[jr windows]

I've had a merlin for 2.5 years. I have changed the top filter but haven't changed the other 2. My tap tds is 237 and out of the merlin is 007.

Cheers jason

[Mike_G]

It says in the manual you should change pre filters every six months and the ro every couple of years ( i think) but if it is coming out at 007 I would not bother.

[jr windows]

Cheers Mike, it seems slower than it used to be.

Thanks Jason

[leapstallbuildings]

I've had a merlin for 2.5 years. I have changed the top filter but haven't changed the other 2. My tap tds is 237 and out of the merlin is 007.

Cheers jason

If yours is like mine, the top one is a carbon pre filter anyway so would need changing more frequently than the lower two which are membranes.  My merlin has been installed now for about 20 months.  It was giving a very healthy 006 from 200 tap water.  Unfortunately I had to restrict the waste.  The RO is on someone else's property and the waste goes into a ditch.  They wanted the waste reduced due to mosquito problems.  So I put a flow restricter on it and the TDS went up to 017.  It means that I have to change the resin a bit more and it may shorten the life of the membranes but at least I don't have to move the unit elsewhere.
It sounds like your Merlin is doing just fine.  I wouldn't bother changing the membranes until they slow down a lot and the TDS shows a rapid climb.  You'll know soon enough when to change them.  Probably a good idea to have a couple handy so that production doesn't get interrupted.

[cybersye]

sorry to hijack, but whilst on subject of merlin, I tried advertising a spare merlin housing a while back (now obsolete as I have a 4040 ) . I still have it for sale if anyone is needing a spare.

[Mike_G]

I have two pre filters and one membrane!

[jr windows]

Mike,
Are the filters new? And how much do you want for them.

Cheers jason

[leapstallbuildings]

I have two pre filters and one membrane!

Think I better clarify.  Although I have two membranes on the Merlin (the lower two housings), I also have two pre filters.  The carbon pre filter is in the top housing of the Merlin unit.  The sediment pre filter is in a free standing 20 inch housing which is just before the Merlin unit.  I also have a pre filter before that as well to filter out iron.  During flooding a couple of years ago, there were issues with my previous RO (a 300 GPD effort).  Apparently there was high iron content in the water which wasn't there before the flooding.  The iron levels are normal these days but I've left the pre filter in place.  Doesn't seem to be doing any harm.