Advice RODI Units???

[diamondreef]

Just found 10 percent off an rodi unit on bulk reef supply... brs 4 stage value plus..75 gpd... is that the one everyone prefers? Lol

 

[AZDesertRat]

No.
They do not supply an inline pressure gauge, use very coarse 5 micron nominal rated sediment filters (you can see 40 microns with the unaided human eye so 5 microns nominal is much worse than 1 micron absolute), use a 5 micron 6,000 gallon carbon block versus a 1 micron 12,000 gallon block, do not treat nor test their dry off teh shelf you get what you get RO membranes, do not beldn their own DI resins for maximum performance and life and do not use the much better capillary tube flow restrictors. There really is a difference, look closely at the differences and what you are getting yourself into. it will cost you more to own and operate in the first year alone so what appears a good deal really is not.

 

[robbrouse]

This is a debate I can see. Mine been running for about 18 month (the BRS one) and I have changed the settlement filter twice and the carbon and DI one time. I've always got 0 TDI... No saying they are the best but they do work and I did not find the cost of operation that might,. Yes I get 4 to 1 waste water but my water out of my tap sucks.

 

[AZDesertRat]

Where it becomes apparent is when you monitor your rejection rate or removal efficiency. Since the RO membrane is the workhorse of the system and does 90-98+% of the work it really makes a difference. Spectrapure specialy treats ALL of their RO membranes so the rejection rate is improved as is the GPD slightly. For every 2% you gain in rejection rate you double the life of your DI.
If you are only monitoring the final RO/DI TDS you will not notice the difference as you wouldn't know any better. But, if you monitor the rejection rate and compare the normal 96-97% most users see to the 98+% the Spectrapures average (mine is 99.3%) you see the DI would last twice as long or longer.

The other big difference is the long term life of the RO membrane. When you protect it with a 1 micron or less absolute rated filter versus a 5 micron nominal rated filter then you set and monitor the waste ratio yourself rather than depending on a "one size fits all" fixed restrictor that may or may not be correct for your exact water conditions, the membrane will last many times longer so costs you less over the life of your system. My membrane is over 5 years old, I make a lot of water with two reefs and a sump and ATO, my tap TDS is around 550-600 most times and I have to use a water softener and its still over 99% rejection ratewith no signs of letting up when most systems, my old AWI Typohoon III included, get 18-36 months tops. I got 14 months out of a previous membrane and 18 months out of another before the rejection rate went through the roof before switching to Spectrapure. Their 28 years of experience pays off.

 

[robbrouse]

Do you work for the company?

 

[AZDesertRat]

Nope but I have been a certified water and wastewater treatment plant operator and manager for 38 years and now work for a top 10 environmental engineering firm as a project manager, comissioning and testing water treatment plants and training operators. Treatment and membranes are my profession and I recognize quality when I see it. Having owned 6 RO/DI systems personally and having many in the plant labs I have a very good understanding of the subject.

 

[robbrouse]

Dang, you have the stuff to back it up.. Just kidding.. Like I said they seem like fine units, but mine had not failed me and since I'm not looking for a replacement I'll stick with what I have. And yes I would suggest it to anyone.

 

[AZDesertRat]

What is your rejection rate? Have you calculated it? What is your exact waste ratio? These are very critical numbers you need to know as too little waste and your membrane wil not be sufficiently flushed and fail sooner and if the rejection rate is not up where it should be you could be trhowing money away on DI to make up for it. They may not be immediately apparent but it will come around one day andcould bite you if you don't keep up with it. Again, you get what you pay for, and pay for and so on. The DI that lasts you 6 months may really last a year and the membrane that needs replacing at 2 years may actually last 5-7 years or longer. Randy Holmes Farley reported 10 years on a Spectrapure membrane on RC a few years ago which not many can claim. Better filters and better membranes save money. My $800 MaxCap UHE paid for itself in less than 3 years compared to a normal RO/DI in water and sewer savings, filter savings since it uses about 1/4 the water due to its 1:1 was ratio, longer membrane life and much longer DI life. I did a write up on a couple of the forums on my first 5 years of usage and exactly what I have spent in that time and it amazed even me on what it has saved.

There is a difference and research and development pay off versus assembling some off the shelf components.

FYI, you can now get tested RO membranes from Buckeye Field Supply too so it is catching on. That added 1 or 2% or more rejection rate really adds up. Buckeye also uses 1 micron or less sediment filters too so the membrane and carbon block are well protected and last longer.

 

[robbrouse]

My rejection rate is 4 to 1 in the summer and 2.75to 3.5 in the winter. Mine performs better the colder the water is...

So if I were to replace my filters with the Spectrapure would that be enough. IS there something else in there system I do not know about?

What is the PSI you need to run the 90 gallon membrane? Mine is at 50 PSI right now....

 

[AZDesertRat]

Colder water does treat better and will give you lower TDS so DI lasts longer but as you noted the waste ratio goes down.
Yes you can replace your filters, they are all standard size. The most important piece is the RO membrane, your may be performing well or it may not, a TDS meter will tell you this info. If its 97-98% now leave it alone. If its lower than that you might want to change it to gain efficiency and DI life. 50 psi is sufficient to operate a membrane, Dow Filmtec rates them at 50 psi for comparison purposes. 40 psi is about the bare minimum if you expect any efficiency but they perform well up to 150 psi or higher, its the housings and fittings that are the weak point. I run my booster pump at 95 psi to improve the rejection rate and increase the GPD myself.

 

[robbrouse]

Rat, this is where you lost me.. The water coming out of the RO is always at 2 and out of the DI is always 0. And yes seems like in the summer my waste water is higher than the cooler months. It's been a few months since I've double checked this.

With the higher PSI do you have more or less rejection rate?

 

[AZDesertRat]

To know how well the membrane is working you need to know your tap water TDS and calculate your rejection rate. You need 3 TDS numbers to trubleshoot a RO/DI, tap, RO only and final RO/DI. As water cools it becomes more dense or the viscosity is higher so it is harder to get through the membrane fabric. Less contaminants get through so the rejection rate goes up . In summer as the water warms up it becomes more fluid so passes through the membrane easier, carrying more TDS or contaminants with it. Some people make the mistake of warming their water up but that is counterproductive since it exhausts your DI quicker due to the higher RO only TDS. It is better t leave the water cold and live with the reduced GPD but better quality or add a booster pump which raises the GPD and actually improves the rejection rate even more since membranes love pressure almost as much as they do softened water which is the best thing you can do for an RO membrane since it does much of the work for it, kind of like pretreatment.

 

[TerryLowe]

Looking at the refurb now. What kind of TDS meter do you suggest?

 

[bigfoot86]

BRS 5 stage here. You'll be just fine with it. No issues whatsoever.

 

[Masterpiece Corals]

I use a vertex, works just fine.

 

[AZDesertRat]

A good TDS meter is the HM Digital TDS-4TM, TDS-3 or their new AP-1 series. All are ATC or auto temp compensated unlike the inlines so are very accurate and have built in digital thermometers so serve dual purpose.