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Discussion Starter · #1 ·
Just made the jump to a dual membrane setup and it comes with pluses.

First it will turn the usual 1g RO to 4g waste to 1 g RO to 1-1.5g waste.
Second I will be able to access upto 300 gpd with the new setup. :eek5:

My plan for water changes that I'm working on it a hang on overflow box from ESHOPPs that I will set in the tank and get the siphon going and drain water either outside to the grass or to a drain in the winter time. My RO unit is plumbed to the tank so all I will have to do is turn it on and let the water flow into the tank. In 12 hours I can for a nearly 100% water change without ever draining the tank.

Craig
 

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Discussion Starter · #3 ·
I'm using GE Merlin, it has 2x membrane also, 720 gpd. It's the only way I can WC my 220g tank in a decent time frame.
Yeah I've got my 150 and want to eventually go larger at some point. I've heard alot of good about those Merlins. I've got a The Filter Guyz system that is currently running 75 GPD. After some talking as I wanted more flow they are setting me up with the dual 150gpd membranes and booster pump so I can crank out hte RO for my tank.

Craig
 

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I like the GE Merlin a lot, I used it for 2 years for drinking, now moving it to fish tank duty.
It requires very high pressure though, my house has 70psi so it work fine, but when the sprinkler turns on dropping the pressure I can hear it struggle.

If you haven't purchase the 300gpd yet, why not give the Merlin a try? Look like you have already decided to use the booster pump so pressure shouldn't be a problem for you.
 

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Discussion Starter · #5 ·
I like the GE Merlin a lot, I used it for 2 years for drinking, now moving it to fish tank duty.
It requires very high pressure though, my house has 70psi so it work fine, but when the sprinkler turns on dropping the pressure I can hear it struggle.

If you haven't purchase the 300gpd yet, why not give the Merlin a try? Look like you have already decided to use the booster pump so pressure shouldn't be a problem for you.
I though about it but I already have all the parts as I already have their RO/ DI unit so I only needed the second membrane and the booster pump so not a whole lot of cost on my end for the upgrade.

Craig
 

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I though about it but I already have all the parts as I already have their RO/ DI unit so I only needed the second membrane and the booster pump so not a whole lot of cost on my end for the upgrade.

Craig
got it.

300 gpd is actually pretty good. I haven't compare Merlin performance, but I doubt it is as good as the normal RO/DI membrane.
 

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Discussion Starter · #7 ·
Would be curious what your water comes out at. I know my water from the main line comes in to the RO unit at 120-125 TDS comes out before the DI unit at 5 TDS and leaves the Di Unit at 0 TDS.

Will be great considering I can swap out 12.5 GPH on my 150g tank, should help reduce stress as the water level will never change and the water will mix in slow enough to help reduce stress in the tank.

Craig
 

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My plan for water changes that I'm working on it a hang on overflow box from ESHOPPs that I will set in the tank and get the siphon going and drain water either outside to the grass or to a drain in the winter time. My RO unit is plumbed to the tank so all I will have to do is turn it on and let the water flow into the tank. In 12 hours I can for a nearly 100% water change without ever draining the tank.

Craig

Are you sure this is what you want to do?

RO water is extremely soft, and might be too soft for the plants and fish you want to keep. I use RO/DI water for my planted tank, but I need to build GH and KH first. Considering that may people change 50% of their water a week, that would really cause a drop in GH and KH.
 

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Discussion Starter · #10 ·
Are you sure this is what you want to do?

RO water is extremely soft, and might be too soft for the plants and fish you want to keep. I use RO/DI water for my planted tank, but I need to build GH and KH first. Considering that may people change 50% of their water a week, that would really cause a drop in GH and KH.
I've used nothing but pure RO for a long time on my tanks. Also teh Altums I'm keeping coem from a PH of 5 with virtually no TDS and I have kept this tank aroun 5.5 and 50 or so TDS.
 

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We get this question a lot - I think we need to add this to our FAQ list: http://buckeyefieldsupply.com/FAQ.asp

We feel it is misleading to tell people they can cut down on waste water by adding a second membrane. Here's why.

First - remember that what folks call "waste water" really would be better thought of as "flush water" in that this water serves the important purpose of internally flushing the surface of the semipermeable membrane to keep the membrane from fouling/scaling.

