1 cube vs 2 half cubes?

Two half cubes should yield the same amount of pure water as one full cube, but if you run them together in series they will last even longer. My question is how much longer?

It makes sense that they would run longer in series. I’d like to know this as well.

I am interested in this as well.

Perhaps Perry will chime in. Is he asleep now. Haha

TWO–BED
The cation and anion exchangers are connected in series.
The cation tank removes positively charged ions (calcium, sodium,
magnesium, iron, manganese and potassium). The anion tank removes
negatively charged ions (sulfates, chlorides, carbonates, bicarbonates,
nitrates and silica). Strong base anion units typically produce 0.2
megohm water at a pH of 8-9, whereas weak base anion units produce
lower water quality, a pH of 6-7, and do not remove silica or CO2.

MULTIPLE–TANK SYSTEMS
Three tanks or more are connected in series; or parallel; or a
combination of the two.
Produces high purity water in any desired
quantity. Systems may consist of strong acid cation, strong or
weak base anion and mixed bed media tanks in a number of
varying combinations, to produce the water quality required.
Water qualities of 15 megohm or more, with a neutral pH, can
typically be attained

Some guy’s here run 3 tanks in series. 2 tanks cation 1 anion or 1 cation 2 anion… based on what’s in their water.
Prob more guy’s here run 2 mixed beds in series. 1/2 cube or full… Like john allwashedup runs 2 full in series.

Can’t tell you if they put newly filled tank in 1 or 2 position.

So what your saying is that I can just buy another DI tank and connect it next to the one I have and it will make each one last longer than if separate?

Good question. Just added a second 1/2 cube .

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I’m thinking of rolling with one 1/4 cube cartridge from my cart instead of two. I get about 300 gallons from my cart with two filter cartridges. If I downsize to using only one cartridge how much les water could I expect to get? Would one filter produce 100 gallons? 125?

Perry Tait has that small 1/4 cube filter he sells in one of his videos. Just looks so simple and easy to use.

Golden Eagle is correct by guiding you towards anion and cation mixes to exhaust the capability of your DI RESIN.

Unfortunately, the same cannot be done with Mixed Bed Resin.

Mixed Bed Resin is usually 60/40 Anion/Cation - a formula that is ‘generic’ for most conditions.

The only way to understand the balance of anion and cation minerals in your own water (without a laboratory) is, I think to measure the volume of water through your resin before and after it fails until TDS IN = TDS OUT.

But you can get a guestimate like this :

When your resin fails next time, if your local water was actually 60/40, the resin would fail completely and you would get TDS IN = TDS OUT very quickly.

Usually one side (cation or anion) fails first so you get a ‘fail’ to 60% of TDS IN, or 40% of TDS IN … this tells you which side is failing …

If not, run water through your tank at, say 1gpm - and every 5 minutes check the TDS OUT, if a whole lot of water (hundreds of gallons) passes through the tank before the TDS OUT equalises, then you know there is a chance that switching to separate anion and cation tanks would give you a significantly better result …

If not much passes, you know there would be little gain.

The only mitigating factor is that many of us clean water from several catchment sources, and in doing so, we may be ‘averaging out’ across the different water qualities … but that is too complex to take into consideration - all to save a couple of bucks …

I hope that helps …

I have had an experience twice in the last few weeks that really emphasizes what perry has said. We did some window/Solar cleaning in bad water ares (350 +TDS) and I then tried the same tank in a much better water area (TDS below 50). The TDS in the bad water area was at 6 when we finished the work and when I started in the good water area it dropped back down to 0 TDS. So one side of the mixed bed (anion or cation) was getting used up in the bad water area but the other was not and we were able to continue using the tank for a few more jobs in the good water area.

I want to simplify my set up not complicate it. My gut feeling is that the two tanks/filters run in series will produce a lot more than twice as much pure water than one running by itself. Is that correct Perry Tait (I have TDS over 200)

So what your trying to get at .
Is if 1/2 cube produces 500 gallons of water will two half cubes put together produce 1200 gallons or 1300!gallons

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Ya

First tank will do most of the work, second less.

If you get 500 gallons out of a 1/2 cube. You’ll get 1000 out of 2.
Tank #1 will fail first then take out #2

@500 gallons replace resin in tank #1 Move tank #2 to #1 position

Or replace both at the same time

I don’t understand the logic of why 2 1/2 cubes will yield more than 1 full cube either. I don’t buy it unless somebody can explain it logically.

Perry talked about the mix but I don’t think he addressed how/why 2 1/2 cubes in series can yield more than 1 full cube.

I was disappointed. I hope he comes back to the thread and addresses my original question. I can explain it through my own intuition but that would be based 100% on theory. It lasts longer for sure! I’d like to know how much longer.

Maybe it doesn’t last longer. Haha

The way I see it, a cubic foot of resin has a certain capacity for so much dissolved solids before it becomes exhausted. I don’t see why/how that capacity would change if you divided it up between two tanks. Especially if they’re both a 60/40 mixed bed.

My theory as to what would happen: tank one would exhaust more quickly than a single full cube tank would. But as it starts to exhaust, tank 2 would still be able to produce pure water with the “less purified” water from the first tank. So your second tank will last longer. But essentially the same thing happens with a full cube- the top of the tank exhausts more quickly than the bottom, until the whole tank is eventually spent.

A couple advantages I see to a dual tank setup is:

  1. more warning time to change out your resin. If you have a TDS meter in line after the first tank, you will see when that TDS begins to rise, allowing you to change out the resin in the first tank as soon as it’s fully spent, without worrying about overall water quality suffering.
  2. convenience if you rent/lease your tanks, as you can exchange your spent tank and put the new tank in the number 2 position. No down time, and less headache associated with relying on one rented tank.

So avoiding down-time may save you some money, but regarding actual resin usage, I don’t see how two mixed bed tanks will save you anything over using a single mixed tank.

i think it’s like this:

-tank one does the heavy lifting. it takes the supreme bulk of ions out of the source water.
-tank two provides a final polish, removing whatever’s left of the dissolved solids.
-tank one eventually reaches it’s max capacity for ion exchange
-almost immediately, tank one begins to do the opposite of it’s intended purpose- it starts to release ions into the source water. this creates a situation where tank two is now doing all the heavy lifting, plus it’s dealing with water that’s even worse than the source water.
-tank two is working on it’s own to scrub contaminated water, thus it saturates at an accelerated rate

in a perfect world, tank one’s output would be monitored closely. at a given point (say when it reaches 5ppm output or something), it would be discarded. tank two (which is still producing 0ppm water and has only been exposed to already-low tds water from the start) gets rotated back to the tank one position. a new tank of fresh resin is placed in position two, and we start all over.

in this scenario, none of the resin in either tank is ever tasked with ion exchange of contaminated water.

^that’s all just theory, but it seems to make sense. in this scenario, i could see how a two tank system would outperform a single tank given the same volume for both.

and for the record, in my research i’ve seen this strategy recommended by professionals in a number of industries other than window cleaning, including water treatment facilities, medical applications like dialysis applications etc. so there must be something to it.

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This is pretty much how I see it. Tank one will always be doing ‘standard operating procedure.’

I think that I would rethink this as “4 tanks vs 2” Because 2/1 isn’t probably much different, if at all.

  • It would be an “in the long run” type of scenario.

Good thread, either way, Mike!