[mac74]

Hi, what TDS number would you let your resin get to before changing it?
Also what Reading straight off the R.O would make you change the R.O itself?

Thanks m

[Spruce]

Hi, what TDS number would you let your resin get to before changing it?
Also what Reading straight off the R.O would make you change the R.O itself?

Thanks m

For me; 1ppm. I know that I can see tiny spots on our lounge window in the early morning sun at 5ppm.

When to change the membrane/s?  This is your decision and will very much depend on your resin costs and the cost of the replacement membrane/s.

At one time, the suggested guideline was when the efficiency of the membrane dropped to 94%. But if you are in a hard water area, then you could decide to change the membrane sooner due to the higher cost of resin. Conversely, if you are in a soft to medium water hardness area, then you might leave it a little longer.

This is all about "economies of scale." What might work for me may not make sense to you.

[NBwcs]

I change mine when it gets over 5, never had a call back yet. I couldnt tell you  at what tds reading i change the membranes, its more a case of the frequency of which im having to change the resin, when it gets very frequent ie  twice a week its time to change the membranes. My present ones seem to have lasted ages.

[mac74]

Hi, what TDS number would you let your resin get to before changing it?
Also what Reading straight off the R.O would make you change the R.O itself?

Thanks m

For me; 1ppm. I know that I can see tiny spots on our lounge window in the early morning sun at 5ppm.

When to change the membrane/s?  This is your decision and will very much depend on your resin costs and the cost of the replacement membrane/s.

At one time, the suggested guideline was when the efficiency of the membrane dropped to 94%. But if you are in a hard water area, then you could decide to change the membrane sooner due to the higher cost of resin. Conversely, if you are in a soft to medium water hardness area, then you might leave it a little longer.

This is all about "economies of scale." What might work for me may not make sense to you.

Hello Spruce, thanks for the reply.
Tbh I normally let the resin go to 10ppm before i change it, and never had any complaints. The r.o i normally change when it hits around 28. As a kid i used to live up near yourself red/mrske where i bet the water has a low tds, but i now live just outside of london where the tds is 420ppm. I think im going to double DI it!

[mac74]

This may sound silly, but can the resin tds ever climb higher than the R.O tds output?

[AuRavelling79]

This may sound silly, but can the resin tds ever climb higher than the R.O tds output?

Not unless there is some contaminant between RO and Resin chamber.

[Spruce]

Hi, what TDS number would you let your resin get to before changing it?
Also what Reading straight off the R.O would make you change the R.O itself?

Thanks m

For me; 1ppm. I know that I can see tiny spots on our lounge window in the early morning sun at 5ppm.

When to change the membrane/s?  This is your decision and will very much depend on your resin costs and the cost of the replacement membrane/s.

At one time, the suggested guideline was when the efficiency of the membrane dropped to 94%. But if you are in a hard water area, then you could decide to change the membrane sooner due to the higher cost of resin. Conversely, if you are in a soft to medium water hardness area, then you might leave it a little longer.

This is all about "economies of scale." What might work for me may not make sense to you.

Hello Spruce, thanks for the reply.
Tbh I normally let the resin go to 10ppm before i change it, and never had any complaints. The r.o i normally change when it hits around 28. As a kid i used to live up near yourself red/mrske where i bet the water has a low tds, but i now live just outside of london where the tds is 420ppm. I think im going to double DI it!

It would certainly make sense to double di the pure to get to most from your resin.

I very much doubt that a customer would notice those spots at 5ppm tbh.

Our water on Teesside is around 125ppm so pure from my 4040 before di is 3ppm.

One of the suppliers back in the early days suggested I didn't need to use resin at all.

6 litres of resin lasts me about a year, but then I don't do that much work these days.

I did leave changing resin once. My TDs after di suddenly went from 2ppm to 5ppm. So I now just change resin when it gets to 1ppm after di.

But as I say: this is what I do. My axeon hf5 membrane is 11 years old and still has a rejection rate of 97%. In this regard we are very fortunate. Things could well be vastly different living in your neck of the woods.

This is why it can be very difficult to give advice that covers all scenarios. You have to take on board only what makes sense to you and your environment and forget what doesn't.

[Lee GLS]

I gave up using resin over 10 years ago. RO only I replace the RO when it gets to roughly 25ppm.

[AuRavelling79]

I gave up using resin over 10 years ago. RO only I replace the RO when it gets to roughly 25ppm.

Interesting. My RO (Merlin equivalent) starts at about 7/8 then after a year is at low to mid teens depending where the input TDS is. (When we've had a dry spell it is 350 plus, if we've had a fair bit of rain it's about 275 plus)

Then I have a small resin chamber.

