[windows_chepstow]

I've read numerous posts over the years saying that it's safe to clean windows with pure water with a low TDS reading; for example 2 to 8.

Now, most RO systems will (so I believe) bring tap water down to a low TDS reading; for example a TDS of 2.

So why do we then de-ionise it?

I believe the process isn't exactly 'de-ionisation'; more of an exchange of ions.

Purely out of interest; Can anyone explain in terms that a Geordie would understand; why this 'ionisation' process is so important?

(Before anyone complains; I'm a Geordie!)

[Moderator David@stives]

Tosh

The deionisation is not too important if you can get your tds down to 2 .
I have heard you can clean up to 10 without any problems.

But to be doubly sure it is best to bring it down to zero.

If you could get an ro down to zero ,then there is no need for deionisation at all for the final polishing.

Dave

[Jeff Brimble]

Justin and others have used up to 8ppm tds and some of the Scottish guys (thats a bit more north than Geordie land) have natural tap water with those levels. So if we do have a ban and have to carry water thats where to get it from as it wont need treating. just that you would need petrol sized tankers.

[Mick (UHPS)]

Tosh

Have you read this here

It explains quite a bit about the RO system.

[windows_chepstow]

Tosh

The deionisation is not too important if you can get your tds down to 2 .
I have heard you can clean up to 10 without any problems.

Dave

My RO produces a TDS of 2, and zero after the DI chamber.  But I suspect that the 'Ionisation' part is important.

Mabye it's this process that gives the pure water it's 'agressive' cleaning ability?

One of my customers is an ex-lab technician and she told me that DI water and pure water can be two seperate things and each could give a 000 TDS; at least I think that's what she said.

I know that when you take a TDS reading, what your equipment is doing is trying to pass an electical current through the water and the reading you get is the strength of that current.

I also know that 'pure water' does not conduct electricity.  So if you get a 000 TDS, no current is passing through the two prongs on your hand-held TDS meter; therefore your water is pure.

But I'm interested to find out if there's more to it, and if the Ionisation process somehow makes pure water even more 'special'!

[matt]

ive used mine with TDS at 7 sometimes 8

infact its now 4 (well was last time i checked)

[windows_chepstow]

ive used mine with TDS at 7 sometimes 8

infact its now 4 (well was last time i checked)

So you've got a low TDS, but has your water been through a DI chamber?

Maybe you can clean windows with a low TDS, but only if it's been de-ionised first?  Maybe?

I'm not trying to save on resin, by the way; I've probably got enough to do me for another year or two.

[poleman]

Toss if RO produces a TDS of 2, and zero after the DI chamber the DI chamber is going to last a very long time so cost wise stay with DI chamber as is best to have 0 TDS than 2 when cleaning windows.

Fish tanks use RO water because it takes out many harmful things like lead, copper, calcium, but you could not use water for fish when it has been thought a DI chamber as it takes out all the minerals which they need…(de min system)   

Andy

[matt]

ive used mine with TDS at 7 sometimes 8

infact its now 4 (well was last time i checked)

So you've got a low TDS, but has your water been through a DI chamber?

Maybe you can clean windows with a low TDS, but only if it's been de-ionised first?  Maybe?

I'm not trying to save on resin, by the way; I've probably got enough to do me for another year or two.

yes it has, it getsa to about 7 ish / 8 ish and thats what i normally get out of my RO, thus the resin isnt doing anything, i try to change it at around 5ish, funny really as i use a 500 ml cartridge and i change it every 6 months (or about that) i have 2 of 1 KG bags, thus enough for 2 years at the rate i use it (so its not about saving money either for me )

[Justin Ruggles]

I have gone as high as 015 to clean windows, its strange as its harder to clean at that reading. Its hard to explain really, and only try it if your experinced in WFP cleaning.

Your better off staying as close as 000 as you can. Resin is cheap for RO unit's if you get though a £80 bag once a year then thats nothing, compared to other business costs.

I would recommend you change the pre filters 6 monthly otherwise your membranes will not last so long. Also backflush the system evertime you stop making water. Really easy to do and will again prolong the life of your membranes.

Justin

[JM123]

Hi Tosh, when you pass the water through the resin it is deionisation, reason being that the resin is a mixture of anion and cation resin ( +ve and -ve resins), the positive ions in the resin bond with the negative ions in the water and the negative ions in the resin bond with the positive ions in the water, therefore by the time the water has been passed through enough resin it leaves the water totally deionised ( give or take a few seimens - smaller measure of impurity than tds)

[windows_chepstow]

I've been asking a similar question in a 'Chemical Student Forum' and have been given some answers from a 'professor' or something.

You can read the whole thread here:

http://www.chemicalforums.com/index.php?board=2;action=display;threadid=7832&start=0

(Hopefully you'll get it).

[carl stanton]

like to think i understood it     
intresting reading! so are you any wiser tosh?

[Shine, glasgow!]

good enquiry Tosh
pose them the question
'does RO water with 0 tds act in the same way as DI water with 0 tds'

its like the composition of iron does not change when its magnetised, so water is the same when RO'd or DI'd. However, magnetic iron acts differently, so maybe so does DI'd water
i like techy!
ben

[Rob_Mac]

I run a 300gpd unit with a pump I have a reading of 102 on the pressure gauge.

This has produced 000 pure water ( from the RO only) for over 4 months now.

The inline tds meter is reading 002 but the handheld is reading 000

No final polish required

Rob

[carl stanton]

where from midas how many stages

[Rob_Mac]

The unit is from RO-Man, 3 stage.

I dont think it has anything to do with the unit, more with the pressure.

Rob

[dai]

Tosh, surely 0 TDS means there are no total dissolved solids present, if there are no dissolved solids, there is nothing that can be left on the glass when the water evaporates. That's all we want. Irrespective of whether it come out of an ro or Di unit.
Tosh if your urine was o TDS you could clean windows with it. Dai

[windows_chepstow]

Tosh if your urine was o TDS you could clean windows with it. Dai

I actually saw a Big Brother celeb drink his own urine after he'd processed it twice through a RO unit on some Sky programme; weird science, or science abuse or something.

But as far as I understand, 0 TDS doen't exactly mean the water has no impurities.  I think there are certain things a TDS meter won't detect.

I just wondered if the deionisation process was critical to washing windows.  Just maybe all the protons were positively charged which meant the dirt, normally negatively charged, was attracted to the pure water; or something just as ridiculous.

I'm sure we've all been amazed at how easy cleaning 'something dirty' with pure water seems to be.  Some types of dirt just 'melts' away.

As it turns out, because there's no impurities in the 'pure water', it's just a better solvent.

[windows_chepstow]

good enquiry Tosh
pose them the question
'does RO water with 0 tds act in the same way as DI water with 0 tds'

ben

Ben,

I think I've asked them enough naff questions.

But your question, in once sentance, is what I've been asking in paragraphs.

Go on, join the chemical forum, introduce yourself, and ask the question.

I'd be interested to find out.

Regards,

Tosh