The purity of the water you use in your aquarium has a dramatic effect on the stability and success of your reef tank. Reverse osmosis and deionization systems are pretty much considered essential for keeping a reef tank today. But how do you know that your water purification system is actually working? Sure, you can test for a few parameters like phosphate and nitrate but that won’t give you an overall picture of the water purity.
Water filtration professionals use TDS or “total dissolved solids” testing to monitor how well a water purification system is performing. TDS is the measure of all the dissolved minerals, nutrients and salts in water. A properly functioning RO or DI system should reduce the TDS level by at least 90%.
As the RO membrane ages, it starts to allow salts, nutrients and metals through. The same happens when deionization cartridges near exhaustion. When this happens, the TDS level gradually rises. The HM Digital TDS Meter measures the TDS of the incoming water and the purified water, giving you a complete picture on water quality
Here’s how it works:
- Connect the incoming water line to the IN fitting.
- Connect the filter outlet line to the OUT fitting
The meter monitors TDS before and after your RO/DI system. Select IN or Out with the switch and the meter will display the TDS in parts per million.
Let's say your tap water has a TDS of 200 ppm. After passing through the RO the TDS is 20 ppm. That’s a 90% reduction and means your RO system is working properly. When the TDS begins to creep up in the purified water you know it’s time to change the RO membrane or DI cartridge.
The real strength of the meter is that it tells you in real time that the water your adding to your reef is safe and won’t cause an algae bloom or degrade water quality.