[AuRavelling79]

I've got a 300gpd Roman 10" type of RO.

When I replace the membranes they start off bringing down the TDS from about 330 to about 10 - 15 and then underneath the membranes the final chamber is resin which brings it to zero. Worked for nearly ten years fine by replacing membranes, filters and resin as needed.

The membranes are now producing at about 23 and I've ordered some new ones. But the resin doesn't seem to do much - or rather it does intermittently.

I filled the 10" chamber last week and it didn't change the TDS after the RO. So I discarded the resin and refilled (from the same bag) and it came down to 000 for about a week and is then crept back up.

Changed the resin last night but not making much difference - in at 23 out at 18. Doesn't make sense it should be 000 for a while at least.

Possible reasons?

1. I wonder if the washer on the resin chamber has compressed and water is leaking past - but I cannot tell. Any thoughts?

2. TDS meter is playing up - batteries haven't been replaced for a while.

3. Thought it might be the resin but it was OK on the last attempt but one, but not the one before that.

Help please.

[Walter Mitty]

Hard to say really.
Batteries on TDS meter sounds a possibility. The other stuff does sound inconsistent.  Possible crack or partial blockage in the resin vessel's riser tube?  Do you have another resin vessel that you could connect up to use as a "control experiment"?  Is the riser tube seated properly?  Maybe purchase a second resin vessel as a "failsafe" and connect it in series?
Re-reading this, I'm not so sure that you have the type of resin chamber with a riser tube.  Is
the resin chamber an integral part of the RO unit?
Although you shouldn't have to, I'm wondering about you getting a second resin vessel to connect up in addition.

"I've got a 300gpd Roman 10" type of RO."

Maybe a Greek one would be better?  (Sorry - bad joke)

My RO takes the water down to about 008.  I have two resin vessels after it.  Although this sounds like overkill, I had the vessels already from a previous way of setting things up so figured I may as well make use of them.  I change the first one (the smaller) every few weeks and the second one, rarely.  It saves having to check the TDS too often.

[AuRavelling79]

@Walter Mitty

Thanks; I have changed the batteries - same reading and yes the resin chamber is part of the RO unit. Looking at it you have the three membranes on top and the left chamber of the three hanging down is where the resin goes. Not a lot to go wrong really.

I'm going to fiddle with the seating washer - put it in boiling water, to soften it and try again.

Malc

[AuRavelling79]

Sorted! Added another sealing washer. Back to 000

Obviously the water was seeping past and so however it came out the RO it went into the tank.

[Walter Mitty]

Sorted! Added another sealing washer. Back to 000

Obviously the water was seeping past and so however it came out the RO it went into the tank.

Great stuff!  Glad that you're sorted.