[windowwashers]

I have a really high tds out of tap way over 400.

Could I put my old resin that is spent (well at tds 001 before ro to cut down tds, through ro then in new resin and into tank.

Or would this Knacker my ro up?

[Pj]

That will work fine, it won't do any damage to your RO as long as your prefilters are good.  Resin won't last long though, waste of time really, as it will only last a few days.

[Paul Coleman]

I have a really high tds out of tap way over 400.

Could I put my old resin that is spent (well at tds 001 before ro to cut down tds, through ro then in new resin and into tank.

Or would this Knacker my ro up?

Wouldn't you be better off having two DI vessels AFTER the RO meaning that the older resin could protect the fresh resin AND last a decent length of time as well? It would do more good that way than by using it before the RO.  If you were to use FRESH resin before the RO it would only give 1500 litres at most with that TDS.  Partly used resin would give even less.  Then there would be the issue of some of that water going to waste anyway so would at least halve it.  Two vessels after the RO is definitely the way to go if you are going to run a system with two vessels anyway.

[windowwashers]

I guess that was not clear, I am having two after, then a third to use spent resin for before ro (better than throwing it away I thought) does matter how long it lasts as it would get thrown away anyway.

 

[Paul Coleman]

I guess that was not clear, I am having two after, then a third to use spent resin for before ro (better than throwing it away I thought) does matter how long it lasts as it would get thrown away anyway.

 

I suppose it depends on how you define "spent".  If you are calling resin spent at 001 TDS then then it would seem pretty wasteful to me to put it before the RO.  I have three DI vessels.  It wasn't planned that way but just evolved.  I have two of them after the static RO and one attached to the van mount.  The one on the van mount is there on a just in case basis in case I need to get finished miles from home and need to run a bit of tap water through it.  To me this seems more logical.  Another issue though is what happens when water leaving a vessel containing spent resin reaches the same TDS as the tap water.  I have never tried to verify this and it may well be wrong but I've seen it written on here that old, totally spent resin can contaminate water and actually increase the TDS - achieving the total opposite of what you intend.

[Paul Coleman]

theres no need to have more than 2, you will not gain anything from it!

just stick with 2 and when the resin is spent in the first vessel, fill that one with new resin and move the other vessel in front of it, this way you will use your resin completely

Three resin vessels can sometimes be a good idea depending on your situation.  I have two on my static RO as you describe.  I also have a third one attached to my van mount.  It has helped me get finished when working a long way from home by using it to filter maybe 100 litres of tap water.  It's rare that I've needed it but it saved a long trek back the next day to complete some work.

[Paul Coleman]

shiner thats a good idea and something that i've been meaning to get to.

but as far as vessels after ro, then do you agree you only need 2?

tds after ro 10, into 1st vessel out at 0, into 2nd at 0 out at 0. when the tds rises so its coming out of the 1st at 9 or 10 then it's spent (it's not doing nothing) refill this vessel with new resin and swap the 2 vessels around so your newly filled vessel is after your over vessel. continue to repeat process this way then instead of throwing resin away at 1 or 2 tds you use it right up until 10 

Sure thing.  I just use two vessels on the static unit - both after the RO.  As you say, once the water leaving the first DI is the same as the water entering it from the RO, then it's spent.  There is another advantage to having two vessels after the RO as well.  If you are pushed a bit for time, it gives some leeway before needing to change the resin because the second DI vessel will filter it instead.  I do things a bit differently inasmuch that tend to refill vessel 1 and put it back into the number one position.  I realise that I eventually will need to replace the resin in vessel two but not for a very long time.  This may sound a bit odd but there is a very practical reason for this.  When messing about with the RO and vessels, I am in a tight space and vessel 1 is a smaller, lighter vessel than vessel 2.  This means that vessel 2 will only need to be lifted rarely because it will only ever receive water between 0 and 9 TDS.  Even when I need to change vessel 2 (the heavy one), I would be inclined to slot it back into the number 2 position.

[lee_dewing]

you can use water softner, varitech would be able to help you on this;
you probably already know this though.
Lee

[drevitt]

i use 2 di vessells but find the first vessell tds stays at approx 2ppm but the second vessel with NEW Resin in sometimes goes above 2ppm before vessel 1 has gone up ? is there a technique to setting it up so it goes through vessell 1 first or is this scenario just weird

[Paul Coleman]

i use 2 di vessells but find the first vessell tds stays at approx 2ppm but the second vessel with NEW Resin in sometimes goes above 2ppm before vessel 1 has gone up ? is there a technique to setting it up so it goes through vessell 1 first or is this scenario just weird

Sounds like a TDS meter that is slightly inaccurate.  Or maybe you ae taking the reading from vessel 1 and not clearing all the water from the meter before testing water from vessel 2.

[Londoner]

Be a bit carefull about putting too many obstructions in the system after the RO. Everything reduces the output a bit. If your water production is a bit marginal already it may be a consideration.