[mjm]

I have a 40.   40 pumped system from pure freedom.   I used to have  a 400 ltre pumped system but can't remember when I changed the membrane on it reading wise

I have had  the  40 40.     3 or4. Years   the reading is  jumped to 15. From 7.   
In a week.     With new filters    what is the highest.   You have. Gone  Before.   Di.   When you have changed the membrane

[SB Cleaning]

I have a 40.   40 pumped system from pure freedom.   I used to have  a 400 ltre pumped system but can't remember when I changed the membrane on it reading wise

I have had  the  40 40.     3 or4. Years   the reading is  jumped to 15. From 7.   
In a week.     With new filters    what is the highest.   You have. Gone  Before.   Di.   When you have changed the membrane

I change mine at 25

[mjm]

I have a 40.   40 pumped system from pure freedom.   I used to have  a 400 ltre pumped system but can't remember when I changed the membrane on it reading wise

I have had  the  40 40.     3 or4. Years   the reading is  jumped to 15. From 7.   
In a week.     With new filters    what is the highest.   You have. Gone  Before.   Di.   When you have changed the membrane

I change mine at 25

Alright thanks. Iam not sure if I flushed it or not.  So I have many months. Yet.

[Spruce]

I have a 40.   40 pumped system from pure freedom.   I used to have  a 400 ltre pumped system but can't remember when I changed the membrane on it reading wise

I have had  the  40 40.     3 or4. Years   the reading is  jumped to 15. From 7.   
In a week.     With new filters    what is the highest.   You have. Gone  Before.   Di.   When you have changed the membrane

Whats your tap water tds?  You need to find out how well your membrane is performing. Many years ago a supplier told me to start to consider a change when the membrane reaches 94% rejection rate. You need to decide when the cost of resin starts to make the purchase of a new membrane worthwhile. 
If your tap water tds is low then you could probably leave it a bit lower than that percentage.

[mjm]

I have a 40.   40 pumped system from pure freedom.   I used to have  a 400 ltre pumped system but can't remember when I changed the membrane on it reading wise

I have had  the  40 40.     3 or4. Years   the reading is  jumped to 15. From 7.   
In a week.     With new filters    what is the highest.   You have. Gone  Before.   Di.   When you have changed the membrane

Whats your tap water tds? You need to decide when the cost of resin starts to make the purchase of a new membrane worthwhile.

My TDs jumps a bit.  310.  To. 370. Max

[mjm]

Good point spruce.  Iam going to tinker about with it tomorrow,,,  👍

[Spruce]

Good point spruce.  Iam going to tinker about with it tomorrow,,,  👍

Perhaps a good flush and adjust waste to pure ratio until you get the lowest tds output from the membrane.

At 370ppm your output of 15 is still a rejection  rate of 96%. At 310 your rejection rate is 95%.

For it to jump up from 7 to 15 in a week would appear to be a waste to pure ratio adjustment needed.
I'm not saying it is but it's where I would start.

Yours is a typical example of needing to watch your membrane output because of your high tap water tds. Going from 7 to 15 theoretically doubles the cost of resin.

For me my 4040 has a rejection rate of 97% with a tds of 3. I could let mine increase to 10. At 10 I would be running at a rejection rate of 92%. It would mean my resin costs would increase by about £45 a year.
While it isn't much compared to the cost of a new membrane,  I loathe changing resin. The other issue is that resin has become scarce as I have always used Tulsion.

It's all about"economies of scale."
Do I spend £326 on a new Axeon hf5 membrane to save £45 a year on resin, bearing in mind that those resin costs are going to increase (escalate) as the membrane's efficiency deteriorates.

My membrane is 7 years old btw.
 

[david mark]

Just changed mine it lasted  8 years

[Spruce]

Just changed mine it lasted  8 years

I'm also aware that when they start to fail, they fail quickly.

[mjm]

Well I have flushed for an hour. And a half
I've got it back to 008.    Pumped.   Before di.     But unpumped it's 20.
 It's the first time.  I have took a reading.  With the pump off.   So I'd this about right

[H2GoKent]

Well I have flushed for an hour. And a half
I've got it back to 008.    Pumped.   Before di.     But unpumped it's 20.
 It's the first time.  I have took a reading.  With the pump off.   So I'd this about right

I manufacture water for others at my unit using two pumped RO's, post membrane ours is about 12-15 but our tap water is 350-400 ppm very chalky. My business H2Go in Kent has around 9000 litres of storage so we use a lot of water

I would flush frequently , and if you use softened water it means the membrane will last longer.

[mjm]

Iam going to flush more often.  Thanks for your replies