why does adding another membrane increase twice the speed?
- Thread starter Johnb123
- Start date
shifty51008
12-5 Chiefs record
Your basically running 2 units but useing the same prefilters and di for both as long as your not running them one after the other
seamonster124
New member
If you are talking about the BRS upgrade; it takes your waste water and filters it again.
shifty51008
12-5 Chiefs record
It doesnt, it just saves waste water.
The membranes reduce the throughput, so two membranes in parallel allow a higher rate of throughput essentially doubling the output.
Must water feed lines are (in Aus) about 250g per hour allowing plenty of head room for two membranes. The only thing to watch is reduced pressure which will reduce output and efficiency. In some setups you may require a booster pump.
In essence you could run 4 membranes in parallel given enough head pressure and make a massive amount of water.
For those systems that are in series or utilising the waste water from the RO you will find membrane life on that line will be significantly less as it is handling a far higher amount of impurities compared to the original feed water.
HTH
Must water feed lines are (in Aus) about 250g per hour allowing plenty of head room for two membranes. The only thing to watch is reduced pressure which will reduce output and efficiency. In some setups you may require a booster pump.
In essence you could run 4 membranes in parallel given enough head pressure and make a massive amount of water.
For those systems that are in series or utilising the waste water from the RO you will find membrane life on that line will be significantly less as it is handling a far higher amount of impurities compared to the original feed water.
HTH
Essentially, water is pushed through the RO membrane, but dissolved solids and a lot of the water is unable to flow through. The rejected TDS water is sent to the waste water line. If you add another membrane, that water has a second chance to be forced through a membrane to be cleansed. As a result, less water is rejected, and more clean water is produced. If one membrane can do 75 gallons per day, two can do 150 gallons per day. You are still wasting a lot of water though. the 150 gallon systems do a 1:1 ration. So for every gallon of water you make, it rejects 1 gallon as well. 150 gallons flushed straight down the drain. Without the upgrade your rejecting a lot more water than that.
Logzor
New member
It is true that you can achieve nearly a 1:1 ratio with the dual water saving membranes. However I was told that I'm prematurely frying my DI and Membranes since all that extra waste is now being trapped in the system. I may be installing flow restrictors to increase my waste water so I can increase the lifespan on my filters.
outy
New member
DI will only be exhausted quicker because you double production. If you have decent incoming TDS
If you have high TDS incoming its not a good idea because your second membrane is getting higher TDS then normal. Thus spitting out higher TDS then normal.
TDS needs to be checked outgoing behind membranes to make sure your not getting sill high output numbers.
Dual membranes are not wise for everyone.
SNAKEMANVET
PREMIUM MEMBER
I have thought about adding another 150 gpd to produce more water.My water pressure without a booster pump is 105 psi.My tds going in is 14.Could I do another 150 membrane with that pressure.
outy
New member
Your a ideal for it. Crazy not to with low of TDS and pressure.
I like the ebay cheapo membranes, and have great success with them.
I use 2 x 75gpd with a 50gpd restrictor in the winter. I have 27tds incoming and 0 out of my membrane before DI.
SNAKEMANVET
PREMIUM MEMBER
thanks outy.
Buckeye Hydro
.Registered Member
Realize that if you add membranes, and increase the flow through the prefilters, you need to be careful not to push water through the carbon block faster than it can pull out the chlorine. Most 10" x 2.5" blocks are rated at a max flow of 1 gpm, but you'd be better off keeping the flow considerably slower than that. Remember that all your "waste" water and your purified water go through the block.
Russ
Russ
Buckeye Hydro
.Registered Member
Yes - if you plumb the membranes in series. Not my favorite configuration on these little residential units.
Big E
Premium Member
I'm not sure I'm getting how this all works...........
In the configuration where membrane 1 waste goes to membrane 2 input I see how you are saving water but how does the output of clean water double?
You still have a 75gpd restrictor on the at the end of membrane 2 waste.
What am I missing??
I'm asking because I hooked my upgrade kit and my output was the same. I believe everything is hooked up correctly just like the BRS video.
In the configuration where membrane 1 waste goes to membrane 2 input I see how you are saving water but how does the output of clean water double?
You still have a 75gpd restrictor on the at the end of membrane 2 waste.
What am I missing??
I'm asking because I hooked my upgrade kit and my output was the same. I believe everything is hooked up correctly just like the BRS video.
Last edited:
Buckeye Hydro
.Registered Member
Nope - that's not the way it works...
You have twice the membrane surface so you get twice the amount of waste water and twice the amount of RO water. If you use the wrong flow restrictor as a certain popular vendor suggests, you'll get less than twice the waste.
Buckeye Hydro
.Registered Member
When you plumb two low pressure residential membranes in series, you should use a flow restrictor that yields about 4x the amount of RO water produced. With two membranes you have twice the membrane surface and get about twice the RO water.
Big E
Premium Member
Ok, that makes a lot more sense to me, but now I can see how you stated the watch out about the carbon block.
I think I need to call someone
