Another RODI question

[Mrramsey]

Hi all~

I currently run a BRS 5 Stage 150GPD water saver unit. Nothing wrong with the unit its great quality hardware. I do however chew up the DI resin because I only get 96% rejection out of the stock Dow membranes. I am thinking of upgrading to the Spectrapure Spectraselect plus 99% membrane. They are 90gpd membranes and I would need two of them. Would I need to change out the flow restrictors?

I am also open to changing my unit back to a single membrane unit since I don't necessarily need that much capacity. Need to come up with a solution since my DI resin is spent again and I have about 2 weeks worth of top off water stored.

 

[Flippers4pups]

Obvious questions, how often do you run it? How often do you change your pre-filters and carbon blocks? And what's your incoming TDS?

 

[Mrramsey]

Obvious questions, how often do you run it? How often do you change your pre-filters and carbon blocks? And what's your incoming TDS?

Right now about once every two weeks. I store about 24 gallons of RO for top off. My tank is cycled but not stocked so not really on a WC schedule yet. That being said it will end up being about 24 gallons weekly for top off and wc's.

I was going to also have an additional fowlr tank running which is why I chose the larger unit but have since decided not to. Since I do have limited storage capacity the larger gpd production for emergencies is nice as a backup.

I still am on the original prefilters. 1 sediment filter, 1 5 Micron CTO/2 carbon block, 1 0.6 micron + 1 carbon block. Incoming TDS is ~330ppm, ~12ppm after the membranes and just hit 1ppm after the DI.

 

[azjohnny]

I would go to a single membrane and go with the 99% membrane. I am using in my Spectrapure Maxcap and getting very good results. You might also want to upgrade to a Spectrapure DI cartridge.

I looked at the system you have and noticed it had 2 carbon filters and 1 DI. I would change the system so you have 1 carbon and 2 DI filters. If you use a quality carbon filters you only need 1. The micron size of the filters are really big with the BRS, try going to Spectrapures web site and compare filters you will notice a big difference


Here is Spectrapures RC pagethere is a lot of good info in the stickies
http://reefcentral.com/forums/forumdisplay.php?f=229

 

[Flippers4pups]

Incoming TDS IS high, but there is little you can do about that.

How old is the unit and when was the last time the membrane changed?

 

[Mrramsey]

I would go to a single membrane and go with the 99% membrane. I am using in my Spectrapure Maxcap and getting very good results. You might also want to upgrade to a Spectrapure DI cartridge.

I looked at the system you have and noticed it had 2 carbon filters and 1 DI. I would change the system so you have 1 carbon and 2 DI filters. If you use a quality carbon filters you only need 1. The micron size of the filters are really big with the BRS, try going to Spectrapures web site and compare filters you will notice a big difference


Here is Spectrapures RC pagethere is a lot of good info in the stickies
http://reefcentral.com/forums/forumdisplay.php?f=229

Thanks Johnny - Definitely will be upgrading to Spectrapure stuff just trying to figure out which way to go.

Incoming TDS IS high, but there is little you can do about that.

How old is the unit and when was the last time the membrane changed?

The unit was bought New in February of this year.

 

[Flippers4pups]

I'm not familiar with the spectrapure units, but can you back flush the membrane?

Also with your incoming TDS being high, I would upgrade your pre-filters to the finest micron. I would also look in to placing another set of pre-sediment chambers in line pre-membrane.

You should not be going through that much DI!

 

[E Rosewater]

What kind of pressure do you have on the membrane? If it's low a booster pump may help.

 

[Mrramsey]

What kind of pressure do you have on the membrane? If it's low a booster pump may help.

My pressure is fine. I run it at 65psi. In fact I actually lowered my pressure because i discovered that my water pressure was too high at 98psi. Better membranes are the only fix to extend the life of the DI resin. If I can get a true rejection rate of 98% or higher as opposed to the 96% that I currently get it should effectively double the life of the DI resin.

 

[Flippers4pups]

What kind of pressure do you have on the membrane? If it's low a booster pump may help.

Good one rosewater, I forgot about that.

