R O SYSTEMS

[Buckeye Field Supply]

Hi Russ,

 

Is the reason that you want a vertical DI housing to prevent channeling?

 

From our FAQ's:

 

Horizontal DI housings are a design intended to minimize the original cost of the system - you should be prepared for the trade offs. Horizontal DI units typically contain 8 oz. to 16oz. of resin. Typical vertical DI cartridges contain 20 oz of resin. Obviously the more resin contained in the housing the longer it will last and the better treatment it will provide.

 

 

Many horizontal DI housings are not refillable - you'll therefore have to pay for a new housing every time you need to replace the DI resin. The cost of repeatedly replacing the horizontal housing will far outweigh any money saved up-front in purchasing the unit.

 

 

Perhaps most importantly, horizontal DI housings are a less than ideal arrangement for water treatment. DI resin beds shrink/settle through normal use over their life span. You'll note that a cartridge that was full when new can sometimes have a

[Buckeye Field Supply]

a system that delivers water from a pressurized tank to the DI

 

 

Russ: do you mean from my well-pressure tank-house system???

 

 

No - that should be OK. I'm talking about something like the blue tank is this pic that can store pressurized RO water:

 

 

 

 

also, many have said that 100gpd is not efficient???? what size is??? I can use anything from 50-100 gallons in my water changes amongst my fresh water tanks as well.

 

"Efficiency" is a term that is used sort of loosely when people talk about RO systems. There's really two things people are typically concerned with: REJECTION RATE (how much of the impurities in the water does the RO membrane reject) and NOT allow to pass; and RECOVERY (how much of the feedwater ends up as RO water rather than waste water. Let's talk about each one of these rather than "efficiency."

 

 

REJECTION RATE:

 

The higher the membrane rejection rate, the cleaner the RO water will be, and the longer your DI will last. Here are the factory specs on the membranes we deal with most often. You'll see the rejection rate for the 100 gpd membrane is low relative to the others

 

 

RECOVERY:

 

Outside this hobby, "Recovery" is typically expressed as a percentage - it's the percentage of the feedwater that ends up as RO water. In this hobby, the convention is to express this same data as the ratio of waste water to purified water. So for example, a 4 to 1 ratio is the same as a 1/5=20% recovery rate.

 

With all residential scale membranes, the manufactures suggest a 4 to 1 ratio to give you a reasonable membrane life. Can you fiddle with this ratio? Sure.

*If you increase the pressure, the recovery will increase.

 

*If you heat the feedwater the recovery will increase

 

*If you restrict waste water to a greater extent, the recovery will increase.

 

 

 

But, remember that if you increase the recovery (that is, decrease the waste to purified water ratio), you'll likely shorten the life of your membrane.

 

 

Russ

[Buckeye Field Supply]

 

In your specified range the 75 GPD is probably what you want to be looking at, the DOW and filmtec both have ~98% rejection rates.

 

 

Just so people don't get confused, FILMTEC is the brand of RO membranes made by DOW.

 

 

 

Russ

[Buckeye Field Supply]

I was with you all the way until this one. What's wrong with steel?

 

 

It rusts - even if powder coated, the steel brackets will rust over time.

 

 

 

Russ

[Buckeye Field Supply]

I asked the same thing above because I am not sure I understand either... two reasons that I can think of: rust like you mentioned (although I am not sure how much of an issue that is with an RO unit that is generally well away from salt water and anodized or powder coated), and weight... some of these systems can get pretty weighty...

 

Both of the reasons I thought of, though, don't really directly affect the operation of the unit.

 

Right - the rusted bracket just ends up looking sort of scabby...

[Buckeye Field Supply]

Why is sending water from the storage tank to the DI a bad thing??? I have had my system plumbed this way for years...

 

Remember that RO membranes function based upon the differencein the pressure on the feedwater side of the membrane versus the pressure onthe storage tank side of the membrane.

 

So for sake of discussion let