[007 or what]

As you look at the R-O there are two horizontal tubes (with arrows) what is it in them?

I've changed the resin in the blue one b4 but never the arrowed ones.
Please help

[ScrimShady]

the one with the arrows are your ro membrains, they are the ones that seperate the water to pure.

[007 or what]

Do i need to change them?

[Sunshine Cleaning]

Has your TDS reading shot up?
How old are they?
What is the reading after membrane?

[Ian_Giles]

Depending how much water you produce, they will last you a couple of years before you need to change them.

Providing you back flush regularly, and change your pre filters often, they will last a long time.
After a while your TDS after the water has passed through the membranes (but prior to it passing through your blue, resin chamber) will slowly begin to rise.

This WILL happen eventually, regardless of how often you back flush and change your pre-filters, it is then up to you at which point you decide to replace the membranes.

I'm on my second set of membranes (they are the same as yours) and my TDS from then has now climbed to 0.007 ppm, they were reducing the water to 0.001 ppm when they were new.
For me, when the TDS gets to about 0.010ppm I will replace them, they are not particularly expensive.
It is the balancing act between the extra resin you are using against the  replacement cost of the membranes.

Though I may well upgrade to a 4040 R/O as I am now needing to produce more water.

At what point you decide to replace the membranes is entirely down to you

Ian

[matt]

my system is now appraoching its 3rd Birthday

sure i only use 100 - 150 L's a day 3 days a week ( with a occasional sunday morning for comercail )

i havent changed a thing ( apart from some resin every 6 moths ) , my tap TDS is about 460 and it comes out of the RO at about 004 - 005  and the DI sometimes does the rest ( when the DI is changed, as half the time its old and doesnt do anything )