Drs. Foster & Smith Educational Staff

How to Use Reverse Osmosis in Your Aquarium

How to Use Reverse Osmosis in Your Aquarium

In the pursuit of providing the best water quality for your aquarium, you may find that the water coming out of your tap just does not have the correct parameters for your aquarium's inhabitants. Plain tap water can even contain toxic chemicals. One simple solution to this problem is to use a Reverse Osmosis (R.O.) unit to purify and soften the water.

How does Reverse Osmosis work?

Using the simple principle of applying a pressure gradient to a semi-permeable membrane, you can eliminate most of the chemicals found in the tap water and produce pure water. The semi-permeable R.O. membrane only allows very small molecules (such as H2O) to pass through it, effectively removing 90-99% of most water impurities including pesticides, arsenic, and heavy metals.

What are the benefits to using an R.O. system in freshwater tanks?

Freshwater Aquariums

For freshwater applications, using an R.O. unit will provide water without General Hardness (GH) or Carbonate Hardness (KH). This allows the addition of trace elements and electrolytes to match the natural water conditions of the fish we keep. The removal of the KH allows use of buffers to easily set the water's pH wherever you wish. This is great for plants and soft water loving fish like Discus and Angelfish.

The importance of maintaining your R.O. unit

Performing routine maintenance on your R.O. unit will ensure high quality water production and will extend the life of your unit. Replace sediment pre-filter and carbon block based on manufacturer recommendations or as soon as you see noticeable discoloration, reduction in production or drop in water pressure. Replace the R.O. membrane per manufacturer recommendations or use a TDS Meter to monitor its performance. Keep in mind, the quality of your source water will determine how often you will need to replace each component i.e., areas with greater quantities of dissolved solids and impurities will require more frequent changes.

Overall, R.O. units definitely benefit your fish and plants by removing impurities in your source water. Knowing what types of impurities your water contains helps you determine the best R.O. unit for your aquarium.

Simple reasons to use an R.O. unit:
  • Provides softened water, removing GH or KH, which allows you to adjust the pH to match the water parameter requirements of your fish.
  • Eliminates possible toxins and other unwanted compounds from your water responsible for poor water quality and unsightly, cloudy aquarium water.
  • R.O./D.I. units remove any phosphate or nitrate that passes through the R.O. unit, reducing algae fueling nutrients.
  • • R.O. water is perfect for topping off the aquarium's evaporated water.
  • R.O. units easily connect to most faucets, and some contain automatic shutoff valves that stop source water flow once the collection reservoir is filled.
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