ro/di still have tds

Let me give you a little history of my RO and RO/DI systems.
I started about 20 years ago with a Watts Premier RO system from Costco or whatever it was called at the time. I am not sure if the Premiers are related or not but I don't think so.
I spent quite a bit of time and money revamping the system to mimic a Typhoon III, better prefilters, better carbons, I even visited Watts Premier and had them upgrade me to a 75 GPD membrane which they bench tested for me. I installed an additional 10" canister and installed a refillable DI cartridge and bought a pressure gauge and TDS meter.

The moral of that story is I had a ton invested and it still only lasted 150 gallons of RO/DI per DI refill no matter what resin I used.

Next I sold that system and bought a real Typhoon III. It still only lasted 150 gallons per DI refill and I was very unhappy since I had invested all that money twice and still did not have what I thought I should.

Next I bought a Spectrapure MaxCap 90 GPD system. I installed it taking the few extra minutes to flush the filters and to trim the capillary tube flow restrictor for my exact water conditions. With absolutely no other changes, my first MaxCap DI cartridge lasted a documented 830 gallons! Success at last.
The first replacement MaxCap DI cartridge went just over 1000 gallons before it started reading 1 on the TDS meter. Better still. The second replacement went just a bit longer and when I talked to Spectrapure they said they had perfected the MaxCap resin blend even further. I was overjoyed.
I upgraded the 90 GPD MaxCap to a dual membrane system capable of 180 GPD and was still getting the same 99.23% rejection rate and DIO was lasting what seemed to be forever, I replaced the first SilicaBuster DI cartridge and a little over 3000 gallons of RO/DI water. I installed a 1" flow meter on the wall just to document the usage.

I was so happy with the MaxCaps I broke down and bought the new at the time MaxCap UHE ultra low waste system. It is running at slightly less tha 1:1 waste ratio and 90 psi pressure with a booster pump. The system is approaching 3 years, yes 3 years old and I am still on the original SilicaBuster DI cartridge and only the second replacement MaxCap DI cartridge.

With RO/DI you really do get what you pay for and cheap is not the answer. It ends up costing you from day one.

When buying a system look for things like low micron absolute rated prefilters, I use a 0.2 micron pleated absolute filter that has 10x the surface area of a normal filter and have only replaced it once in the almost 3 years. I do watch the pressure drop closely using two gauges though. You want a single, yes single not two inferior, carbon block. One 0.5 or 0.6 micron Chlorine Guzzler type carbons is more thansufficient ,even if you have chloramines which is really a burden on the DI not the carbon as many lead you to believe.
You want a quality name brand RO membrane, notice the Premier units do not state the brand name or model number anywhere? Big Red Flag! No secrets, no surprises. If they don't tell you upfront then look elsewhere, its probaby a knock off or no name and probably not ANSI/NSF certified.
Look for a full size vertical DI filled with fresh resin, a minimum nuclear grade or semiconductor grade is good but companies like Spectrapure blend their own resins in house based on thousands of hours of testing, both field or real world and bench testing.

You want an inline pressure gauge so you can watch pressures and pressure drop. You want a TDS meter, either dual inline or handheld, I have multiples of both and prefer the handhelds due to their accuracy and portability, I can test water anywhere I want to not two dedicated locations.
You want a capillary tube flow restrictor you trim yourself, everyones conditions are not the same and there is no one size fits all.

These are just a few pointers on what to look for and there are several good vendors who can provide most of the above. Spectrapure is the only company I am aware of who treats all their membranes with a special treatment then tests them for quality control and ships them wetted. They are also the only company that mixes every ounce of their own DI resins in house.
Check out the ale flyer here:
Untitled Document

But also check out the 75 GPD Premium systems here:
www.buckeyefieldsupply.com

and the reefkeeper here:
Melevsreef.com - Welcome!

and the Optima series here:
FL Aquarium Water Filters Reverse Osmosis Booster Pump GFO Nitrate DI Carbon

All can supply what you need at a competitive price and do not hide anything from you.

"You want a capillary tube flow restrictor you trim yourself"

looked this up. seems it is an insert on the good water out side of the RO membrane. attaches to the 90 degree elbow between the elbow and the 1/4 line. so how do you trim it then? and why? they all say preset. i assume for the true 1:4 ratio that pigtail is trimmed?

also, this may be all in vain. i took my water in to the hospital i work at and checked it in the lab with a tech. they have a tds meter there for the DI systems they use for all the ice machines and it read 0. regardless i will use the advice to "fix" this system to the point that i am satisfied and get 0 tds with the meter i ordered for home use. thanks

p.s. the system i bought has dow filmtec 75gpd membrane. i always email the seller first for info like that, he sent me the info on the prefilters too but i cannot remember all that

The capillary tube flow restrictor looks like a piece of spaghetti with a small flange on one end. It inserts inside the waste line, not good line, and you trim it according to the included directions.
Look on pages 8 through 11 of this manual for the direction on how to calculate your permeate and waste flows and how to trim the restrictor to length.
http://www.spectrapure.com/manuals/P...NDLY/CSPDI.pdf
You would remove your existing restrictor, insert the untrimmed capillary tube, measure the product and waste flows with a measuring cup and calculate the waste ratio. Based on what you find you then remove the restrictor and using a new razor blade you trim it to the total length indicated in the directions. Its really easy and takes just a few minutes. You don't want a preset restrictor, you are no better off than before.

cool, i will order it right now. well, soon. is there a brand to stick with or ones to stay away from? looks like a pretty simple piece of equipment. and just from watching i bet the ratio down there is about 1:8!!!!!

They are $5 at Spectrapure and probably most other places as well, I think Buckeye is close to that too.
I really trust Spectrapure since they exhaustively test everything they sell before introducing it. They depend on their 25+ year reputation in the business. Russ at Buckeye is also a great guy to deal with, I have bought many things from him over the years too.

so the fr-60 or the fr-90 from spectrapure? do i go above or below my gpd fow rate of the membrane. i assume above and trim down?
fr-90 cut to 4 inches it appears.........

If you have a 75 GPD membrane then go with the FR-90. You will not know what to trim it to until you insert it and measure your product and waste flows. It usually ends up like 9" or so on average but everyones conditions are different. It takes into account pressure, temperature, backpressure, TDS and more.

so spectrapure's sheet is a rough guide, what increments should be trimmed at a time? an inch or less? these tubes look really long and their chart states four inches for the fr-90 at 75gpd. also what is the relationship of tube length and water waste? is it the longer the tube the more waste or the opposite?

read it again, it is all based on water calculations. i see the light now. i will grab a graduated cylinder from work tonight and test it.

What you are seeing in the first colum is the mL per minute you will discover once you have installed the restrictor in your system initally, not what it is today or what it should be. You have to install the uncut restrictor, test your product rate, then look that rate up on the chart and trim accordingly.
This is from the Spectrapure Sponsors Forum on some of the various sites:
Flow Restrictor Basics.... - 3reef Forums