RO/DI System pressure Dilemma

[Airwolf]

I’m grateful to receive all of this great input so thank you¡ I’m curious >while I wait for my booster pump to show up would it be “illegal” to pump my first 30ish gallons with 40 psi?? Let me know¿¡

You will be fine. I did. Just know it will take a while and waste a bit more water.

 

[Klyle]

As stated in that thread the necessity in home systems is debated. A lot of it has to do with everyone's source water makeup, and how you pre-filter prior to your membrane.

If you have a lot of sediment and aren't using a .35 or below micron pre-filter I'd say highly recommend to flush. If your pre-filtering down to a .2 micron sediment pre-filter it's unnecessary. Most people don't use less than a 1/0.5 micro sediment pre-filter to my knowledge. I think 1 is probably the most common from threads I've read on here.

The purpose of the flush is to force out any sediment that may be on the surface of the membrane before they are allowed to clog up pores, which would reduce your efficiency. So obviously the less sediment you put into your membrane the less necessary it is to flush it.

I advise people to use it as the 30-60 seconds of flushing isn't going to harm your membrane in any way, not flushing could harm your membranes given the proper conditions. The amount of harm will vary based off how much Sediment you force into the membrane, a little bit isn't going to make a difference, but a lot will.

One example would be not purging your carbon blocks. The amount of carbon fines that will dump on a membrane will no doubt shorten it's life. Performing a flush will purge most of those off the surface of the membrane instead of forcing them deeper into the membrane and causing them to break down which will clog more pores as they lodge deeper into the membrane. Now without performing that flush all those carbon fines would embed into the membrane over time shortening it's life.

So as a precaution without knowing the specifics of someone's water source/slit values, and which rating (nominal/absolute; 1, 5, 10 micron, etc.) filter cartridges they use I recommend it as a better safe than sorry approach.

If it's just about saving a couple cents in water, I don't know about you, but I waste more on stupider stuff than 60 extra seconds of flushing my membrane. My water is cheap @ ~ 2¢ a gallon so the extra 1-3¢ for a 60 second flush doesn't bother me from a financial standpoint.

Now if you pay more for your water, are in an area where water isn't as available or are facing drought conditions, I completely understand wanting to preserve the extra 60 seconds of water, and it very well may be safe for you to skip the flush.

So @Opus isn't wrong, the necessity of a purge is more often than not over rated, but the extra step isn't going to do any harm.

Thank you for the clarification! Very much appreciated

 

[ying yang]

I’m grateful to receive all of this great input so thank you¡ I’m curious >while I wait for my booster pump to show up would it be “illegal” to pump my first 30ish gallons with 40 psi?? Let me know¿¡

Not sure I understand what you asking about being illegal and pumping at 40 psi while waiting for your booster pump,( if you waiting for pump then you have no pump at moment ha ha ) as said above you can make water at 40 psi ,it will just take longer,waste little more water possibly etc.
I know in emgland with the current " water regulations" if add any pump to your water system then should inform " water regulations " reason for this if everyone had pumps taking more water from cold water mains then " it may not be able to keep up/ supply" but chances of everyone adding a pump is unlikely and mains pipes are way over sized so even though I'm a plumber and heating engineer I notified no one ^_^
Me personally if I was you,I would be thinking my reef tank I plan to keep for years so waiting a few days - to a week until booster pump gets delivered ,then I add booster pump to my rodi unit, I would think its only relatively small amount of time so would just wait till got pump .
I think you only just setting up your reef tank and waiting on water,so if in no rush for water like no livestock already in system then would just wait till you got the booster pump installed but entirely your choice.
And you very much welcome,anything to help each other is my thinking ^_^

 

[Spare time]

Position a is the flush position. I leave mine in that position for about 90 seconds before and after making water.

+1

I also recommend bypassing the DI resin when doing this

 

[Opus]

+1

I also recommend bypassing the DI resin when doing this

This is flushing the membrane, not bypassing the di resin.

 

[Opus]

One example would be not purging your carbon blocks. The amount of carbon fines that will dump on a membrane will no doubt shorten it's life. Performing a flush will purge most of those off the surface of the membrane instead of forcing them deeper into the membrane and causing them to break down which will clog more pores as they lodge deeper into the membrane. Now without performing that flush all those carbon fines would embed into the membrane over time shortening it's life.

That hasn't been my personal experience. I never purged my carbon blocks for 20 years and I still got 5+ years out of my membranes.

 

[Airwolf]

This is flushing the membrane, not bypassing the di resin.

Correct. But you can bypass your DI resin by pulling the line out of your DI input or putting a three way valve in. This would help with the TDS creep at the start of water production.

 

[Woodyman]

That hasn't been my personal experience. I never purged my carbon blocks for 20 years and I still got 5+ years out of my membranes.

That's impressive. We had a new person at work one day install 2 new carbon blocks and kill a membrane. Membrane was sitting around a 97.5% average rejection rate for the month prior. A week later 2 new carbon blocks were installed and we were sitting at 94%.

Only change attributed to the system during that time was 2 new carbon blocks that we learned were never flushed. Now this is an industrial system not a home unit. So we're talking about 20" carbon blocks not 10".

That's just my experience with past dealings. Milage will vary of course.

Now in theory most of the carbon should be large enough to get flushed as rejected brine anyways, but I've always played it safe.

 

[Woodyman]

Correct. But you can bypass your DI resin by pulling the line out of your DI input or putting a three way valve in. This would help with the TDS creep at the start of water production.

That is how I took the comment from @Spare time as well. Since it was an 'also' bypass the resin.

 

[Spare time]

That is how I took the comment from @Spare time as well. Since it was an 'also' bypass the resin.

Yes I was referring to having the, initial very high tds, water that normally leaves the membrane bypass the DI resin and into the drain to prevent burning through the resin. I stopped using resin for a while until a realized this was happening (I had a tds meter pen and not an inline meter at that time )

 

[Opus]

Yes I was referring to having the, initial very high tds, water that normally leaves the membrane bypass the DI resin and into the drain to prevent burning through the resin. I stopped using resin for a while until a realized this was happening (I had a tds meter pen and not an inline meter at that time )

That is what makes this whole conversation confusing to many. By-passing the di is referred to a lot as flushing the membrane which it is not the same thing, at least I've never interpreted it that way. In any case, I wasn't trying to offend anyone. I thought the statement was for the OP about moving the switch from open/closed and by-passing the di, and in this case the OPs switch was not for that function.

 

[Spare time]

That is what makes this whole conversation confusing to many. By-passing the di is referred to a lot as flushing the membrane which it is not the same thing, at least I've never interpreted it that way. In any case, I wasn't trying to offend anyone. I thought the statement was for the OP about moving the switch from open/closed and by-passing the di, and in this case the OPs switch was not for that function.

All good haha