Revering Reverse Osmosis

Posted by Aquatropic Staff on May 3, 2024

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The small glass boxes we fill with water and aquatic critters are microcosms of larger environments. They keep up endlessly captivated and engaged with their health and aesthetic. When we look at these small displays, we don't often process that the overwhelming majority of what we see (or at least look through) is water. We talk about the plants, the fish, the inverts, we even talk about the sand, the rock and what species of tree the wood came from. What we rarely talk about but is vastly more important than all the rest of that stuff combined, is the water, how we source it, and how we filter it.

Maintaining optimal water quality is paramount for the health and longevity of our aquatic system's inhabitants and this starts with having a clean water source before it ever reaches the aquarium itself. To this end, we're going to explore reverse osmosis filtration (commonly called R/O) and its application in freshwater aquariums. While not applicable to the filtration of the actual aquarium, it has no equal when we talk about how to purify the water before it gets into the tank.

The best place to start with Reverse Osmosis is: what exactly is it? To understand what is going on here, you need to understand the concept of a “semi-permeable” membrane. Envision a sheet of filter paper that can let water through, but nothing else. In a world where there is water at equal pressure on both sides of this filter paper, the pure water will always “want” to go toward the side that has more dissolved minerals, a process called osmosis. Reverse Osmosis is a process wherein pressure is added to one side of this membrane to force water away from the more concentrated side. The end result is a solution that is more concentrated on one side of the filter, effectively purifying water by trapping contaminants and yielding clean, potable water on the other side of the membrane. This is not a 100% efficient process as we can't force all the water through, so some water is “wasted,” and all the water left on the dirty side gets rejected. Often times this “reject” water is clean enough for other purposes. The efficiency and effectiveness of this process change based on the permeability of the membrane that is used. An easy way to envision this is to think of permeability as the size of the holes in the filter paper we imagined above.

So, what are we trying to accomplish by making water this pure? Well, the technology was originally designed by a UCLA scientist, Sidney Loeb for making clean drinking water from sea water. In the realm of freshwater aquariums, the threshold for what we are removing from the water is slightly different, but water quality is still paramount for the health and vitality of aquatic life. Tap water, although frequently delicious and impressively clear, often contains impurities, some of which can be detrimental or even toxic to fish, plants, and invertebrates. Reverse osmosis filtration serves as an indispensable tool for aquarists, enabling us to have a starting point where we know exactly what is in the water going into our system... nothing.

Chlorine and chloramines, commonly found in tap water, are added as (very efficient) disinfectants but are most often toxic to aquatic organisms. Reverse osmosis filtration effectively eliminates these chemicals, along with heavy metals such as lead, copper, and arsenic, which may leach into water from plumbing systems or are sometimes present in well water, safeguarding against potential poisoning.

The next portion of this process to understand is the reduction of Total Dissolved Solids, often abbreviated as TDS. Total dissolved solids encompass various organic and inorganic compounds present in water, including minerals, salts, and other dissolved substances. While some minerals are beneficial in moderation, excessive TDS levels of some compounds can lead to water hardness and mineral imbalances detrimental to specific invertebrates and even fish. Reverse osmosis filtration effectively reduces or even eliminates TDS levels, providing us with a clean slate; total control over water chemistry enabling us to create ideal conditions for our aquarium inhabitants.

Water hardness and pH are directly tied to TDS through the dissolution of a variety of mineral compounds. Maintaining stable pH and water hardness levels is crucial for the health and wellbeing of many freshwater species. Both these water quality parameters can be directly tied to some species willingness to spawn and the success of that reproduction as well. Reverse osmosis filtration allows aquarists to start with a blank canvas, devoid of mineral content, enabling precise control over water parameters through the addition of supplemental salts, minerals and pH-adjusting compounds.

There are other benefits too. Many places have elevated levels of nitrogen and phosphorus in the tap water. While the levels present are nearly always harmless to humans and usually fish, they can help fuel nuisance algae blooms, which can be extraordinarily frustrating when you don't realize that the actual water source is the culprit in why you can't manage the algae breakout in your display!

One of the best things you can do, as an aquarist of any level, is to start your aquarium with water that has been filtered with a reverse osmosis filter. To this end, we offer hobbyists (through our retail partners) a high-quality line of home sized R/O filters from Tropical Marine Centre called V2 Pure. Don't be put off by the “Marine” in the title of TMC, these are quality units, perfectly suited for your freshwater aquarium. The V2 Pure 50 is capable of producing 50 US gallons of pure water every day while the V2 Pure 100 can (predictably) produce 100 US gallons per day. Both are fitted with mechanical filtration, carbon filtration and a pressure gauge in addition to the R/O membrane. The V2 50 Advanced and the V2 100 Advanced also integrate a Total Dissolved Solids Meter so you can better monitor when it is time for maintenance or replacement of your R/O membrane. In our often-intricate realm of freshwater aquarium keeping, the significance of water quality cannot be overstated. Reverse osmosis filtration stands as a cornerstone technology, empowering all aquarists to create and maintain optimal aquatic environments for our cherished aquarium inhabitants. By purifying water and eliminating harmful contaminants, RO filtration not only promotes the health and vitality of aquatic life but can also unlock the potential for breeding success. The TMC V2 line has our highest recommendation and we're happy to be able to supply them to our retail partners. If you do not have the capacity or space for your own R/O unit, many local fish stores offer reverse osmosis filter water for sale and this is also an excellent pathway to clean, pure water for your aquarium. Head over to your LFS and ask them about getting you a TMC reverse osmosis filter from Aquatropic today!