Do I Need to Rinse My Carbon Filters Separate from the RO Membrane to Avoid Fouling from Carbon Fines?

Most reverse osmosis systems have a similar layout of sediment and carbon pre-filters, the RO membrane, and then a post carbon filter. It is also advised that you do not use the first 2 to 3 tanks of water from your RO system after initial installation and filter replacement to adequately rinse the system, filters, and RO membrane. But should you also be rinsing your carbon filter separately from your RO Membrane?

In short, yes. Many manufacturers will skip this step to avoid overwhelming their customers with yet more information for the setup and maintenance of their RO system. However, rinsing your carbon filters of carbon fines before allowing the water to flow to the RO membrane can help prolong the life of the membrane by preventing premature fouling due to the carbon fines.

Carbon filters perform a very important function in your RO system, and are actually needed to protect your RO membrane from damaging chlorine. However, if you have ever installed a new refrigerator filter you have seen that at first the water that flows through the filter appears black and cloudy. This is caused by a buildup of excess carbon fines running off the filter media. The fines are harmless, but it is still best to rinse a carbon cartridge before your first use. RO membranes have very small pores in order to trap the smallest of particles, and they can foul very quickly. So it stands to reason that the initial carbon fines from your pre-filters can cause fouling of the membrane if not rinsed first.

The following instructions are specifically catered to the SpiroPure SP-RO100 Reverse Osmosis System and its tubing and cartridges. However, the instructions can be used for any RO system, just be mindful that the color of your tubing and cartridge types may differ. To rinse your pre-filters while bypassing the RO membrane, use the following steps.

If you are installing your system for the first time:

1. Make sure that both the cold water supply valve and feed water adapter valve are shut off.
2. Unscrew the filter housings.
3. Take out and unwrap the pre-filter cartridges.
4. Reinsert the unwrapped cartridges into the proper housings in the order of Stage 1: SP-AP110 Sediment Filter, Stage 2: SP-GAC-10R GAC Filter, and Stage 3: SP-CBC-10 Solid Block Carbon Filter.
5. Make sure the O-rings are properly seated in the housing.
6. Screw the housings back onto the manifold clockwise.
7. Tighten the housings with the included housing wrench, making sure to tighten without over-tightening to avoid damaging the O-rings.
8. Insert the 1/4" white tubing from the feed water adapter into the system inlet fitting by the stage 1 (sediment) filter cartridge.
9. Insert the 3/8" red tubing from the drain saddle to the outlet port fitting on the manifold by the stage 3 (Solid Block PAC Carbon) filter cartridge.
10. Turn on the cold water supply valve and slowly turn on the feed water adapter valve.
11. Let the water fill the pre-filter housings and flush the cartridges for at least 5 minutes.
12. Shut off the feed water adapter valve and cold water supply valve.
13. Disconnect the 3/8" red tubing from the outlet port fitting of the manifold.
14. Connect the 3/8" red tubing to the wastewater port by the RO membrane.
15. Connect the tubing from the RO membrane housing to the system outlet port fitting.
16. Continue following the rest of the installation instructions as presented in the system manual.

If you are replacing your filter cartridges:

1. Turn off the feed water supply valve and the cold water supply valve.
2. Unscrew the filter housings.
3. Remove and discard the old filter cartridges.
4. Install the new filter cartridges, making sure to install them in the proper order of Stage 1: SP-AP110 Sediment Filter, Stage 2: SP-GAC-10R GAC Filter, and Stage 3: SP-CBC-10 Solid Block Carbon Filter.
5. Make sure the O-rings are properly seated in the housing.
6. Screw the housings back onto the manifold clockwise.
7. Tighten the housings with the included housing wrench, making sure to tighten without over-tightening to avoid damaging the O-rings.
8. Disconnect the tubing that runs from the RO membrane housing from the system outlet port fitting on the manifold by the stage 3 (Solid Block PAC Carbon) filter housing.
9. Disconnect the 3/8" red tubing from the wastewater port by the RO membrane.
10. Connect the 3/8" red tubing to the outlet port fitting on the manifold.
11. Turn on the cold water supply valve and slowly turn on the feed water adapter valve.
12. Let the water fill the pre-filter housings and flush the cartridges for at least 5 minutes.
13. Shut off the feed water adapter valve and cold water supply valve.
14. Disconnect the 3/8" red tubing from the system outlet port fitting.
15. Reconnect the 3/8" red tubing to the wastewater port by the RO membrane.
16. Reconnect the tubing from the RO membrane housing back to the system outlet port fitting.
17. Turn on the cold water supply valve and feedwater supply valve.

While it may seem like a hassle to perform the extra steps of rinsing your pre-filters separate from your RO membrane, in the long run it can assist in helping extend the life of your membrane as you protect it from premature fouling from carbon fine buildup.