Ro membranes

[bmattivi]

I have a PUR Clean RO system, I have dual 40" RO membranes, I seem to only get about one year of life out of these membranes, I just changed the charcoal in my charcoal filters yesterday but I am making more RO water than reject water which is usually a sign the membranes are going bad right??? Can I clean them or do I just have to change them out again, the membranes backwash every 4 hours, any suggestions on extending the life of the membranes. I had an RO system from Coleman at my car wash I sold and I think I changed the membranes once in 12 years

 

[Dcalhoun]

I have the same system and the same problem with membranes. I can't speak to the ratio of RO and reject as it relates to membrane quality but I typically see problems with my product water quality when the membranes are failing. I have talked with a few 'experts' and they tell me it is a function of the hardness in our water supply. But, we soften the water before it goes to the RO system, so....

 

[MEP001]

If they're fouling, there's something wrong with your softener or there's something in the water. If the water to the RO unit tests 100% soft, then try an ultra-fine prefilter to catch smaller particles.

If the product volume is increasing and the quality is dropping, your charcoal filter could be defective. Test for chlorine at the RO reject because it will be concentrated by the production and easier to detect in small amounts.

Your RO system isn't supposed to backflush. It may have a flush, but it's supposed to be just water running at no pressure. If someone has plumbed something to reverse-flush the membranes, that is what's destroying them.

For your own benefit, don't cross-post the same question in multiple threads. It's easier for people trying to follow what's going on to read one thread than split up replies in two different ones.

 

[bmattivi]

You are correct my bad the RO system does not backwash but does run at no no
pressure, it does say backwash on the seimens unit inside the control box
and it does run water into the RO tank at no pressure 4 times per day. I do
have a high TDS number on my city water (don't remember the number and have
no test kit for this) nothing I can do about that. I test the chlorine on
the output water every week and water hardness every other week. I may run
1 grain hard on water and my chlorine level is zero

In your opinion is it unusual to have a higher RO water production than
reject water amount of water

I have never tested the reject water for chlorine level only the RO product
water being delivered to the bay

The ultrafine filter might be the answer due to the high TDS number but
where would this be installed within the system

No way to clean the RO membranes I assume and extend the life is there?

 

[MEP001]

You should never have more product than reject. If it's like that even after replacing the membranes, the system is adjusted wrong. If it recirculates a portion of the reject to get a higher system flow, it should run 1:1 reject to product. If it dumps all reject to drain, it should be a minimum 2:1.

As I mentioned before, test the RO reject for chlorine. There will not be any in the product because it gets filtered out.

TDS is dissolved solids, not particulate. A finer prefilter will make no difference just because of a high TDS. You might try one anyway, and if you notice it getting clogged in a short time you'll extend the life of the membranes. Ideally you should have a pressure gauge just before and just after the prefilter to see if it's fouled and restricting flow. A prefilter would be on the incoming line to the system before the pump and membranes.

You can clean the membranes, but in my experience it always results in an increased TDS.