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Tds reading 17

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gaz

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Just bought 3 new reverse osmosis membranes 150Gpd each, 10 inch, the tds before resin is 17, but the old ones I've taken out reads 5 before resin. Anyone any ideas why the new ones don't go to 5? I'm not happy with 17 I'll be changing resin everyday

 
The ones reading 5 are too slow so I bought new ones and that way my old ones can be used for an emergency set

 
Flushed it for over an hour it's still the same around 18, put old ones back in back to 5. Don't understand why the new ones don't go to 5.

 
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That's what I bought, the ones reading 5 are black not blue. Bought them from a friend years ago though so not sure where

 
Are they the axeon membrane or a different make? as the one I have are blue but not axeon.

 
Yes they are axeon what are reading 18 they are blue, my old ones reading 5 are black but not sure what they are. Baffled why the pair don't read the same. May as well have thrown my money away.

 
Yes they are axeon what are reading 18 they are blue, my old ones reading 5 are black but not sure what they are. Baffled why the pair don't read the same. May as well have thrown my money away.

 
Sorry I can't give you an answer? what's your tds before Ro and what's your water pressure and also what RO's gpd if you supply your these details maybe the more knowledgable guys may be able to help.

 
Don't think so having more membranes is for producing more pure water not bringing the tds down, think it's better for the more experienced RO guys on here to answer your questions rather than me lol.

 
More membranes would need more pressure to feed all of them at once

I am no expert but i was told in the past that membranes might need bedding in a bit at first

Try running it for a few hours and see if the tds drops

Apart from that i reckon @spruce is the man

He certainly helped me out before

 
I wouldn't have changed them at 5 anyway as that will still be in the high 90%s of efficiency so still working fine

 
They are too slow that's why I changed them, but I've put them back in. Would I get refunded with it only going down to 17?

 
They will be slow due to water pressure etc and the fact that it is a 450gpd

Also the cold temperature will drastically effect the viscosity of the water making it slower and higher tds

 
But it should be same for both sets of membranes, it's the same tap, pressure and filter set

 
I'm presuming your tds meter is working ok. If it isn't you will be loooking for problems that don't exist.

You can buy a bottle of tester fluid with a known tds so you can test your tds meter's accuracy btw. I bought a bottle from www.daqua.co.uk many years ago now.

One of the suppliers once posted on another forum many years ago that 3 membranes was the maximum you could fit on one of these r/o's. I remember it distinctly as I was going to add another membrane and housing to my 450GPD. The reasoning behind it apparently is as @daveyboy noted; the 1/4 hose isn't capable of supplying enough water at the necessary pressure to accommodate this.

I never added the extra housing so have no experience on the outcome. I had considered buying 3/8" or 1/2" prefilters but chose to invest in a bigger r/o at a future time.

My first port of call to identify the problem would be to return the r/o back to its original configuration and check if there's an improvement. (When I posted this initially I thought you had added another housing and membrane. But re-reading the posts more carefully I gather you haven't done this.)

If not, then the things to check are;

Have you got all the wastes joined together correctly? Its easy to get them mixed up.

What about your pure to waste ratio? If more water is going to waste than it should then pressure on the membranes will be reduced and efficiency lost.

If you have then the other option is the test each membrane separately to identify if one isn't performing to standard.

When fitting these membranes its good to smear a very thin film of silicone grease onto the 2 o rings at the back off the membrane so they slide into the housing nicely. If you identify a membrane with a higher tds output, then remove the membrane from the housing, check the o rings for any damage and refit them. Also have a look at the brine seal (the big one in the front and check that and the housing for any issues.

I've heard it said on here that some have experienced a poorer quality of water from replacement membranes. Its taken a few days for them to settle in. Honestly, I've never found that to be the case, but our water isn't hard like some experience, so water hardness maybe a factor.

Added:

No matter what you do those 3 housings RoMan type r/o's will never produce water very quickly. A booster pump may help a fraction. I can't believe how slow they are. We got by for so many years as we have an IBC tank with an automatic shutoff valve. It took us 28 hours to fill an IBC tank in summer and longer in winter. So this is an r/o that may not completely replace your daily drawings so will need the weekend to recover.

I found I was filling my van (650l) on Saturday and son's van (500l) on Sunday for work on Monday. Toward the end of the week we were rationing water so we both had enough to use on Friday.

 
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