[rich fraser]

These membranes

As the topic states. These membranes are approximately 6 months old and I’m struggling to get TDS below 35. Operating pressure when producing water is 65psi. I’m running a cbm240e booster pump which is nearly 10 years old so possibly this needs replacing. Pre filters carbon and sediment changed regularly. 4040 housings we’re soaked in a bleach bath for an hour when the membranes were last changed(as recommended by Vin). Not sure if to throw  money at new membranes or booster?

[Perfect Windows]

The way June at Gaps talked about it (and hence what I've relied upon), it's a slimy feel if it's biological. That green tinge doesn't look too healthy, though.

The bleaching needs to take in the whole water route from tap all the way to the output from the RO (so prefilters and pump). I've always left it 24 hours but a stronger solution might not need as long.

65psi makes me think you don't really need to worry about the pump.

On the question of prefilters, I cannot recommend too highly a DI vessel 2/3 full (never more) of activated charcoal, followed by a particulate filter (though that's belt and braces; the charcoal seems to filter particles as well as remove chlorine). The guys change theirs every ten months or so (22" vessels) and I change mine every year (35").

Vin

[rich fraser]

Cheers Vin.
How do you know when your activated charcoal is spent? Where are you getting it from? I’m currently producing my water on a static unit, approximately 2000 litres of pure per day Monday to Friday.

[Richard Groves]

What tds were you producing when they were new ( 6 months ago ) ?

[Perfect Windows]

Cheers Vin.
How do you know when your activated charcoal is spent? Where are you getting it from? I’m currently producing my water on a static unit, approximately 2000 litres of pure per day Monday to Friday.

I don't really know when it's done for, so I'm pessimistic.

The charcoal is from GAPS, acid washed activated charcoal.  Three annual fills for me, four for the guys so don't be scared by the price: http://www.gapswater.co.uk/acatalog/Activated-carbon--acid-washed---25-kg--50-litres--6951.html

With your usage you'd be replacing more often but I'm not an expert on this - a word with June might be an idea.

There are chlorine test meters around but you'd need to use it pretty much daily unless you went double DI of charcoal and tested between the two DI's. That'd give you leeway not to test every day. https://www.amazon.co.uk/Chlorine-tester-measuring-instrument-quick-up/dp/B007XE3X96

Vin

[rich fraser]

What tds were you producing when they were new ( 6 months ago ) ?

I was getting TDS of 15 at first. When I changed them the year before I was getting the TDS down to 6 and they lasted twice as long.