What is PPM and TDS?

TDS- stands for total dissolved solids. This is the accumulation of minerals measured in Parts Per Million or PPM in your tap water. In NZ our typical water quality ranges from 50- 80 PPM. Below is a picture of the meter that takes the reading of the water quality and is sold with every WWWCS system.



What is Deionized water?

We get a lot of questions about resin for water fed pole cleaning: when to change it, how to change it, how long it lasts, how much it costs, and what sort to use. There are a lot of misunderstood conclusions and context about ion exchange resin on the internet for water fed pole window cleaning, so in this post we’ll try to give you a bit of clarity.

The de-ionisation system is such a simple to use and easy to manage water purification system, providing for maximum cleaned windows. There are only a few things required in terms of maintenance of it, and one of which is the changing of resin when it expires.

Window cleaning mixed bed resin is the lifeblood for water fed window cleaning. It works to purify your water (removing dissolved solids / minerals) to give a spot-free finish. The better quality and specific use the resin, the longer it’ll last over a wide range of water qualities.

The one benefit purified water has over tap water in cleaning glass is to stop spotting when it dries. Purified water has effectively no greater cleaning power than tap water. Purified water has effectively no greater cleaning power than tap water.

What is mixed bed (MB) ion exchange resin?

Resin can be described as looking like wet sand. In reality it is made of chemically treated crosslinked polystyrene beads, with very large surface area ratio for their size. Mixed bed resin is made up of anion and cation removing resins. These are positively and negatively electrically-charged resin beads  which work to exchange anion and cation particles from the water supply for hydrogen (+) and hydroxide (-) ions which form H20.

Mixed bed resin for water fed pole cleaning.

MB resin is used in a wide variety of industries, each having specific performance requirements. Window cleaning only requires resin to stop water from spotting when dry. Not all ions in normal water supplies will cause spotting (especially on the anion side of the equation). Spotting will occur if cations are not removed. So your mixed bed resin will need a sufficient ratio of cation resin. Combined with a serviceable carbon pre-filter we can maximize the number of spot-free litres of water produced.

Manufacturers make many different types of MB resins with variable ratios of cation to anion, different exchange capacities and conversion ratios.

Thermax Tulsion MB115 is the window cleaning industry standard for performance and price, providing reliable performance over a broad range of water conditions. For areas of hard water TDS (greater than 150ppm (parts per million)) we are able to offer Thermax Tulsion MBHW, providing 10–15% more spot-free water than MB115. MB115 and MBHW work best at a TDS of below 350ppm. We do not recommend regularly using these resins for water with a TDS above 450 with high alkalinity (e.g. bore water). If working in these areas, consider an RO (reverse osmosis) system as a pre-filter.

How long will it last?

Provided you’re using a premium resin and a carbon / sediment pre-filter, the length of time your resin will last will depend on a number of factors:

  • How hard or soft the water is you’re running through your DI system. For example, resin will last far longer in Melbourne (TDS of ~30 ppm (parts per million) out of the tap) than it will in Perth (TDS of >200ppm out of the tap).

  • How many operators running from your system. The WWWCS DI systems allow for 2 operators running pure water at once, which will be double the flow of one operator and mean your resin is working twice as hard.

  • The amount of flow. A typical 2-jet brush will use approximately 100–150 litres per hour (1.8–3 litres per minute).You don’t need to use your DI system like a pressure washer, it only needs to form a curtain flow below the brush when rinsing. As a rough guide, a pressure of 40psi is adequate for 1–2 storey jobs, and 10psi for every level above that.

  • The size of your DI tank. The bigger the tank, the more resin, and the longer it’ll last. We recommend a minimum size 12.5L tank for most professional window cleaners. If you work in a hard water area you may look at using a 16L / 25L tank so that you change your resin less frequently.

With all these things considered, using Thermax Tulsion resin*, with a 12.5L tank at a regular flow for 1–2 storey work, will give you approximately 80–110  hours’ life to the resin in Melbourne, approximately 40–60 hours’ life to the resin in Sydney and Gold / Sunshine Coast and 10–20 hours’ life to the resin in Brisbane, Adelaide and Perth**.

