[a900]

I'm measuring my pressure after the prefilters and just before input to membrane housing.  My Pump gives good pressure but it's not translating to good tds. Hmm  I'm using a hf5 membrane. Would be happy with 15. Would half my resin use.

I'm wondering if the prefilters are somehow restricting the water flow to the membrane. The other day I connected the pre filters only to the tap and they took much longer than the tap only to fill a bucket. I mean double the time.
Altho when everything was plumbed back up I'm still getting good system pressure with the pump on?

[Dave Mills]

OK, measuring at the important point - thats good.  How old are the prefilters?  Are they bunged up?  Try swapping them or reseating them. With a pump you should be getting much better flow through.  Much better.

[a900]

The filters are new. About a week or 2 old. As is the membrane.

They have been out and checked that they look right and sealed right. They look fine.

[Frankybadboy]

WHERE DID YOU GET THE MEMBRAINE FROM

[Dave Mills]

Do you have the booster after the filters?  Ours is before on the basis that I want the water to get through the filters at the maximum rate.

I am running out of ideas, tbh.

[a900]

Yesterday I moved it from before the membrane and after the pre filters to before everything in an effort to make a difference.

On flush how much slower does your water come out compared to the tap?  Wondering if I've got a flow restriction somewhere and I'm still getting pressure but not the flow required

[Dave Mills]

On flush with the booster its just over double the flow of the tap without the booster pump.

[Chris - CBWC]

Yes it should be run for 10 to 20 mins before taking this reading and it will settle but having said that I've been getting 30 Tds from 350 as well, love to no how people get 10 and below. 
What system is it?

Is this on 100% waste for 10-20mins prior to every fill up/top up?  I flush my ro for probably less than that today, maybe 5 minutes, and only when I started to close the waste to run it back through the ro did it gradually start to decrease (starting at 255), rather than the immediate decrease I was expecting (should be at around 19 going into my di).

So do I flush it for much longer than I have been?  Otherwise I'm sitting with measuring jugs and a TDS meter waiting for the level to drop before I can plug it back into the DI!  Too fiddly and cumbersome.

[Dave Mills]

Quite a bit of bad advice is given on here about flushing. Flushing will not affect your TDS - it will affect your throughput.  Not my words, those of June at Gaps.

I flush monthly  for 20 minutes and suffer no problems at all (about 12,000 litres of pure output at that point).  Throughput is the same as when new (12 months) and output TDS is exactly the same as two days after I put in the membrane.  I think I am helped by the fact that I use a DI vessel of charcoal as a pre filter.  Nothing at all gets through.

[jk999]

What do you mean do vessel full off charcoal can you explain more please

[Dave Mills]

DI vessel (the one you would normally use for resin, I mean) 2/3 full of acid washed charcoal (Gaps sell it).  I also have a particle filter after it as a tiny bit of charcoal can pass out even though its acid washed.  The vessel is a 36 inch one and it has lasted a year - I will be filling it shortly.

The charcoal is £90 a sack but I will get about 2 years out of it.  About 144,000 litres of pure, so about 720,000 litres filtered for £90.  Worth it to keep the membrane in great condition.

[wightsurf]

@ Dave Mills

Have I got this right > you don't use pre filters only the charcoal and particle filter
before membrane ?
I ask as im going to upgrade hopefully this year.

[PoleKing]

Ive got the similar to you Dave.
Ionic do a charcoal filter, sealed unit, same size as their RO unit think its about £90. Says to change after 500,000 litres.
All I've got is the charcoal, then a polyphosphate filter (Dual Pumps, Melton Mowbray, £15 each) then RO then resin.
Works a treat. Change the polyphosphate quarterly.

[Avo]

Quite a bit of bad advice is given on here about flushing. Flushing will not affect your TDS - it will affect your throughput.  Not my words, those of June at Gaps.

I flush monthly  for 20 minutes and suffer no problems at all (about 12,000 litres of pure output at that point).  Throughput is the same as when new (12 months) and output TDS is exactly the same as two days after I put in the membrane.  I think I am helped by the fact that I use a DI vessel of charcoal as a pre filter.  Nothing at all gets through.

i must say June knows her stuff she helped me out a few times when having problems with ro's...

[Dave Mills]

@ Dave Mills

Have I got this right > you don't use pre filters only the charcoal and particle filter
before membrane ?
I ask as im going to upgrade hopefully this year.

Yes.  From booster pump, into one of these - http://www.gapswater.co.uk/acatalog/SPECTRUM-composite-vessel-complete-with-head--riser-and-screens--8--diameter-3496.html

2/3 filled with - http://www.gapswater.co.uk/acatalog/Activated-carbon--acid-washed---25-kg-2193.html - Do not overfill!

Output into one of these - http://www.gapswater.co.uk/acatalog/No.20-2G-Standard-Industrial-plastic-filter-housing--20---3-4--BSP-ports-2901.html with a 20" particle filter

Then into 4040 membrane.
 

[wightsurf]

Thanks for the links. I have a spare Di unit so could I use this for the washed charcoal?
Also is there such a thing as 10inch particle filter?(is it the same as the ones I use now) as I could use my present ro unit for this then all I would need to get is the 4040 membrane and housing.

[Dave Mills]

Thanks for the links. I have a spare Di unit so could I use this for the washed charcoal?
Also is there such a thing as 10inch particle filter?(is it the same as the ones I use now) as I could use my present ro unit for this then all I would need to get is the 4040 membrane and housing.

Yes, and yes.

http://www.gapswater.co.uk/acatalog/GE-purtrex-filter-cartridge-2877.html

[wightsurf]

Thanks

Last Q.
Where is the cheapest place for the housing ? and will my present ro unit booster pump work for this new set up?

Ok 2 Questions 

[jk999]

Dave how big is the bag off washed carbon

[Matthew Broadhead]

I had this same issue. Try backflushing the system for 5 or 10 minutes before and after use then check after letting it run through for a few more. I was getting 30 or 40 from a tap output of 200. Now I get about 5. 0 after it goes through the di   also check your tds meter hasnt got a bit off dirt on it that you havnt seen.