Cleaning Hard Water Scale From Reverse Osmosis Membranes

The powder coating industry and the metals finishing industry has found Reverse Osmosis to be beneficial to provide clean water to clean and rinse parts. Using Reverse Osmosis metal finishing industries have reduced water consumption and overall wastewater from high conductivity discharge. Some additional benefits include:

  • Spot Free or Low TDS (Total Dissolved Solids) water for final rinse. Some times in high-quality applications Reverse Osmosis may be followed up with De-ionized (DI) Water providing ultra high purity.
  • Reduction in scale and sludge formation on / in heat exchangers. Calcium and magnesium will precipitate out on heating surfaces over 105 Degrees F.
  • Low TDS (Total Dissolved Solids) allows for reduction in chemical usage and dumping due to high conductivity. This reduces waste, water, heating energy and chemicals which provides an overall savings.

Reverse Osmosis systems in Metal Finishing is an important piece of equipment, so when our customers call and say they are down, we respond. Complete Water Solutions was called out due to low flow and high conductivity. The customer was running out of RO water needed for the Parts Washing Booth and thus forcing to slow production down or shut down all together.

Complete Water Solutions came out same day and began to investigate.  We started at softeners. The softener system composed of a two tank unit. Fleck 2900 with 7 cubic feet of resin in each tank.

fleck 2900 softener tanks, complete water solutions, industrial water treatment service

We first start by noting which unit(s) are on line and how many gallons are remaining. Unit #1 was on line with 5,687 gallons remaining and unit #2 in regen. The next step is to test the water both from the inlet and outlet of the softener. Inlet hardness was 26 Grains Per Gallon (444.6 PPM) and the outlet was 16 Grains Per Gallon (273.6 PPM)

The next step we do is to review the programming logging the current settings. Performing this on every service call provides a history of the last program. This is good for a few reasons, one it provides a written back up should the program be lost. If the controller needs to be replaced the program can be re-installed quickly without having to search far. Lastly some times programs get changed, mostly by accident.

Current Program Settings

system 7 program
valve address 1
2 valves
meter immediate
valve 2900
down flow
remote off
5% capacity safety
30 gpg hard
backwash 10
brine rinse 60
rapid 10
brine fill 20
2.0 paddle

Next we waited for unit #2 to finish regeneration. During the refill process we noted that the brine tank only refilled 8″ of water. 8″ of water for brine is not enough. Before we begin to dig into the refill limitation we took down total flow processed by both softener vessels (this data is not available to get during regeneration)

To begin to understand the limited refill we begin to look at both the brine valve and the refill valve.

We cleaned the brine valve, brine piston, and the injector assembly

cleaning brine valve, cleaning brine piston, complete water solutions cleaned brine valve, cleaned brine piston, complete water solutions

Regenerated Brine Tank

After cleaning these items we were able to successfully refill the brine tank to the correct levels. This also improved the brine draw rates allowing good brine saturation.

After the repairs we regenerated unit #1 again (after allowing some time) After the regeneration the softener tested at 0 GPG = Soft water

This hard water is what caused the RO System to have reduction in flow, increased pressure and increased conductivity. Before cleaning the Reverse Osmosis System we took down pre-data so we have a starting point. We also take data after cleaning to confirm the success of the cleaning along with having operational data should we need to look back.

ro pre cleaning

ro housing #1. 22 microsiemens
ro housing #2. 18 microsiemens
ro housing #3 180 microsiemens

This RO System did not have CIP Connections (Clean In Place) to allow for onsite cleaning. We installed those while on site. The CIP Connections allow you to recirculate the chemicals that are needed for cleaning. We have a drawing that shows you an example of the layout – Cleaning Connection Example

clean in place system, complete water solutions, reverse osmosis system service

Complete Water performed the cleaning use Avista Membrane Cleaning Products. We use the Avista products as they have been certified NSF approved for off-line cleaning. Because the membranes were scaled we only performed a cleaning using Low pH Cleaner

Avista P303 Low pH Cleaner – Data Sheet

cleaning scaled ro membranes, ro scale removal, complete water solutions

Removal Of Scale Turned Cleaning Solution Darker

reverse osmosis controller, post ro cleaning results, complete water solutions




















After the first cleaning flows were up to 8 GPM. Past data shows flow at 10 – 12 GPM. So we performed a 2nd cleaning.

After cleaning the second time 11.4 GPM permeate and 3.9 GPM concentrate.
ro housing #1. 6 microsiemens
ro housing #2. 10 microsiemens
ro housing #3 20 microsiemens

After the 2nd cleaning, we successfully recovered back the flows, pressures and conductivity.

Do you need your RO System Cleaned or Repaired?

Don’t Wait Contact Complete Water Solutions

(855) 787-4200   or email


This RO Membrane Cleaning Service Took Place In Indiana

About The Author

Nathan Olszak
28 Year Of Water Treatment Equipment Experience. I have been blessed with the opportunity to learn from the ground up. Starting in the water treatment field as a service technician. Servicing all major brands of water treatment equipment. Give Us A Call (855) 787-4200 or Email

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