimmer. They say it is around 35% or a little more. In other words, there will always be organic compounds in the water, and those that are added to the water. One way to eliminate these organic compounds would also be with biological filtration, but much more intense than the biological filtration used to eliminate ammonia/nitrite. Remember that these compounds also somehow favor the appearance of algae. That is why people do not understand how there are algae even with zero phosphate and nitrate.
-In tests, a substrate that does not have an underground filter also performs biological filtration depending on the oxygenation level in the aquarium. Although it is very limited in this function. A live rock would then be even more limited, not to mention that the pores would quickly become clogged (like ceramic and glass filter media) with the gelatinous mass that the bacteria create when reproducing.
-Oxygen level is best achieved with airstones (which no one uses) and skimmers. In fact, I think (completely my own thought) that the skimmer's greatest use is aeration. And I have some doubts (I never found an answer) whether the skimmer would be able to remove some ammonia from the water through air stripping like in some water treatment plants.
-Combining the above, the standard aquarium today is more or less like this:
1- Uses a skimmer;
2- Does not have a dedicated biological filter, as they rely on the substrate and live rocks;
3- Water (and solid waste) is collected only through overflow;
4- Aims to not have any algae or corals with unnatural colors.
In other words, a very difficult hobby since we look for situations that escape entropy and use undersized filters for this.
In short:
-We want an aquarium with an unnatural appearance;
-We don't use a dedicated biological filter or a biological filter that quickly clogs the pores;
-We don't even come close to having a biological filter capable of processing non-nitrogenous organic matter;
-We don't have good solid waste collection, although this doesn't really matter, as mentioned above in the section on ammonia release by fish;
-We always look for the miracle product;
-We prefer to post photos of the equipment rather than the display;
-The
market knows all of this and bombards us with dozens of miracle launches.
So, we will always run away from the intended goal, in the wrong way and spending many thousands of dollars in an endless race. That is why we still need to change water even with all the technology available. After all, it is still the easiest way to correct what is wrong when the system cannot handle the problem. Just look at planted aquariums that face the dilemma of not being able to have much circulation because of the CO₂ level. As a result, there is not enough filtration in the planted aquarium, not even for the nitrogen cycle, let alone to remove non-nitrogen organic compounds. That is why the life of a planted aquarium aquarist is to change water like crazy and only have two 5 mm fish.
In time: If it is difficult to imitate nature in a closed system, imagine trying to create an unnatural nature that not even nature can achieve within a closed system.
Not to mention when we mix organisms from completely different biotopes.
