Dual tanks or single for water-fed window cleaning with mixed-bed resin

Would using two mix-bed resin tanks in areas of high TDS conserve resin by using this technique: Once the first tank goes south move tank #2 into position one and put a new tank into #2 position. It is explained here: http://www.windowcleaningworld.com/shop/index.php?route=product/product&product_id=712
Wouldn’t it depend if the Cation resin component that removes most of the spotting has had it or not, even though the Anion component may be still working? If that was the case then you would be running water through an old tank of resin for no reason.
How could this be effectively tested exactly? What would the PH reading be for example?

An RO is going to do a much better job of conserving resin and way more cost effective. Once the resin goes bad you’re going to have to change it anyway so why not just have a bigger DI tank so It last twice as long as two small tanks, maybe longer?

Thanks. Agreed - but my guys purchase their own equipment and use DI tanks. Was just wondering if the mixed-bed twin tank ‘Theory’ could be proven to conserve resin or not.

The duel tank system was part of the old system when you purchased Caton and anon in separate tanks. This made it much easier for the distributor to recharge the tanks. With mix bed Resin the Resin has to be separated then recharged. The advantage of the mixed bed is you get more of a scrubbing action with the water The need for a two tank system no longer exist because of the mixed bed. It also frees up space in your vehicle versus a two tank system Also once a tank has expired it will start to release minerals back into the water. I have seen expired DI make the TDS higher than the TDS coming from the water source

yes this happened to me.

with mixed resin and 2 tanks the second tank is your assurance because di can fail suddenly and you have no awareness.

Thanks guys! Much appreciated.

So John you’re saying twin tanks are a thing of the past and Cactus27 you are saying you still use twin tanks?

Yes with mixed bed resin there is no need for 2 tanks. The two products are mixed together in one tank. There are still those that connect two mixed bed resin tanks in conjuction especially if in a high TDS area and have 1/2 cubic tanks. My point was if the first tank expires it will release minerals into the second tank causing it to expire at a higher rate.
It’s a personal choice


john has a much broader base of experience than i.

i use ro/di. city water here is around 180 ppm and the cost of resin is prohibitive.
i have had the di fail and increase the tds to higher than the ro was giving it. but this was only after my system had been trying to process water over 700 ppm and then returned to regular city water.
i have worked with a friend who has a single di. we checked the tds at start of job (college building about 60 feet high). he was doing tops i did bottoms.
end of the day i asked him how his resin was holding up and he said he hadn’t checked. so i checked…his resin was completely shot and the water was 180 ppm same as the in put. he had no idea when it failed thru the day.
a second tank in line would have still given him pure water.
it takes quite a while for resin to become so contaminated it raises the tds.
either you need to check tds regularly but with a single tank you may end up with bad quality or having to redo stuff you cannot even tell if it really needs redoing.
as john says there is no need for 2 tanks with mixed resin but i would not be comfortable with what i would consider an unreliable system.

Thanks guys - I really appreciate the clarification.

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Forgive the ignorance here, but this raises an additional question for me.

I recently watched a YouTube video in which an older gentleman was using a two tank DI system. He replaced his resin 1 tank at a time, ran the water in one direction until his fresh resin tank tds began to rise; he would then replace the oldest tank and change the direction. The idea being that even failing resin, to a point, will reduce the tds over just strait tap tds. The older tank cuts the tds and the new resin in the other tank is put under less load and lasts longer. When the tds goes up, you switch the flow and resin in the old tank continuing the process.

My question: Is this a viable technique?


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Yes, definitely a viable way to increase the life of your resin.

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I ran a dual tank for quit sometime. Till I went with pump an 50 gallon tank.
Dual tank is a good way to go it just let’s you get the most out of your tank as Mathew says.
Try ine tank for a while an see how much time you get. Then try the dual tank. I guess that’s the only way to see if dual is worthy. Always good to have 2 anyway.

Absolutely viable and worth it if you can have the resources, room, and attention to tds creep that it takes to profit from a dual DI rotation system.

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a gallon meter will let you know when your tank is usually going to expire

based on the tds in your area you can figure how many gallons youll get out of tank

WCR has a chart somewhere and the whoever you get your tanks from can tell you as well