Great gads, one of the most-overlooked yet pivotal issues directly related to your success in most aquatic endeavors! Some systems may be more forgiving of water quality mistakes than others, i.e., freshwater versus marine, fish-focus versus reef, african cichlids versus discus--but you shouldn’t look at it this way. Your goal should be to provide the best environment for your captive life, period. This means starting with the best quality water possible.

One of the most effective and, in the long run, economical ways to obtain good quality water is to purchase a quality RO/DI unit. When maintained properly, these units remove any toxins of concern from tap water. The water produced by an RO/DI unit is “pure” in the sense that you start from zero/nothing and add to it any conditioners required to maintain a particular type of ecosystem. This means marine salt for marine systems, cichlid salts and buffers for cichlid systems, electrolyte-replenishing substances for various freshwater systems, etc. This water should be used whenever you perform water changes or evaporative top-offs. It should be the only water to ever go in your tank.

We only recommend the use of Full-size TFC RO/DI units. It is not necessary that you understand all the intricacies of how RO/DI filtration works. But you must maintain the unit to maintain optimum water quality. A brief understanding of how such a unit operates is necessary to do this. First, tap water enters the unit and goes through a sediment prefilter. This removes larger sized contaminants in the water, i.e., rust, dirt, etc, that would quickly clog later components of the unit. Next the water proceeds through a carbon prefilter. This unit removes smaller highly charged particles in the water, the most important of which is chlorine for our purposes. This is very important because TFC RO membranes are destroyed upon prolonged contact with chlorine ions. After the carbon prefilter, the water is then passed through the actual RO membrane. Here the water is stripped of all but the tiniest of particles. This is the workhorse of the unit. From the membrane, the water then goes to a deionization postfilter. Here the water is polished by final removal of tiny charged ions. When the water leaves here, with a properly functioning unit, you basically have pure H2O.

Now you understand the water path through the unit and the importance of each component.. Although tap water varies in its chemical make-up across the U.S., unless you have horrendous ground water (and you probably already know if you do), the various components of the RO/DI unit described above should be replaced on the following schedule:

Sediment Prefilter... Every 3-6 months ($8-10)

Carbon Prefilter... Every 3-6 months ($18-22)

RO Membrane... Every 1-2 years ($80-130)

DI Cartridge... Every 3-6 months ($25-40)

The lower figure if you are generating the full daily capacity of the unit more than three times per week OR you know your local water supply is high in ions, macro particles or other such contaminants. The higher figure if neither of the preceding conditions are met.

THAT’S IT!!! Now you too can have the highest water quality. As an additional step to preparing any water for addition to your system, we recommend that you add any conditioners, including salt, and aerate (airstone, airline tubing and an air pump) the water for at least 24 hours before use. Rubbermaid or Naglene containers are great for storing and mixing system water.

Do not use distilled or bottled waters. You don’t know if the distillery or manufacturing process involved the use of copper tubing or any other additives that might be okay for us but not our aquatic friends.