 

[Flippers4pups]

My pressure is fine. I run it at 65psi. In fact I actually lowered my pressure because i discovered that my water pressure was too high at 98psi. Better membranes are the only fix to extend the life of the DI resin. If I can get a true rejection rate of 98% or higher as opposed to the 96% that I currently get it should effectively double the life of the DI resin.

True, but I'm running a BRS five stage unit with a stock membrane and run off around twenty gallons for my ATO and my water changes weekly and still my DI lasts three to four months.
Of course my incoming TDS IS only 40 ppm.

 

[Mrramsey]

True, but I'm running a BRS five stage unit with a stock membrane and run off around twenty gallons for my ATO and my water changes weekly and still my DI lasts three to four months.
Of course my incoming TDS IS only 40 ppm.

what is your outgoing TDs from the membrane?

 

[Flippers4pups]

It will drop to around 10 ppm before DI.

 

[azjohnny]

I'm not familiar with the spectrapure units, but can you back flush the membrane?

Since my feed water in Phoenix is so hard and TDS levels of 750 PPM I run a ratio of 4/1 and manually flush the membrane after each use for about 30 secs. This keeps the membrane from scaling while using hard water, if I had a water softener in line before the RO/DI I wouldn't need the flush kit

 

[Mrramsey]

Since my feed water in Phoenix is so hard and TDS levels of 750 PPM I run a ratio of 4/1 and manually flush the membrane after each use for about 30 secs. This keeps the membrane from scaling while using hard water, if I had a water softener in line before the RO/DI I wouldn't need the flush kit

Yep I manually flush mine before and after each use as well.

 

[shifty51008]

is this tap water or well water? if well water you may have high co2 that could be using up the DI fast.

 

[Mrramsey]

is this tap water or well water? if well water you may have high co2 that could be using up the DI fast.

Nope... city water. There is no co2 present. It is just the high tds and the fact that the stock "98%" Dow Filmtec membrane is only getting 96% rejection. I am sure the reason that I am getting only 96% is my water is somewhat hard.

If you read the fine print on the dow specs for that membrane it states 96%. I did the math and I get exactly 96% rejection.

 

[zoomonster]

I just started using that BRS 150gpd 5 stage a few weeks back. We have moderately hard water here (and my water softener is offline) but I don't have a TDS meter on input side. I have probably produced >300g now between filling tank/sump and daily topoff (high evap). All in all seems to be working pretty well but it will be interesting to see how long the DI lasts.

1) It produces more than 150gpd. I filled my 200g tank in ~day with input pressure of about 75psi.
2) At least for me TDS coming into the DI settled at 4-5ppm and output is still zero TDS.
3) Not exactly measured but waste output looks to be identical to output. So I suppose the "water saver" claim comes from the lower rejection membranes used.
4) The unit was flushed a full hour before use.

The water company has not published a quality report since 2012 but they have been cited for excess TDS more than once with the report listing the tested range at 240-540PPM.

 

[Sammykonga]

300's high?!? Sorry I find this funny cause the TDS here in Phoenix is mid 800's! I have the BRS 4 stage value plus. Like you I like the quality of the unit but am unimpressed with the filters. I plan on switching them to spectrapure. I bought my unit in March of this year and on my 2nd DI cartridge, and it is almost used up. Also I get about 96% rejection too. My plan is to swap out my prefilters and DI foR spectrapure here real soon. I'm going to live with the membrane as long as I can but will be swapping that out to eventually.

 

[azjohnny]

300's high?!? Sorry I find this funny cause the TDS here in Phoenix is mid 800's! I have the BRS 4 stage value plus. Like you I like the quality of the unit but am unimpressed with the filters. I plan on switching them to spectrapure. I bought my unit in March of this year and on my 2nd DI cartridge, and it is almost used up. Also I get about 96% rejection too. My plan is to swap out my prefilters and DI foR spectrapure here real soon. I'm going to live with the membrane as long as I can but will be swapping that out to eventually.

I would swap out the membrane at the same time as the DI, at the rate that you are going through DI it would pay for it self pretty quickly.

Remember for every 2% you improve the membrane rejection rate you double the DI life