Aquarium Chemistry: TDS

This column is an introduction to saltwater aquarium chemistry.  What better way to start this column than with an article on water quality.  It is generally easier to put clean water into an aquarium than to try to clean the water already in the aquarium.

How Clean is “Clean”?
First, a definition of TDS is in order.  TDS is a measure of the “total dissolved solids” in the water.  This measurement is easily accomplished with a simple hand-held device starting at a cost around $20 (U.S.)  Basically, it just gives a number to how many particles are not water.  The EPA (Environmental Protection Agency in the U.S.) states that a TDS reading of more than 500 is not suitable for human consumption.  Most bottled water is around 100-300, and tap water ranges greatly based on location and house plumbing.

Although there are some aquariums out there than run successfully on dechlorinated tap water, it is generally not recommended in the hobby.  Contaminants like copper and excess nutrients may be left in the water to pollute the aquarium.  Properly distilled water purchased from grocery stores may work fine, but it is possible that the water was processed in copper tubing.

The most recommended sources of clean water are either purchased from a reputable aquarium store or from a home reverse osmosis de-ionizing unit (RO/DI).  With regularly changed filters, the TDS from an RO/DI should be zero.  The TDS of saltwater and aquarium water is beyond the limits of inexpensive hobbyist grade meters.

2 pings

  1. How to Mix Saltwater » Reef'd Up Aquatics

    […] 5.  I highly recommend using reverse osmosis deionized (RO/DI) water, but I have seen successful reef tanks that have only used RO water or even de-chlorinated tap water.  You’ll need enough for your water change.  For more information about RO/DI systems and water purity, see a basic tutorial here. […]

  2. Aquarium Chemistry: Salinity » Reef'd Up Aquatics

    […] « Aquarium Chemistry: TDS […]

Leave a Reply