[KarlJones]

yes thats right but if I had to guess I would have thought it would have dropped the TDS by 10 or something like that.  I was surprised at 1 TDS.

As you say, the membranes in a RO system do all the work.  So you must change the filters before the TDS rises. If you wait for the TDS to rise then its the membranes and not the filters that are shot.

Back to the DI system. 
Have you considered getting another DI canister, as folks on here have pointed out  you run two in line.  The way this works you basically use your old used resin as a pre filter rather than just throw it away.

It makes more sense as feeding 90 TDS into your new resin is better than feeding 112 into it and saves you a bit of cash by making your new resin last longer.  You could always go for a smaller canister for the pre filter and change the resin in it (just store the old used resin and use it to fill it up) if cash is a problem, but of course, if you got another 7x18 you can just swop them around and re fill the oldest one.

My own system is a bit different to most, I RO it into a water butt and then DI it when I put it into the barrels, it was just easier to plumb it that way.  But I have wondered about getting one of those small 250ml DI jobs for on my RO and just shoving old used resin in it once a week to help bring it down a few TDS before the DI.

[DASERVICES]

Mike,

Do you have a picture of it, or the link which you bought from so we can see what it looks like . If we have that then guys on here can help you resolve it straight away.

Doug

[Mike 108]

D.A.

No. But if I can't sort it this morning I'll take some pictures of the parts and post them on the site.

Thanks

[Mike 108]

Paul Griffin/Macmac/Luke Johnson/D.A.Services/Alex Wingrove/and all

Thanks guys

It's now sorted.

What I'd done was put the resin tube in upside down !!!  (Cringe/embarrassment)

The rubber seal on the tube end which should have been in contact with the lid was at the bottom - the incoming water was just short-circuiting across the lid and coming straight out again!

What a plonker!

For anyone's information, I haven't taken any resin out of the tube yet - it's still full to the top - but everything seems to be OK now. TDS reading 0 ppm.

Alex.  I see what you mean about the sponge - that bit was fitted correctly.

Thanks again guys. Sorry about wasting your time.

Mike

[pjulk]

He He

We all make these silly mistake's at one time or another i have put a di unit back together wrong myself and could understand why the TDS was sky high after i put new resin in.
I took me a day or so to work it out


Paul

[JM123]

I remember someone on here once before put softening salt in the vessel, they couldn't understand why it wasn't bringing the tds down.  suppose we all make mistakes.

[Jason Atwell]

Paul Griffin/Macmac/Luke Johnson/D.A.Services/Alex Wingrove/and all

Thanks guys

It's now sorted.

What I'd done was put the resin tube in upside down !!!  (Cringe/embarrassment)

The rubber seal on the tube end which should have been in contact with the lid was at the bottom - the incoming water was just short-circuiting across the lid and coming straight out again!

What a plonker!

For anyone's information, I haven't taken any resin out of the tube yet - it's still full to the top - but everything seems to be OK now. TDS reading 0 ppm.

Alex.  I see what you mean about the sponge - that bit was fitted correctly.

Thanks again guys. Sorry about wasting your time.

Mike

Hey father in law!! I suppose thats what happens when you get to your age!!!!

[Pat Purcell]

Inspired by this thread I decided to see what happens to TDS after it has gone through the sediment and carbon filters.  The idea was to see if guys that can half justify using DI systems with no RO could benefit from using carbon and sediment filters...

Well my TDS prior to any filtering was 247,  after filtering it was 246.

So no, my thoughts that you might be able to use carbon and sediment filters prior to the DI and cut cost were wrong.  But thought I would post it anyway just incase you were wondering.

I find that strange as well, the DI system we used to have came with a carbon pre filter which was supposed to lengten the life of the resin, I;m not questioning your results I;m just wondering why it was there at all if it didn't do anything

[KarlJones]

Well when I thought about it sort of became a bit clearer.  I should say that there is actually 3 pre filters, 1 sediment and 2 carbon filters that managed to drop it by 1 TDS.

But when I think about it, they are not there to get rid of "totally dissolved solids".  They are there to get rid of solids that are not dissolved, in other words the sort of stuff that will clog up my membranes.

I suppose, the only true way for me to test there effect on DI resin is to run water through some DI resin (250ml) without it being filtered,  and then do the same with it being filtered.  Testing it at 5 liters, 20, 40 and 60 should give a good set of results with my TDS.

This sounds fun to me, so I will do it but it might take me a week or two to get the bits I need.

[JM123]

sediment filter - removes non dissolved solids (sand + silt etc)
carbon filter - removes VOC's (Volatile Organic Compounds) and Chlorine
RO - removes dissolved solids and salts from the water
di - removes any salts/solids which have made it through the membrane.