Replacing the DI resin in your tank is a 15 minute job on the driveway with nothing more than scissors: flush the spent resin out into the cloth bag using tap pressure, funnel in the fresh resin, and put the tank back together. When your TDS meter starts climbing off zero, this is all that stands between you and another run of spot free washes. Here is the full process, what comes in a replacement kit, and the small habits that make the swap clean and quick.
Watch the swap, start to finish
The video runs through the exact process on a real tank. The written steps below follow the same order, so you can watch once and keep this page open on the driveway.
When to replace your resin
The TDS meter makes this decision for you. Dip it in the tank's output stream before a wash:
- 0 to 5 ppm: the resin is working. Wash away.
- 6 to 10 ppm: the resin is on its way out. Order a kit and plan the swap.
- Above 10 ppm: replace it now. Water at this level can start leaving faint marks, especially on dark paint.
Do not wait until you see spots on the car. By then the resin is well and truly done and you have towelled a wash you did not need to. How quickly you get here depends entirely on your local water, and our resin life guide breaks down the expected output for every tank size and water hardness level in Australia.
What comes in a replacement kit
A Spot Free Rinse resin replacement kit is pre-measured for your tank size and includes everything the job needs:
- Fresh HFR mixed-bed resin in vacuum sealed 5 L bags, enough for your tank size.
- A black extraction head, filter only, with the rubber seal and no mesh, so you never have to flush through your own head.
- An extraction tube with no bottom basket, so nothing blocks the resin on its way up and out.
- A short extraction hose that runs from the OUT fitting into the bag.
- A filling funnel with a safety cap, so the beads go in the tank and not on the driveway.
- A cloth collection bag that catches the old resin. One bag holds about 10 L.
- Printed instructions.
Kits are matched to the tank range: $99 for the Mini, $159 for the Medium, $225 for the Large, and the XL kit at $349 as a special order. Once you own the kit, you only need the resin, so the Resin Only option is $69, $129 and $195 for the same three sizes.
How to replace DI resin, step by step
- Fill the tank with water. Run your hose into the IN fitting until water comes out of OUT. A full tank makes the internals easy to lift out.
- Open the head and lift the internals out. Push down and twist to unscrew the tank head. Lift out the head, the top basket, the centre riser tube and the bottom basket. If the centre tube stays behind, work it up gently while everything is still wet. Top the water up if the level has dropped.
- Fit the extraction head from the kit. Push the extraction tube straight into the bottom of the black head, twisting as you go to get it past the seal, then screw that head onto the tank. Rinse any beads off the threads first. This head has the rubber seal and no mesh, and the tube has no bottom basket, so the old resin has a clear run out. Set your own head aside while you flush.
- Set up the bag. Push the short extraction hose onto the OUT fitting, drop the other end into the cloth bag and pull the drawstring tight around it. Connect your garden hose to IN.
- Flush the old resin out. Turn the tap on full. The water pushes the old resin up the tube and out into the bag. A little water weeping from the OUT fitting is normal, there is no mesh in this head. Keep going until the water runs clear, then give it another minute. If the bag fills, turn the tap off and swap in the next one.
- Empty and refill. Unscrew the extraction head, pull the tube out of it and tip the water out of the tank. A few beads left in the bottom are fine. Put the riser tube and bottom basket back in. Run a strip of masking tape over the top of the centre tube before you pour: it is optional, but it guarantees no beads drop inside it. Sit the funnel on top with its safety cap over the tube, cut a resin bag open at the corner with scissors and pour slowly. If it clumps, shake or tap the tank to settle it. Lift the tank and tap the base down a few times to pack the bed, and fill to just below the bottom of the funnel. A small amount left over is normal.
- Put your own head back on and test. Wipe the threads clean, guide the riser tube through the top basket, twist your normal tank head back on until it clicks, check the rubber seal is seated and screw it down. Reconnect the hoses, run water through for 10 seconds, then dip your TDS meter in the output. It should read 0 ppm.
Why the kit comes with its own head. Tanks used to ship with a filter only head. Tanks sold in recent months come with the bypass head instead, and we do not want resin flushed through a bypass head because it can damage it. So every kit now includes the black extraction head to do the flush with. If your kit arrived without one, email us and we will send it. If you have the older filter only head and no black head, you can flush with that instead: unscrew the connector on the OUT side, lift the mesh trap out so the resin can get past, screw the connector back on, and put the mesh back before you refill. Never flush through a bypass head.
A few tips from doing this a lot
- Do it over grass or a bin. Escaped resin beads on a smooth driveway are slippery underfoot, so work somewhere spills do not matter.
- Keep fresh resin sealed until the moment you pour. The resin starts working on the moisture and air around it as soon as it is open, so do not open the bags the week before.
- Do not top up, replace. Mixing a scoop of fresh resin into a spent bed barely moves the reading. When the meter climbs, the whole bed swaps out.
- Hang the bag up to drain. Once the old resin has dried out, tip it into another bag and put it in the general waste. It is non-hazardous, the minerals it collected came out of your tap water. Never wash resin down a drain, and keep the cloth bag, you only need resin next time.
- Keep the beads out of your eyes. They sting. Rinse with water if you get one.
- Note the date. Write the swap date somewhere (a marker on the resin bag box works). Combined with your TDS readings it tells you exactly what your local water costs you per wash, and when to have the next kit on the shelf.
Why this matters more than it seems
A tank whose resin you replace yourself is the whole reason a DI system makes financial sense at home. Sealed cartridge systems make you pay for a housing every time the resin inside dies. With a media vessel you buy resin, not packaging, and the swap you just read takes a quarter of an hour. That is also why we would rather you replace resin confidently and often than stretch a dying bed: the resin is the consumable, the spot free finish is the product. If you are not sure which kit fits your tank, the sizes match the tank names, and if in doubt email us: admin@spotfreerinse.com.au.
Frequently asked questions
How do I know when my DI resin needs replacing?
Check the output with the TDS meter that came with your tank. At 0 to 5 ppm the resin is fine, above 10 ppm it is time to replace. Rising readings are gradual, so a quick check before each wash gives you plenty of warning.
How long does replacing DI resin take?
About 15 minutes. The head unscrews by hand, tap pressure flushes the spent resin out into the cloth bag, and the fresh resin pours in through the funnel. The only extras you need are scissors to open the resin bags, and a strip of masking tape to cover the centre tube while you pour.
Can I regenerate DI resin instead of replacing it?
Not at home. Regenerating mixed-bed resin requires strong acids and caustic soda, which is industrial water treatment territory. Replacement with a pre-measured kit is the safe and economical option.
How do I dispose of old DI resin?
In the general waste. Spent resin is non-hazardous, the minerals it holds came out of ordinary tap water.
Do I need to dry the tank before adding fresh resin?
No. Tip the water out and pour the fresh resin straight in. The bed works submerged, so a little water left in the bottom is not a problem.
Why does the kit come with its own head?
So you never have to flush through your own one. Tanks sold in recent months come with the bypass head, and pushing spent resin through a bypass head can damage it. The black head in the kit is filter only, with the rubber seal and no mesh, so paired with the supplied tube (no bottom basket) the old resin runs straight out. Your own head goes back on for the rinse.
