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How to Re-Pressurize Your Tank

Please follow the steps below to re-pressurize your tank on your RO system:


  • Turn off the feed water supply to the RO.
  • Drain the old tank completely thru the spigot. Read more

How To: Auto-Shut-Off (ASO) Valve Replacement

To replace the Auto-Shut-Off valve on your RO system, please follow steps below:

  1. Turn off the feed water to the RO system. Close the tank’s ball valve. Turn on the RO spigot, lift lever up & lock –> this relieves the pressure in the RO system, making line removal easier.
  2. The ASO valve is mounted on the RO frame. There are 4 ports on the ASO valve, see diagram below. Each port connects to a water line: Two RED lines in ports #1 and #2 (at bottom), two CLEAR lines in ports #3 and #4 (on top).
  3. Take ASO valve out of its bracket.  Please note how the 4 lines are connected to the old ASO, so you can re-connect the lines to the correct ports on the new ASO valve. Read more

How to Add UV-Light to RO System: at Stage-0

The UV light is best installed as the very 1st stage on your RO system, preceding the stage-1 sediment filter. To install the UV light at stage-0, connect the UV to your RO system as follows:

See Diagram:   Diagram shows how RO should look after UV light is added at Stage-0.

The UV light has 2 ports: The Feed water port is covered with a Red cap. The Output port has clear tubing with plastic compression nut.

Feed water: Remove the RED feed water line from Stage-1 pre-filter at point A. Read more

Chrome Feed Water Adapter is Too Big to Install

The APEC RO unit comes standard with a 1/2″ Chrome Feed Water Adapter. Most under-sink pipe size is 1/2″, but some may be a special 3/8” size. If the supplied 1/2″ feed water adapter is too big, you may need to use a 3/8″ feed water adapter.

If you are not able to find this component at your local hardware store, please contact an APEC Representative to obtain the 3/8″ feed water adapter.

If the issue was not addressed, please contact us at:
800-880-4808, or

Black Carbon Fines or Particles in Pure Water

When the Reverse Osmosis System is first installed, you must flush out the first tank of water. The Stage-5 Carbon filter is a GAC (granular activated carbon) filter so it contains loose carbon media. When water runs through a new carbon filter, it is common for the filter to release a small amount of loose black carbon fines.

If you still experience black carbon fines or particles after the first tank flush, please follow the steps below.

  • Turn off the feed water to the RO unit.
  • Open the Pure water faucet and let the water run till it stops. Read more

How to Replace UV Light Bulb

Please replace the UV light bulb after 1 year of service. After 12 months, the light bulb loses its strength. Pro-long use after 1 year will not obtain optimum results.

UV light bulb changing instructions:

  1. Unplug the light Transformer from the power outlet.
  2. Do not open the UV light housing. Read more

How Full Can My Tank Fill Up?

Your incoming water pressure and temperature will determine how full and how fast the storage tank will be filled. The stronger your input water pressure, the faster and fuller the tank can fill. If water pressure is low, the tank will fill slower and it will not fill up to its full capacity.

For a non-pumped RO system:

The 4* gallon tank will fill up according to your input water pressure as follows:
Input 70+ psi —> tank fills 3.1 gallon (almost 100% full)
Input 60 psi —> tank fills 2.8 gallon (about 88% full) Read more

Adding A Specialty Filter Housing to Your RO system (Before RO):

  1. Turn off Cold water supply to stop the feed water to RO system.
  2. Disconnect the RED line at point A (see enclosed diagram) where feed water goes into the 1st housing.
  3. Cut about 1 inch off the end of this RED line to get a new & even end, then connect this end to the new extra filter housing’s “IN” port – simply push the line into the quick-connect fitting. Do not add any inserts to the line, it’s not needed. Read more

Adding A Specialty Filter Housing to Your RO System (After RO)

This specialty filter stage should be connected as the last stage – between stage-5 and the pure water-dispensing faucet.

  1. Turn off the tank ball valve (point Y).
  2. Cut the clear tubing which goes from the stage-5 filter (small horizontal inline post carbon filter) to the RO faucet.
  3. Insert in the clear tubing coming from the stage-5 filter to the “IN” port on the specialty filters housing. (Just push tubing into this quick connect connection. No nuts or inserts are needed) Read more

DI Cartridge Replacement Schedule

The De-Ionization (DI) filter cartridge is made of a mixed bed DI resins. The resin bed has the capacity of treating approximately 7,695 ppm of Total Dissolved Solids (TDS). Therefore, the number of gallons each DI cartridge can treat depends entirely on the TDS level of your input water going into the cartridge.

To calculate how many gallons the cartridge can last given your TDS level, please use the following formula:

  • Measure the TDS level of the water before it enters the DI cartridge. Call this variable “X”. Read more

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