fishmanmike01 Posted February 22, 2015 Share Posted February 22, 2015 I watched a BRS segment today that suggests running a second membrane in series will double the output and cut waste in half at the same time. I run a 75 gpd membrane and adding a second would basically make it a 150 gpd. How is this different than just changing to just a 150 gpd membrane to begin with? Opinions? Quote Link to comment Share on other sites More sharing options...
TheClark Posted February 22, 2015 Share Posted February 22, 2015 Possibly one benefit is that the waste water from membrane one turns around and goes through a second membrane. In theory cutting the waste water in half. I have no experience though with the 150 GPD membranes. I am running that BRS second membrane and it was a breeze to setup. It made 180 gallons in 19 hours a couple days ago or about 127 Gallons Per Day. One other difference, the second membrane requres allot of water pressure. I had to go to my pressure reducing valve on the water supply and up the pressure a tad. Quote Link to comment Share on other sites More sharing options...
fishmanmike01 Posted February 22, 2015 Author Share Posted February 22, 2015 (edited) Possibly one benefit is that the waste water from membrane one turns around and goes through a second membrane. In theory cutting the waste water in half. I have no experience though with the 150 GPD membranes. I am running that BRS second membrane and it was a breeze to setup. It made 180 gallons in 19 hours a couple days ago or about 127 Gallons Per Day. One other difference, the second membrane requres allot of water pressure. I had to go to my pressure reducing valve on the water supply and up the pressure a tad. What pressure are you running? My other concern/confusion is most setups I've seen only have the fast flush at the end of the series. Wouldn't this force all the scale and whatnot from the first membrane into the second? Wouldn't you really need the ability to flush both? Makes sense to me. Edited February 22, 2015 by fishmanmike01 Quote Link to comment Share on other sites More sharing options...
Blue Z Reef Posted February 22, 2015 Share Posted February 22, 2015 From what I've read you go from a 1:4 good to waste ratio to a 1:1 with dual membranes. You will still have a 1:4 if you go 150gpd vs dual. The main issue as stated is pressure. I run a single 150 and have to have 60 psi in to the membrane to be efficient. It's likely similar for dial 75s. I was going to go dual 150s but my dang booster pump died so I'm stuck with the inefficient for now :( Quote Link to comment Share on other sites More sharing options...
fishmanmike01 Posted February 22, 2015 Author Share Posted February 22, 2015 Another way to look at it though is a single 150 gpd would also "save" waste water simply because its not running as long as 75 gpd. I'm sure I'm wrong but it seems more confusing than it should be. Quote Link to comment Share on other sites More sharing options...
Bombertech Posted February 22, 2015 Share Posted February 22, 2015 Food for thought, depending on your incoming TDS, Sediment/Carbon/DI is an option. I crinched the numbers last Friday on usage based on an incoming TDS of 43ppm. A square foot of mixed bed DI resin would run about 8,500 gallons of water. Came out to 4.9 cents a gallon as I recall. Now, someone running the Dual Membrane RODI needs to cross reference to see what is more economical. For me, living in the high desert, water is expensive so cutting down on backwash (wastewater) is very important. Oh, and Buckeye Hydro is who Bulk Reef Supply gets their parts from in case anyone wanted to cut out the middle man or customize their water filtration setup. 2 Quote Link to comment Share on other sites More sharing options...
Blue Z Reef Posted February 23, 2015 Share Posted February 23, 2015 Food for thought, depending on your incoming TDS, Sediment/Carbon/DI is an option. I crinched the numbers last Friday on usage based on an incoming TDS of 43ppm. A square foot of mixed bed DI resin would run about 8,500 gallons of water. Came out to 4.9 cents a gallon as I recall. Now, someone running the Dual Membrane RODI needs to cross reference to see what is more economical. For me, living in the high desert, water is expensive so cutting down on backwash (wastewater) is very important. Oh, and Buckeye Hydro is who Bulk Reef Supply gets their parts from in case anyone wanted to cut out the middle man or customize their water filtration setup. Haha I wish I only had 43 in, ours is 110 on a good day. My resin goes out pretty quick even with a nice membrane. Thanks for the tip on Buckeye, I'll have to check them out! Quote Link to comment Share on other sites More sharing options...
icepikbiker Posted February 23, 2015 Share Posted February 23, 2015 I feel lucky the highest I've seen my TDS going in is 23 and my normal water pressure from my washer "Y" is 90 PSI at my RO/DI unit. I haven't changed my filters in prob over a year, I really should check my membrane tho, TDS coming out is still 0. I refill my 5 gal top off every 3-4 days and around 500 gallons in WCs, so roughly 1000 gallons a year. My LFS charges $.50/gal for RO/DI $1/gal for Mixed Saltwater I bought the unit used and put all new filters and membrane in it, about $100 total. I also rent my place so I don't pay for water So I've save about $400 with my RO/DI unit, and that's just in FW. 1 Quote Link to comment Share on other sites More sharing options...
fishmanmike01 Posted February 23, 2015 Author Share Posted February 23, 2015 Oh, and what's with the suggested water temp of 77 degrees for maximum efficiency. Who the heck can feed water that warm constantly? Quote Link to comment Share on other sites More sharing options...
icepikbiker Posted February 23, 2015 Share Posted February 23, 2015 I've heard of some people putting the whole unit into a tub of hot water. Quote Link to comment Share on other sites More sharing options...
Bombertech Posted February 23, 2015 Share Posted February 23, 2015 If you are having issues with the membranes due to temperature , wrap 50-100ft of poly around your hot water tank and insulate. 1 Quote Link to comment Share on other sites More sharing options...
fishmanmike01 Posted February 23, 2015 Author Share Posted February 23, 2015 (edited) If you are having issues with the membranes due to temperature , wrap 50-100ft of poly around your hot water tank and insulate. I'm not, but that's a smart idea!i feed my unit with a tee off of the cold water inlet to the water heater! Edited February 23, 2015 by fishmanmike01 Quote Link to comment Share on other sites More sharing options...
fishmanmike01 Posted February 23, 2015 Author Share Posted February 23, 2015 Is there such a thing as too hot? I could feed from the hot side. Quote Link to comment Share on other sites More sharing options...
Bombertech Posted February 23, 2015 Share Posted February 23, 2015 Yeah, too hot isnt good either. You could mix it! Quote Link to comment Share on other sites More sharing options...
fishmanmike01 Posted February 23, 2015 Author Share Posted February 23, 2015 Yeah, too hot isnt good either. You could mix it! That's an idea. Y from both feeds. Quote Link to comment Share on other sites More sharing options...
icepikbiker Posted February 26, 2015 Share Posted February 26, 2015 I've been told not to run hot water threw the unit, just to keep the unit in an ambient warmer area. Quote Link to comment Share on other sites More sharing options...
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