TDS Monitor

Most reef aquarist highly recommend that evaporating aquarium moisture be replaced ("topped off") with RO (reverse osmosis) water. And, a TDS (total dissolved solids) monitor should be used to test the quality of RO water being produced over time. Part of the goal is to avoid adding water containing trace contaminants (ammonia, nitrates) and chemical additives (chlorine/chloramines) which may be detrimental to the inhabitants of your aquarium. The other part is to know when you absolutely must replace the cartridge filters on the RO unit.

Last August, I ordered this in-line TDS Monitor for my water purifier and finally came around to plumbing it in. Having dual conductivity probes allows one to track TDS for input and output water quality.

Looking under the kitchen sink, I discovered that the RO unit was being fed with a 1/4" line while the other lines, including the output, were 3/8". Unfortunately, the TDS Monitor was only supplied with two 1/4" Quick Connect tees.

To solve the problem, I bought two 3/8" to 1/4" coupling adapters from Home Depot and inserted 1/4" line to join them to the supplied tee. I found one website that offered other sized fittings with this kit, but I'm unsure on how they address the fact that the probe is still 1/4". Maybe they provide a simple adapter to cover the probe?

Here's the final look. I haven't activated the double-sided tape on the back of the monitor, yet.

Current Reading

Input (water softened) : 462 ppm

Output: 9 ppm (<10 is recommended)