I change when the out put into the tanks hits 12. Because it has mixed with lower TDS in the tanks it is between 5 and 10 in the van tank.

I feed two other window cleaners ( they chip in on costs) and none of us have had complaints.

[Spruce]

This may sound silly, but can the resin tds ever climb higher than the R.O tds output?

I believe this can happen. My reasoning (and it's not based on any scientific base) is that resin attracts the tiny dissolved solids that are so small they pass through the membrane. Resin (mixed bed) is made up of a mixture of cations (+) and anions (-). Dissolved metal ions have a positive charge and are attracted to resin anions with a negative charge.

https://sciencenotes.org/cations-and-anions/

https://www.bbc.co.uk/bitesize/guides/zj38scw/revision/1

Once those cations and anions have attracted all the dissolved solids they can, the resin is spent. Once the resin is spent, I believe that some of those attracted ions can be released back into the water flow as the electrical charge of the anion and cation ions are depleted.

My inline tds meter registered 5ppm of water after the di with 3ppm going in before I changed the resin.

[Spruce]

I gave up using resin over 10 years ago. RO only I replace the RO when it gets to roughly 25ppm.

Cation ions are most common to cause spotting as they are minerals like calcium, lead, etc. If your water supply is low on these metals, then you will be able to use water with a higher tds to clean with, without issue.

So when the question is asked regarding how higher tds can I clean windows with, no definitive answer can be given as the composition of water will vary from catchment area to catchment area.

We have found that Tulsion MB115 works well for our water supply. But, according to Doug Atkinson, some of his customers prefer MB111 which has a different cation to anion ratio mix.

Doug stated many years ago; "MB-115 is a ratio of 1.5 with the anion side more loaded. If your water structure was 1.3/5 anion loaded, then both resins would deplete at the same time. If all of a sudden you had an imbalance and your water became 1/1 then the cation would deplete first." 

For me, 5ppm is when I noticed tiny spots on the lounge window in the early morning sun. I doubt a customer would notice them. I used a backpack and mixed pure water with tap water. I didn't notice an issue with 4ppm, but I did with 5ppm. Hence, the decision to replace resin when it reached 1ppm after di.

[NBwcs]

I gave up using resin over 10 years ago. RO only I replace the RO when it gets to roughly 25ppm.

Cation ions are most common to cause spotting as they are minerals like calcium, lead, etc. If your water supply is low on these metals, then you will be able to use water with a higher tds to clean with, without issue.





So when the question is asked regarding how higher tds can I clean windows with, no definitive answer can be given as the composition of water will vary from catchment area to catchment area.

We have found that Tulsion MB115 works well for our water supply. But, according to Doug Atkinson, some of his customers prefer MB111 which has a different cation to anion ratio mix.

Doug stated many years ago; "MB-115 is a ratio of 1.5 with the anion side more loaded. If your water structure was 1.3/5 anion loaded, then both resins would deplete at the same time. If all of a sudden you had an imbalance and your water became 1/1 then the cation would deplete first." 

For me, 5ppm is when I noticed tiny spots on the lounge window in the early morning sun. I doubt a customer would notice them. I used a backpack and mixed pure water with tap water. I didn't notice an issue with 4ppm, but I did with 5ppm. Hence, the decision to replace resin when it reached 1ppm after di.

Thats interesting, which water authority covers where you live Spruce?

[Spruce]

I gave up using resin over 10 years ago. RO only I replace the RO when it gets to roughly 25ppm.

Cation ions are most common to cause spotting as they are minerals like calcium, lead, etc. If your water supply is low on these metals, then you will be able to use water with a higher tds to clean with, without issue.





So when the question is asked regarding how higher tds can I clean windows with, no definitive answer can be given as the composition of water will vary from catchment area to catchment area.

We have found that Tulsion MB115 works well for our water supply. But, according to Doug Atkinson, some of his customers prefer MB111 which has a different cation to anion ratio mix.

Doug stated many years ago; "MB-115 is a ratio of 1.5 with the anion side more loaded. If your water structure was 1.3/5 anion loaded, then both resins would deplete at the same time. If all of a sudden you had an imbalance and your water became 1/1 then the cation would deplete first." 

For me, 5ppm is when I noticed tiny spots on the lounge window in the early morning sun. I doubt a customer would notice them. I used a backpack and mixed pure water with tap water. I didn't notice an issue with 4ppm, but I did with 5ppm. Hence, the decision to replace resin when it reached 1ppm after di.

Thats interesting, which water authority covers where you live Spruce?

Northumbrian Water.