How to Make Your Own RO System

Many salt water hobbyists mix synthetic sea salt with water to duplicate ocean water. Although readily available, tap water typically contains chlorine, phosphates and nitrates. Aquarists therefore often use reverse osmosis (RO) units, which contain a semi-permeable membrane, to purify the tap water. It is possible to make these units more effective by prefiltering the water through a micron filter and activated carbon before passing it across the semi-permeable membrane. Tap water needs to be forced through the membrane under pressure and much water is lost during the process, but the collected filtered water is normally very pure and free of contaminants.

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Tap water contains contaminants that are unsuitable for fish.

Remove the lid on the micron filter cylinder and insert the filter cartridge. Ensure that the gasket is positioned correctly in the lid and screw the lid back on the cylinder. It is very important that a gasket is present and that it is not twisted during the sealing process, as the tap water will be under pressure as it passes through this cartridge.

Remove the lid of the semi-permeable membrane cylinder and insert a membrane cartridge. Ensure that the gasket is positioned correctly in the lid and screw the lid back on the cylinder.

Remove the lid of the activated carbon cylinder and insert the activated carbon cartridge. Ensure that the gasket is positioned correctly in the lid and screw the lid back on the cylinder.

Screw the reverse osmosis tap connector onto a tap and attach one end of the 0.9-inch diameter connector tubing to the tap connector.

Attach the opposite end of connector tubing to the first arm of a “T” connection and the opposite end of the tubing to the intake nipple of the micron filter cylinder. Attach one end of a 6-inch long piece of 0.9-inch diameter tubing to the outflow nipple of the micron filter and connect the opposite end to the inflow nipple of the activated carbon cylinder.

Connect one end of a second 6-inch long piece of 0.9-inch diameter tubing to the outflow nipple of the activated carbon cylinder and connect the opposite end to the inflow nipple of the semi-permeable cylinder.

Connect one end of the 4-foot-long collection pipe to the outflow nipple of the semi-permeable membrane cylinder and place the opposite end in a clean 25-gallon plastic bucket.

Connect the one end of 50-foot exhaust pipe to the third arm of the “T” connection and run the opposite end into a water collection vat, or out to the flower beds or lawn.

Turn on the tap and close the inline plastic tap that leads to the 25-gallon bucket and open the inline-plastic exhaust tap. Turn on the tap fully and wait for three or four minutes while the cartridges are flushed out.

Turn off the tap. Close the inline plastic exhaust tap and open the inline tap in the 25-gallon plastic bucket.

Turn on the tap and allow the bucket to fill with pure water.

Close off the tap once the bucket is full.