edress714 March 23, 2015 Share March 23, 2015 Quick easy question. Is the membrane the part of the system that determines the gpd? I currently have just a 50gpd on mine. All I would have to do is get a 150gpd membrane to speed up the process right? And 2nd question is, how do you guy minimize the waste water? Can you connect a 2nd membrane that connects to the first membrane dirty water output? TIA! Link to comment Share on other sites More sharing options...
khh27 March 23, 2015 Share March 23, 2015 (edited) You can change out your existing membrane or add one Usually you use the same gpd you already have so you that would make it 100gpd. I've never heard of someone adding a 100gpd to a 50gpd but I'm sure it doesn't matter...idk.. also adding the 2nd unit the incoming water on 2nd unit uses waste water from 1st unit this making it more efficient and cuts down on waste water output. But you need to make sure you have plenty of pressure to feed the extra gpd requirements. Usually 65psi incoming pressure is a baseline for any units producing over 75gpd. If you just change out membrane I don't think it has same effect on waste water as adding the 2nd. Usually if you have well water 65psi isn't achievable except with a booster pump. Edited March 23, 2015 by khh27 Link to comment Share on other sites More sharing options...
zygote2k March 23, 2015 Share March 23, 2015 don't forget to match the flow restrictor to the membrane.... Link to comment Share on other sites More sharing options...
fishgate March 24, 2015 Share March 24, 2015 You can just add the new membrane. Mine has the flow restrictor builtin check to see if yours does also and if so what it is rated for (if not then you need to replace it with the higher rated one). Mine is coralife. I went from 50 to 75 with no change in anything. If you redirect your waste to a second membrane you will wear that one out in a hurry using waste water. The wastage is not really that much. Certainly not as much as you will spend on an entire new membrane setup not to mention a pump since your waste pressure is too low to be of any use. Link to comment Share on other sites More sharing options...
Origami March 24, 2015 Share March 24, 2015 don't forget to match the flow restrictor to the membrane.... +1. Flow restrictors are matched to the membrane for best performance. If you change out the membrane, be sure to check what flow restrictor is recommended and swap out your current restrictor for the recommended one. Link to comment Share on other sites More sharing options...
wangspeed March 24, 2015 Share March 24, 2015 Watch the bulk reef supply YT videos about RODI. They are very educational on the topic. -- Warren Link to comment Share on other sites More sharing options...
edress714 March 24, 2015 Author Share March 24, 2015 Thanks everyone. I had a flow restrictor built in but it was clogged up so I bought a quick connect flow restrictor http://www.amazon.com/GPD-Flow-Restrictor-Quick-Connect/dp/B004BB9APK/ref=sr_1_2?ie=UTF8&qid=1427203478&sr=8-2&keywords=flow+restrictor So best thing for me to do is get another 50gpd membrane and connect that to the other making it 100gpd. or since connecting it to the waste water isn't recommended then maybe just sell my 50gpd one and get just one 100gpd? Link to comment Share on other sites More sharing options...
Origami March 24, 2015 Share March 24, 2015 The cheapest option over the long haul is to get the higher capacity membrane and the matching flow restrictor and replace both on your current system. This way, you're not faced with having to replace two membranes at a time in the future. Link to comment Share on other sites More sharing options...
khh27 March 24, 2015 Share March 24, 2015 The waste water is how you feed the 2nd unit. It is no dirtier than the water entering the first membrane it is just the water that has to be discarded in order to produce the quality water. Link to comment Share on other sites More sharing options...
tom39 March 24, 2015 Share March 24, 2015 IMO piggybacking a RO to increase the volume of water made and is a great option. Not trying to discredit what others have said but with proper flushing of the RO membrane and the use of a quality carbon block to remove chlorine and chloramines. The lifespan reduction of the RO membrane is unrecognizable. I have been running a piggyback setup for over a year with an average usage of 40g/week using 2 - 100gpd membranes and the tds output reading of both are 1-2tds depending on the time of day. Link to comment Share on other sites More sharing options...
Origami March 24, 2015 Share March 24, 2015 In normal operation, the lifespan of an RO membrane is about 3-5 years. Expect membrane costs to run anywhere from $25-$40 each in that time period. A new flow restrictor costs you under $10 typically and does not need to be replaced. Since you'd have to buy a new membrane in either case, the extra cost of upgrading to a larger membrane is the cost of the new flow restrictor. Thus, the cost recovery period for just upgrading your membrane is probably on the order of a year. After that, you're saving money by avoiding the additional maintenance cost on the second membrane. Note that I'm not factoring in waste water cost or DI resin depletion costs. Link to comment Share on other sites More sharing options...
edress714 March 26, 2015 Author Share March 26, 2015 Thanks everyone for the comments. Right now I have the 3 part filter going to the first membrane which I found out is 75gpd And then that goes to the DI resin. So I would get another 75gpd plus the kit and connect that so the flow goes first membrane to 2nd membrane to DI? right? Once this is done I would need a 150gpd flow restrictor? And that connects to the waste water line? Thanks again everyone Link to comment Share on other sites More sharing options...
khh27 March 26, 2015 Share March 26, 2015 (edited) Look at BRS video page they have a excellent video on how to install a add on membrane on there kits at least VERY good at explaining. Also they have a video on the flow restrictors. On my BRS 75g unit I didn't have to change it when I added the 2nd 75g unit but I think the one they use on their 75g unit is one that has a wide range of flow but check it out thye do a good job on explaining what restriction # do what GPH I think the 550 is what comes on the BRS. Edited March 26, 2015 by khh27 Link to comment Share on other sites More sharing options...
tom39 March 27, 2015 Share March 27, 2015 You only have to change out the flow restrictor if you are hooking up the RO membranes in parallel. (This would be where each membrane gets it's own feed and has its own discharge.) If you are looking to increase your product water output and reduce your waste water, (and what I believe you are thinking of doing) you would install the flow restrictor at the waste water output of the last membrane. Each membrane must be like in size and the size of the restrictor is matched to the size of the membranes. So if you are using 2 - 75gpd membranes, you would need 1 75gd restrictor. HIH Link to comment Share on other sites More sharing options...
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