Backwashing a RO/DI Unit

[zamboniMan]

How do you backwash them?

[jeff@zina.com]

Read the directions that came with the unit. :)

It's not really "backwashing" but most RO membranes need cleaning and DI cartridges need replacing. Some systems do this automatically, on others you just replace the cartridges according to the diagnostics. It really depends on the unit as to what maintenance you need to perform.

Jeff

[zamboniMan]

If I had directions I would have read them :-p

[jeff@zina.com]

Most docs are available online. If you tell us what unit you have then maybe someone here has a similar unit.

Jeff

[aalbina]

How do you backwash them?

You just flush water past the membrane. Check out http://www.simplydiscus.com/library/water_chemistry/ro_di_filtration/ro_parts9.shtml. You basically bypass the flow restrictor on the waste water output which pushes water at a much faster rate past the mebrane effectively (or not) flushing contaminant build up down the drain.

Adam

[diveshooter]

How To Sanitize A Reverse Osmosis (RO) or Reverse
Osmosis/Deionization (RO/DI) Water Filter
Chlorine is an excellent oxidative agent that can be used to sanitize and disinfect a RO or
RO/DI filter. If you believe you need to sanitize your filter unit follow the steps below:
1. Remove all filters including the RO membrane. If you have a “Taste & Odor”
polisher that needs to be removed too. IMPORTANT: You must remove the
RO membrane from the membrane housing before proceeding or you will
destroy the membrane.
2. Replace all EMPTY canisters except the 1st one.
3. Put 1/2 cup of household bleach in first filter housing and install it on the filter
unit.
4. Turn the source water on, slowly pinching the drain line to force water to exit the
membrane housing from both ports.
5. Wait to smell bleach from the drain and product side. If you have a drinking
water system you need to smell bleach from the faucet too. You can use a
chlorine test kit or your nose to test for the presence of chlorine. As long as there
is some bleach in all parts of the system you will be disinfecting it.
6. Once you have bleach to all ports, shut the water off and wait 20 minutes.
7. Check to make sure there is still bleach to all ports. If you smell the bleach then
you have successfully disinfected you filter system. If there is no bleach smell
left after 20 minutes it means there was still undesirable material in the filter,
which was not fully oxidized and you have not killed everything. In that case,
repeat the above steps until you can smell chlorine at the ports.
8. Now flush the system with fresh (no chlorine) water for 10 minutes. Make sure
water is flushed from both ports on the exit side of the membrane housing.
9. Test for bleach from all ports. If there is no bleach smell or chlorine left after
flushing you can reinstall your filters. If there is still bleach present, continue to
flush until all the bleach is all gone. IMPORTANT: You must be sure and
flush all bleach from the system before you replace the membrane in the
membrane housing or you will destroy it with the residual chlorine.
This is an excellent time to replace your filter cartridges to avoid any system
contamination. After reinstalling your cartridges, your filter will be as good as new.
Copied from the AQUAFX website.

[marineworld]

Zamboniman,

Backwashing an RO/DI unit is simple if you have the proper valving. Your simply reversing the flow of water across the RO membrane to blow the contaminates out to the drain. This action flushes the outer surface of the membrane clean and greatly extends the life of that membrane.

Flush kits are available from several online aquatic suppliers. This is an action that one should do every couple weeks or more often, depending on the amount of water you go through. Generally 2-3 minutes of backflushing each week should be good.

Good luck,

Marineworld