Maintain Your Spotless Deionized Water System (Resin)

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The quality of spotless car wash depends on the deionized water that your system is delivering.

Maintaining the deionized water system, which might be set up in the back of your garage, requires periodic maintenance. Don’t panic. This includes mostly changing the resin cartridges or refilling the resin cartridges.

Deionized water system performance depends on the effectiveness of the resin cartridges. Resin cartridges absorb the hardness of water or particles from the water.

Depending on the quality of water (TDS in ppm), resin lifespan shall vary.

How Many Times Can I Wash My Car Without Changing Filters?

I own a CR Spotless DIC-20. The deionized system will treat water depending upon inbound water quality. This is where the term TDS in ppm (parts per million) comes.

The relation between TDS and Gallons of water treated is inversely proportional. The lesser the TDS of inbound water the higher is the treated water.

It is expected that with 2 GPM flow of water and a TDS of 200, approximately 200 gallons of water can be treated before you have to change the resin cartridges or refill the resin. So, you can expect to wash your car 15 times if you use 10 gallons of water per wash.

Here’s a typical chart to understand the Gallons of water treated vs TDS:

TDS Count (PPM)Gallons Treated
Ref: Using 2GPM flow and CR Spotless DIC-20

As you can see, deionized water is so efficient in a low TDS water profile. Let’s dive into more water consumption details.

Let’s assume:

We are using a pressure washer with a 1.2 GPM water flow set up with the deionized water system.

Inbound water TDS in 200 ppm

We are washing the car(only final rinsing) for 5 minutes

Hence, the water required for this wash is 5*1.2 = 6 Gallons

From the above chart, we can see 388 Gallons of water can be treated in this TDS range. So, I can have approximately 388/6 = 64 washes!! Insane!

This might sound way too much but this is a calculation based on the time of wash and pressure washer GPM. The wash count will drastically reduce if you use a high GPM pressure washer or wash the car for more time.

Tip: Never use deionized water for the whole wash. Use it only for final rinsing.

When Do I Need to Change the Resin?

If your system has a TDS meter, you must change resin within 15-20 ppm reading.

The final delivery TDS might always read 0 ppm. However, high ppm indicates less efficient resin. Usually, no water spot is observed within the 10 ppm range. So, you need to pay attention to the TDS reading and do the maintenance in time.

On top of that, the shelf life of a typical resin cartridge is 12 months. My CR spotless usually last for 18 months depending on the TDS vs GPM relation shown above.

How to Change Deionizer Resin Cartridges?

This is fairly easy if you are using cartridge-type resin in the resin housing.

Step 1: Stop the operation and simply close the water supply into the resin unit

Step 2: Unplug the hose connection

Step 3: Simply unscrew the resin cartridge housing and remove the resin cartridges

Step 4: Dispose of the resin and refill the cartridges with new resin

In case if you have those big cylindrical resin chambers, you need to empty those and refill them with new resin.

Regeneration of resin is excellent practice for the environment. However, this is a long and hazardous process that requires expert help.

Resin Refill Alternatives

Resin refill can be costly if you are a heavy user of the home deionized system. Firstly, I would suggest getting a large resin cylinder if you are a professional in this area.

For an average home user, most of the deionizers are cartridge resin type. As you have read above, on average 30 washes are achievable.

If you want to get more out of your resin you need to modify the cartridge/holder.

Let’s follow these pictures:

Simply unscrew the resin cartridge housing and remove the cartridge. We are not going to use it anymore.

You need to buy resin in bulk for this step. Now, fill up the housing fully with resin. Simply, put a pipe with an outer diameter slightly less than the upper part of the housing.

Now just push the pipe upward and tighten the housing firmly.

You now have more resin for longer use.

Deionized Resin Change or Refill Cost (TOTAL)


  1. TDS = 200
  2. Pressure washer or Nozzle GPM = 2
  3. Car rinsing time = 10 min
  4. Washing car in every 2 Weeks
  5. Depending on TDS, resin treats 388 Gallons of water

Now, each wash requires 20 gallons of water. So, every two weeks we need 20 gallons of water to be treated with resin cartridges.

This means in around 388/20 = 19*2 = 38 weeks we need to change the resin cartridges depending on the above conditions.

CR Spotless Replacement Cartridges For DIC-20 cost approximately $160. Check the latest price on Amazon.

So, we need to change the resin cartridges once a year that would cost $160 (Approximately). Which is worth the money once a year in exchange for a super spotless car wash. However, you can buy in bulk. Check this 1 cubic foot pack on Amazon which can refill DIC-20 cr spotless 3 times.

On the other hand, if you have a tank-type portable mixed bed deionizer, you can expect to get the same amount of treatment and would need to refill resin around the same time if it was a cartridge type.

Check this Spotless Portable Mixed Bed Deionizer on Amazon

The advantage of tank-type resin is in the bulk price of resin which is almost half the price of cartridge fillings.

Disclaimer: This pricing may vary in time and of course depend on water or other conditions. This is an estimate only.

Can You Use CR Spotless With Pressure Washer?

Not only with this specific brand, but you can also in fact use a pressure washer with any deionizer.

All deionizer for car washing come with special fittings or connectors which can easily accommodate a pressure washer.

Using a pressure washer can reduce resin use dramatically. In some cases, this could be as much as 75% less resin occupancy. Most electrical pressure washers are in the range of 1.2-1.8 GPM which is less than the typical nozzle in terms of water flow. On top of that, pressure washer nozzles spray water in high force instead of flowing high water like a normal nozzle. This reduces water consumption AKA resin uses.

However, it is recommended to only final rinse your car with a pressure washer and deionizer combo. Also, remember to run a dew spray using raw water after you are finished using deionized water. This will save your pressure washer pump.

Final Words

In a nutshell, this was an overall idea of the maintenance interval and related cost of resin refills depending on various conditions.

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