Mix Bed Resin filter

DI filter, DeIonisation, mixed bed resin, filterhousings

The video shows filterhousings for refill of mixed bed resin and a
filter in action making pure water close to 0ppm or 0µS. YouTube

The player

New mixed bed resin for the production of ultrapure water or de-ionized water.

Some uses the resin without a reverse osmosis unit to make 0ppm water, but it is expensive. In a reverse osmosis system the DI-filter MUST be placed after the membrane, which typically makes water with 20-50µS (10-25ppm). Thus, the water is already well filtered before it comes to the DI filter, and thus the resin last longer.

Refill

The filter housing can be refill and I sell 2 different housings:

A) An inline 0,25L housing to be refilled with 170gram.

B) a cartridge to be inserted in a 10" filter housing. The cartridge can be refilled with approx. 400 gram. The advantage with this one compared to the small 0.25 filter is that the filter housing stands upright, and the water always flows properly from below and upwards.

Til shoppen

You can put both A and B at any system AFTER the membrane, but most people with a small 3-stages system prefer the small 0,25 liter inline filter A). If you have a system with large filter housings, you might prefer the cartridges B). See below under Capacity

If you have a system with 3 large filter housings linked with tubes, you might want to use the third housing as resin filter and in this way you avoid buying another filter housing. I have described it here. Remember that the resin filter must come AFTER the membrane. With some (cheaper) RO systems, the filter housings are built together and NOT connected with tubes and with these system you cannot do it.

How to fill the containers

I've read in a german forum from an expert. How important it is, I do not know, but it does not hurt to do it this way: No small grains must move. If there is too much play in the filter container, the individual parts of the ions connect to each other. Fill the resin slowly in small portions in the container, then fill enough water slowly until the water is just above the resin.

Slightly rotate and swing your container so air bubbles can disappear. Continue this way until the container is full.

The water must be forced to meet so many resin balls as possible with as much contact as possible. If the resin is not packed very well, the water might find its own way without encountering too many resin beads.

Capacity

Published several places and my preliminary studies show: The greater the volume of resin and the slower the water runs through the resin filter, the cleaner the water. And from an experienced german person I have been told:

After an osmosis system 1 liter resin purifies 800-1200 liters of water by 30-40µS to 0-1µS at a flow rate of approx. 10 liters per hour.

Some window cleaners are satisfied with 3-4ppm (6-8µS) and change the resin at this level. Aquarists have different requirements, some changes at 1ppm

The picture right shows Mercury equipped with a 125GPD membrane with the small 0.25 L resin filter. It's all about the contacting surface and time. Therefore, the water should run as much upward as possible in order to maximize contact.

Test of efficiency

Until now I've only seen the studies on the performance of resin after an osmosis at Waterpilot.com. The graph at right shows a 10" filter with a cartridge, see above at B)

I myself started to test. I started with a 3-stage system with a 125GPD membrane and the small 0.25 Liters resin filter. I use TDS-3, EC-3 and uses AP-1 and AP-2 as control meters - until now they have measured the same.

and I have stopped the test, because it continues probably for many more liters. A Dane writes in a forum that he has made over 2,000 liters of water with only 2µS with 0.6 liters of resin, so I could probably go on for 1,000 liters at 5µS, but it is a waste of water.

Saturn with 3 resin filters

A window cleaner says that Saturn, producing over 1,000 liters a day (a high flowrate), and three 10" filter housings with cartridge have made 15,000 liters of water with 000ppm after the second filter. After the first filter housing he gets 002-003ppm. The resin in first DI filter is mostly used, the other ones less. He moves the filter housings around to use them all the same and replaces the resin when the value is no longer acceptable.

RO system with flow 30 liters/hour

I've tested a system with a flow rate of 30 liters/hour. Here is the flow rate so high that it has an impact. With a 0.6 liter DI filter I make 1.6 µS and with 2 DI filters I make 0.8 µS. Here volume and flow rate has an impact.

Important: In a RO system: The DI filter MUST come after the membrane.

How to store the resin

Keep the resin so humid and dark as possible in airtight plastic bags. When I receive a bag of 25L, I open it and fill half a kilo in a plastic bag, tie a knot and put it into a big black plastic bag. Finally I have approx. 36 half-kilogram in airtight plastic bags in the dark.