  • * Figures are based on using Thermax Tulsion resin as it is the window cleaning resin. Other resins may have substantially less life expectancy.

  • ** Figures are based on using Thermax Tulsion HW (Hard Water) blend resin in SA and WA. Regular mixed bed resin will last 10–15% less in those states than hard water resin.

There are ways of extending the time between resin changes:

  • Pre-wash through a filtered water only outlet (bypasses DI resin) then rinse off with DI water.

  • Use Wash and Rinse detergent – it will clean and rinse glass faster, saving time and resin, especially on regularly cleaned windows. It will keep glass cleaner for longer, effectively reducing dirt adhesion to glass, speeding up cleaning next time.

  • Use tank rain water where possible, as it will have a very low TDS.

  • Reduce flow through brush. You need just enough flow for rinsing without having to slow brush movement.


When to change your resin?

Use a TDS meter to keep an eye on the outlet TDS every now and then. You’ll know your resin has expired when you’re no longer getting a spot-free finish on the glass. In terms of TDS, you’ll notice spotting above 10ppm, and should change it then.

For those who want to delve a bit deeper and maximize spot-free water from resin, you can monitor your outlet water’s pH levels to test for acidity (cation resin is operating if the PH is below your inlet supply water). Your resin will have reached its exchange capacity when it matches approximately half your inlet TDS.*

*If you’re not using MB115, MBHW or alternative brand equivalent, you should replace your resin shortly after it reads TDS greater than 0, as it may have a reduced cation resin ratio which will affect a spot-free finish.

How to change your resin?

Unscrew the head assembly from your tank and remove the central riser, tip out the resin, fill it up to the very top (12.5L of resin for a 12.5L tank), tap the tank on the ground 3–4 times to settle the resin, ease your riser back through it and screw the head back on. Optionally you can fill tank with 3–4 litres of water before refilling with resin to assist with re-fitting the central riser to bottom of tank.


Which resin should I use? Hard Water Resin Vs Mixed Bed Resin?

Our distribution network is able to offer true Thermax Tulsion Hard Water Blend resin, which, when combined with a carbon pre-filter, gives those in hard water areas (WA, SA, rural) an extra 10–15% spot-free water. If you’re working in those areas (TDS >150), choose Thermax MBHW Blend. For those in regular water areas, MB115 has the ideal ratio of anion and cation.

Thermax Tulsion is the world’s most popular WFP window cleaning resin. It’s designed for window cleaning and has the highest quality cation and anion (mixed bed resin components).


Single Tank vs Dual Tank.

In the early days of portable DI systems, before mixed bed resin was readily available, systems consisted of 2 tanks – one for the cation resin and the other for the anion resin. Mixed bed resin is now readily available and relatively inexpensive compared to 5 years ago, so the old 2 tank system should be a thing of the past unless you wish to regenerate your resin. There is no added exchange capacity to resin when using a dual tank. The reason being, the first tank will totally purify the water (unless it is too small for the job it is meant for). It won’t share the load across the two tanks. Once the first tank’s anion or cation reaches its exchange capacity (mixed bed anion and cation resins never reach their exchange capacity at exactly same time, which can confuse some google experts), the second tank’s resin will do the work of the expired anion or cation resin in the first tank. So you’re basically carrying a spare tank of resin around with you (which is heavy, cumbersome and unnecessary). Save yourself the trouble of filling two tanks and have a spare bag of resin on hand in your van instead. In order to achieve the maximum exchange ratio from your anion and cation, the FRP tank and distributor system – which is standard with all WWWCS DI systems – is the most efficient portable tank at evenly distributing fluid due to pressure, coefficient of friction and temperature remaining consistent. It is also important your system has a working pressure capacity of at least 125 psi (0.85mpa) pressure. Often metropolitan water supplies have tap pressures between 80–100 psi. A pressure surge may blow your system if it cannot handle the pressure (unless you are have a fitted inline pressure reducer). An important difference between portable DI Systems and installed DI Systems is the resin beads in portable FRP tank DI Systems are constantly moving when transported, exposing the total surface area of each resin bead to water flowing through the resin, achieving almost 100% of designed exchange ratio. If you wish to check the condition of your resin as TDS starts to climb simply lay the FRP resin tank down and stand  up, then check the TDS.


