RODI question

[rb67]

Hi,
I'm starting up my system after a few years hiatus and want to begin with a RODI purchase.
Trying to get the best value anyone have comments in the Spectrapure refurb systems vs something like a fire water ice like the typhoon 5 ?

Also I would like to hear any low cost ideas about storing water - I have a bio cube 29 so I won't be needing to store too much water...

Thanks
Ron

 

[Fishfinder]

My best advice for storage is a brute trash can. They come in 20gal all the way to 55 gal. At home depot or lowes. I use a BRS RODI it works great. I have no experience with the other options although I heard Spectrapure is awesome

 

[Kershaw]

Brute trash can is a good option. I use one for water changes. But I use 60gal water drums to make my ro water. You could probably get away with just a few of those square 5 gallon water jugs.
I have been using a cheap eBay rodi unit for the last 6 years with out issue. But I also use brs filters in it. Honestly I think the filters mater more then the rodi system it's self.

 

[rb67]

Thanks for the insight maybe I'll go with the refurb

 

[rb67]

Another question:
Is a flush kit really need or worth adding?

 

[Dylan Grech]

Another question:
Is a flush kit really need or worth adding?

Auto flush kits are great for 1 simple reason TDS creep. When water passes through your RO membrane it picks up all the dirt that was left behind when you last used it. The flush kit just throws away that dirty water for you HOWEVER most of the auto flush kits have too short of a timer. To properly flush a membrane takes 1-2 minutes.

Less TDS = less DI used = cheaper water

You can do without a flush kit though just put a Tee before your DI with 2 ball valves and throw away the first 2 minutes of water coming out of the RO after turning on the RODI. Just make sure this dirty water doesn't get in the DI

 

[KStatefan]

I min

Another question:
Is a flush kit really need or worth adding?

In my opinion a flush kit does not do anything to flush the membrane on a home system. I think a DI bypass is a very good thing to have.

 

[rb67]

Thanks - that sounds like a great idea!

 

[Buckeye Hydro Verified Sponsor]

Auto flush kits are great for 1 simple reason TDS creep. When water passes through your RO membrane it picks up all the dirt that was left behind when you last used it. The flush kit just throws away that dirty water for you HOWEVER most of the auto flush kits have too short of a timer. To properly flush a membrane takes 1-2 minutes.

Less TDS = less DI used = cheaper water

You can do without a flush kit though just put a Tee before your DI with 2 ball valves and throw away the first 2 minutes of water coming out of the RO after turning on the RODI. Just make sure this dirty water doesn't get in the DI

Be careful to understand the difference between a flush valve (on the concentrate tube), and a DI bypass (on the permeate tube). They are two very different things that serve two different purposes.

Russ

 

[Dylan Grech]

Be careful to understand the difference between a flush valve (on the concentrate tube), and a DI bypass (on the permeate tube). They are two very different things that serve two different purposes.

Russ

Thanks for your comment. I do understand the difference however from my testing it seems like the bypass actually works way better then the flush kit due to the simple fact that you're monitoring the amount of TDS leaked before switching on the DI stage. The big cavet here though is that a flow restrictor on the drain side of the membrane is kind of a must as the bypass alone would waste way too much water without the restrictor and it also depends on the area.

In my area the tap water line has 1000+ TDS which means I have to run both flush kit and bypass for about 3 mins to reduce TDS down to mid 60s whilst some areas that have a tap line that have a 100 TDS would probably be way better off with just the flush kit.

At this point though I think we might be trying to over optimize so I follow a general rule of thumb:
1) Try a flush kit first preferably an auto one so just in-case you forget to flush your membrane it doesn't just kill your DI
2) If option 1 is not enough go for a bypass
3) If both methods still produce very high TDS then you might want to change the RO membrane
4) If that still doesn't fix it go for a booster pump and slower flow rate membrane
5) If by then you still have high TDS (like I do) then the last resort is to go for a fairly complex system of dual filtration.

The filtration I'm talking about in #5 is where you take the product water from membrane #1 and pass it through a secondary membrane with a booster pump and pressure tank.

With this said I highly doubt anyone in the US will have the issues we face here I've seen a couple of US water reports and you guys never really exceed 500 TDS so dual membrane would be too wasteful.

 

[KStatefan]

The DI bypass is used to remove TDS creep before the DI. This occurs on the clean water side (permeate) Perform this step prior to making DI water.

The flush valve is to help prevent scaling or fouling of the RO membrane by rinsing the membrane with high velocity water. This occurs on the waste water side (concentrate).

 

[Buckeye Hydro Verified Sponsor]

The DI bypass is used to remove TDS creep before the DI. This occurs on the clean water side (permeate) Perform this step prior to making DI water.
The flush valve is to help prevent scaling or fouling of the RO membrane by rinsing the membrane with high velocity water. This occurs on the waste water side (concentrate).

Thank you - This is right on the money! Don't use a flush valve to address TDS creep!
Russ