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So here's some early morning jargon and math for you. If your Feedwater is 280 ppm, and your permeate (RO water) is 85 ppm, then your rejection rate is 1 - (85/280) = 1 - (0.30) = 0.70, or 70% You want the rejection rate to be something north of 95% - meaning the membranes would be rejecting...

Better quality RO systems will come with a coiled up cable with bare wire leads labeled "prefiltration" or something like that for this purpose. Or some will have contacts on the controller where these switch wires can be connected. Check your manual. If none of those things exist, we install...

This is a microswitch installed on the carbon tank valve. A two conductor cable runs from the switch to the RO, and signals the RO to shut off if it is running when the carbon tank goes into backwash. This is especially useful if there is a high likelihood of the RO running when you have the...

You should be getting more than a year out of your membranes. The use-able lifespan of the membranes is most affected by your pretreatment - what you do to the feedwater before it reaches the membrane. In your case: Contact your water utility and see what they use as a disinfectant. It will...

Here are the three common Max Flow (aka "Big Blue") housing oring styles. The orings are NOT interchangeable among them. Does one of the three match yours? We should have all three in stock.

That housing takes a 4.5" x 10" filter (nominal). There are many brands of that housing, and the oring size is not standard among brands. Is there anything on the housing to tell you what brand it is? We have orings for three brands in stock.

Yes they would - that's one reason it is so important to pretreat for scale forming minerals like calcium and magnesium (aka hardness). Yes - "recycle" refers to taking some of the concentrate and routing it back to the intake side of the pump. Some lower-end RO's include a recycle function...

For softened municipal water, and an RO system with 2 to 4 4040 membranes plumbed in series, a good rule of thumb is to set the concentrate to 3+ gpm and set the recycle for half that amount.

Certainly not typical.

Assuming you have them plumbed in series, go no lower than 3 gpm on the concentrate, and if you're at membrane spec pressure and temperature, you should be at about 2500x3=7500/1440=5.2 gpm permeate. adjust this equation if the membranes aren't 2500 gpd, and for your pressure and temperature.

Minimum recommended concentrate flow on a 4" diameter membrane or series of 4" membranes is 3 gpm.

The ratio of permeate to concentrate is affected in a big way by the quality of your feedwater. Let's start there. Is your feedwater less than 1 gpg hardness?

So for the housing that is fed directly from the pump... the water enters from the bottom so the brine seal should be at the bottom. The reject from membrane one feeds the top of membrane 2. So for membrane 2 the brine seal should be at the top. I can't really tell from your photos, but...

The black seal at one end of the membrane is called a "brine seal." In your photo above, the feedwater would come from the left, and would try to force the brine seal open, which makes it contact the inside of the membrane housing. The permeate comes out of the central stem - either end. If...

BINGO!

The key to minimizing concentrate flow is proper pretreatment - meaning the RO feedwater should be less than 1 gpg hardness.

No - it means they will meet factory spec output at a lower pressure. Often 100 psi membranes of the size we're talking about here are referred to as "low energy membranes," and 80 psi membranes are referred to as "extra low energy."

Chris - welcome to the world of RO's. I have lots of questions for you to troubleshoot the system and pinpoint any issues. Even if those membranes were changed out a day before you bought the place, if that RO hasn't run in a year no doubt the membranes are fouled (and they may or may not be...

Roger... message was intended for those interested in buying it.