How much does resin cost?

Wherever you work, even in the hardest water areas, resin is inexpensive for the value of the work done. Based on buying a single bag of resin (25L), running costs are approximately $1 per hour in Melbourne and up to $10 per hour in the most extreme hard water areas, with returns of $100–$200 per man/h. Resin prices work on a volume discount basis, so if you bought multiple bags the hourly cost will go down again. For a tool that cuts your window cleaning time in half, is safer than using ladders, and is more efficient, it’s a no-brainer.

To maximize the return on your resin investment make sure you use a carbon / sediment pre-filter to keep the gunk out of your resin.

RO or DI?

De-ionisation and reverse osmosis are the two commercially available methods of purifying water for a spot-free finish. They can be used individually or in combination.

There has been a change in the past 5 years from RO/DI Systems to mostly DI Systems as DI is the easiest and most cost-effective method of water fed cleaning the most windows in the shortest time. No power or pump is required, just plug in and play with an easily transportable, compact system designed for window cleaning (multiple outlets, detergent dispenser, etc.).

You’ll use a DI system for any and every job. Reverse osmosis is a great option if you’re using your DI system a lot on big jobs in hard water areas. While it’s an expensive capital outlay, and requires power, a pump, and flushing before and after every use, it’s ideal as a pre-filter for your DI system on long jobs.

The main reason for purchasing and RO system is to save money on replacing MB resin. If you are spending more than $50 per week for resin per DI system call us to see whether an RO system is right for you.


How does the system work?

As the water passes through our filter system, the minerals get stuck onto the pre filters and then the resin beads allowing only ultra purified water to pass through- spot free water!


How many litres of pure water does my machine make?

The answer depends on the inlet quality of your water. Using the chart below you will see that if your inlet TDS is 50, then your machine will make approximately 3200 Litres, Throughout NZ the typical TDS in your water is between 50-80 ppm in municipal areas.

resin yeild graph.PNG


Can i use a pressure washer with my pure water cleaning system system?

Yes! A domestic water blaster draws approximately 5 litres or less of pure water through the system. This is a great idea to rinse off the soap off your car quickly or to maintain your vehicles appearance on a frequent basis without the need to scrub or chamois. Using a water blaster will get the job done quicker! A water blaster can be used for cleaning windows but is not recommended.


How much inlet water pressure is ok?

Houses running off municipal water supplies will have a regulated water pressure that is safe for the Pure Water Cleaning System. Our pre- filter is rated at 90 psi and the resin tank is rated at 150 psi. Please make sure that you dont use your system if you are going to run over 80 psi as a precaution or install a reducer valve if a high pressure pump is being used.


The system is all hooked up but no water iscoming out, why?

You may have hooked up the system in reverse. Make sure that the inlet water is going to the pre-filter of your PW5L first. Also check for STOP ends on your hose. If you have further problems, please call PWS directly for advice.


What is Sediment Filtration?

Sediment filters are designed to remove suspended solids, which are also known as sediment, turbidity, or particulate. A sediment filter essentially functions like a net that catches unwanted dirt particles as your water flows through the system. Water can contain all sorts of sediment from rust to insects, dirt, algae and bits of washed in plant matter.

Sediment filters have a limited function. Only sediment that will become trapped in the bed of natural media is removed. Trace pathogen elements, heavy metals, and volatile organic compounds can still remain in the water.  Sediment filters are particularly beneficial when working in rural areas (well water) and are a cheaper alternative than the carbon filters for this purpose.


What are Carbon Filters?

Carbon filters remove sediment but they also remove chlorine, volatile organic compounds (VOCs), odors and unpleasant tastes from water. Carbon filters contain activated carbon, which is made through a special manufacturing process that creates more bonding sites. As water passes through a carbon filter, impurities like VOCs and heavy metals become chemically bonded to the carbon. As the water works its way through the filter, a lot of unwanted impurities will become stuck to the carbon bonding sites and the water will leave the filter much more pure than it came in.

Carbon filters are effective at removing the impurities that bond to carbon. Not all impurities do. Sodium, for example, is able to pass directly through carbon filters without being removed.