RO line pressure

[eric.tech]

Good morning from MI folks!

Looking to get some opinions on RO line pressures and booster pumps. A little back story on what I’m running into: our water out of the tap here is at a really high TDS, 570, and I just installed a BRS 200gpd water saver kit on my existing RO system. Due to the high TDS source water and the nature of running two membranes in series, I’m getting about 13 TDS (97% rejection rate) after the membranes, but before the DI stages. After the DI stages, I have 0 TDS.

My question is I have around 70psi/4.8bar of line pressure coming into the RO system. Would it be worth the additional cost to add a booster pump to bump the pressure to 80psi/5.5bar to get a bit more efficiency out of the membranes? Just trying to cut down on DI resin usage as much as possible.
I’ve though about running the membranes In parallel to reduce the TDS, but the high cost of sewer/return water here prevents that. I’ll most likely be running them in series to avoid excess waste water down the drain. Thanks for any thoughts on this!

 

[Doctorgori]

We have the same issues: tap water TDS 400 - 800 ppm
I tried the water saver setup with the two membranes but was told that above a certain TDS. it doesn’t work efficiently or sumthin like that.
At those pollution levels I burn through resin at any PSI .... it made a difference going from 40 - 50 PS!, I use the Coraline booster gadget ....it did save me some resin overall
Also splitting the Anion & Cation helped, as depending on whats in. the water sometimes one goes way faster than the other

 

[eric.tech]

We have the same issues: tap water TDS 400 - 800 ppm
I tried the water saver setup with the two membranes but was told that above a certain TDS. it doesn’t work efficiently or sumthin like that.
At those pollution levels I burn through resin at any PSI .... it made a difference going from 40 - 50 PS!, I use the Coraline booster gadget ....it did save me some resin overall
Also splitting the Anion & Cation helped, as depending on whats in. the water sometimes one goes way faster than the other

I went the same way as you did with the separate resins and my anion always burns up faster. I may try the booster just to see if it helps and maybe learn how to regen the DI resin to extend how often I actually have purchase it. Maybe I’ll run the membranes in parallel while the weather is warm and use the waste water to water the garden and during winter switch it back to series...

 

[Potatohead]

Get a booster pump and plumb it after the sediment filter and before the membranes. Pump it up to 90-95 psi. You are going to need huge pressure in order to make this work, your second membrane is receiving around 900 TDS. Even with 98% rejection you'll still get a decent amount of TDS into the DI. It may be cheaper to just pay for more waste water, to be honest.

 

[eric.tech]

Get a booster pump and plumb it after the sediment filter and before the membranes. Pump it up to 90-95 psi. You are going to need huge pressure in order to make this work, your second membrane is receiving around 900 TDS. Even with 98% rejection you'll still get a decent amount of TDS into the DI. It may be cheaper to just pay for more waste water, to be honest.

I’ll have to do some calculations, but I live in a very small town that happens to have a municipal water supply. What that boils down to is our sewer and water costs are pretty high out this way, typically $100 a month due to how few people there are paying for it. That’s very high compared to what I used to pay in a different city in the area where I lived, usually $75 a quarter At that location. Sewer is the killer unfortunately, so it may end up being a wash between DI resin or added cost of dumping waste water down the drain in the winter. I’ll give the booster pump a shot and see how it works out. If I use a lot of resin still, I’ll give the regen process a shot.

 

[Doctorgori]

I went the same way as you did with the separate resins and my anion always burns up faster. I may try the booster just to see if it helps and maybe learn how to regen the DI resin to extend how often I actually have purchase it. Maybe I’ll run the membranes in parallel while the weather is warm and use the waste water to water the garden and during winter switch it back to series...

Sat what? regenerate resin? can we deviate for a second? whadda know? VERY curious, apologies in advance

 

[Doctorgori]

I’ll have to do some calculations, but I live in a very small town that happens to have a municipal water supply. What that boils down to is our sewer and water costs are pretty high out this way, typically $100 a month due to how few people there are paying for it. That’s very high compared to what I used to pay in a different city in the area where I lived, usually $75 a quarter At that location. Sewer is the killer unfortunately, so it may end up being a wash between DI resin or added cost of dumping waste water down the drain in the winter. I’ll give the booster pump a shot and see how it works out. If I use a lot of resin still, I’ll give the regen process a shot.

We pay more for water in Cleveland than we did in Phoenix, go figure

 

[eric.tech]

Sat what? regenerate resin? can we deviate for a second? whadda know? VERY curious, apologies in advance

Check out this article:

http://reefkeeping.com/issues/2008-09/nftt/index.php

 

[mann1139]

So I had the same issue. My TDS out of our well is incredibly high (1,200 TDS), so I had to look into more uncommon solutions. I even talked to the pros at AWI and Buckeye Reef Supply for help. Since I was already running 2 membranes, BRS had the suggestion of 'splitting' my system in two.

I used to run 2 membranes in a true 'series' setup, meaning the good water from the first fed the second (not the hybrid series setup where the waste from the first feeds the second). The problem was that the second membrane had almost zero pressure on it, so it couldn't filter properly.

My new setup is a saltwater mixing station with three tanks, and 2 separate RO systems. The first one has pre-filters, a booster pump, and the first RO membrane. That flows to a holding tank.

The second system has an old, cranky booster pump which pumps water out of that holding tank, through a second RO membrane, and then through the DI cartridges into a second holding tank.

It works beautifully. I used to fret about whether I would be able to make enough water before the DI cartridge, which was getting water in the teens, burned out.

Now the first membrane takes the water from 1,200 down into the 20-30 range. The second takes it down to 4, and the DI cartridges are happy.

 

[eric.tech]

So I had the same issue. My TDS out of our well is incredibly high (1,200 TDS), so I had to look into more uncommon solutions. I even talked to the pros at AWI and Buckeye Reef Supply for help. Since I was already running 2 membranes, BRS had the suggestion of 'splitting' my system in two.

I used to run 2 membranes in a true 'series' setup, meaning the good water from the first fed the second (not the hybrid series setup where the waste from the first feeds the second). The problem was that the second membrane had almost zero pressure on it, so it couldn't filter properly.

My new setup is a saltwater mixing station with three tanks, and 2 separate RO systems. The first one has pre-filters, a booster pump, and the first RO membrane. That flows to a holding tank.

The second system has an old, cranky booster pump which pumps water out of that holding tank, through a second RO membrane, and then through the DI cartridges into a second holding tank.

It works beautifully. I used to fret about whether I would be able to make enough water before the DI cartridge, which was getting water in the teens, burned out.

Now the first membrane takes the water from 1,200 down into the 20-30 range. The second takes it down to 4, and the DI cartridges are happy.

Now that is an interesting take on it. I’m assuming you run the sediment filters and carbon blocks on the initial membrane and then maybe just a sediment filter and the DI stages on the second?

 

[mann1139]

Now that is an interesting take on it. I’m assuming you run the sediment filters and carbon blocks on the initial membrane and then maybe just a sediment filter and the DI stages on the second?

Yes on the first. 1 sediment and 2 carbon, plus the filters on the entire house.

No need for any pre-filter on the second membrane, since it is receiving the 20-30 TDS water that the first membrane output.

 

[eric.tech]

Yes on the first. 1 sediment and 2 carbon, plus the filters on the entire house.

No need for any pre-filter on the second membrane, since it is receiving the 20-30 TDS water that the first membrane output.

right on. If the booster pump doesn’t help lower the tds to an acceptable level, I may just give that a shot!