When you configure a system with two membranes in series (the waste from the first membrane going to the "in" port on the second membrane), for this discussion let's say it's two 75 gpd membranes, the system behaves like you have a single long (75 gpd x 2) 150 gpd membrane.

Now - if you use a proper flow restrictor, that is, one for a 150 gpd membrane, you'll have about a 4:1 waste to product ratio. Sounds familiar, right?

If however you don't change the flow restrictor - meaning you keep using the same restrictor you were using when you just had one 75 gpd membrane, then you'll see a waste to product ratio much lower than 4:1. But remember that the recommendation for a ~4:1 ratio comes from the membrane manufacturer. They are telling you that you need about a 4:1 ratio to keep the membrane flushed and keep the membrane from fouling or building up scale. Run the system with a lower ratio and you will foul/scale the membrane(s) quicker than would have otherwise been the case.

Instead of adding a second membrane to lower that ratio, you could have just changed out your flow restrictor ($4) instead. A much less expensive approach to get you to the same endpoint in terms of saving on waste water.

Now, to confuse things just a bit. Filmtec specs call for the 4 to 1 ratio on the basis of assumptions about the water that will be supplied to the membrane. If you have very soft water you MAY be able to get a decent service life from the membrane running at a ratio lower than 4 to 1 (e.g., 3 to 1). Remember that the waste water from the first membrane is about 25% harder than your tap water.

Bottom line: If what you are after is reduced waste water, experiment with a different flow restrictor for $4 instead of messing around with a second membrane plumbed in series.

As a side note, you can also lower the ratio by increasing the pressure delivered to the membrane (with a booster pump), because flow restrictors are sized assuming you are providing factory spec conditions (50 psi and 77 degrees for Filmtec membranes). Increase the pressure and you'll drive more water through the membrane and viola - less waste water. But as I mentioned above, if you do this (just like over-restricting a membrane) - the lower the waste to product ratio, the shorter the lifespan on the membrane.

Makes sense?

Russ
 

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Discussion Starter · #15 ·
We get this question a lot - I think we need to add this to our FAQ list: http://buckeyefieldsupply.com/FAQ.asp

We feel it is misleading to tell people they can cut down on waste water by adding a second membrane. Here's why.

First - remember that what folks call "waste water" really would be better thought of as "flush water" in that this water serves the important purpose of internally flushing the surface of the semipermeable membrane to keep the membrane from fouling/scaling.

When you configure a system with two membranes in series (the waste from the first membrane going to the "in" port on the second membrane), for this discussion let's say it's two 75 gpd membranes, the system behaves like you have a single long (75 gpd x 2) 150 gpd membrane.

Now - if you use a proper flow restrictor, that is, one for a 150 gpd membrane, you'll have about a 4:1 waste to product ratio. Sounds familiar, right?

If however you don't change the flow restrictor - meaning you keep using the same restrictor you were using when you just had one 75 gpd membrane, then you'll see a waste to product ratio much lower than 4:1. But remember that the recommendation for a ~4:1 ratio comes from the membrane manufacturer. They are telling you that you need about a 4:1 ratio to keep the membrane flushed and keep the membrane from fouling or building up scale. Run the system with a lower ratio and you will foul/scale the membrane(s) quicker than would have otherwise been the case.

Instead of adding a second membrane to lower that ratio, you could have just changed out your flow restrictor ($4) instead. A much less expensive approach to get you to the same endpoint in terms of saving on waste water.

Now, to confuse things just a bit. Filmtec specs call for the 4 to 1 ratio on the basis of assumptions about the water that will be supplied to the membrane. If you have very soft water you MAY be able to get a decent service life from the membrane running at a ratio lower than 4 to 1 (e.g., 3 to 1). Remember that the waste water from the first membrane is about 25% harder than your tap water.

Bottom line: If what you are after is reduced waste water, experiment with a different flow restrictor for $4 instead of messing around with a second membrane plumbed in series.

As a side note, you can also lower the ratio by increasing the pressure delivered to the membrane (with a booster pump), because flow restrictors are sized assuming you are providing factory spec conditions (50 psi and 77 degrees for Filmtec membranes). Increase the pressure and you'll drive more water through the membrane and viola - less waste water. But as I mentioned above, if you do this (just like over-restricting a membrane) - the lower the waste to product ratio, the shorter the lifespan on the membrane.

Makes sense?

Russ
Mostly but I'm using two flow restrictors each one rated for the 150gpd on each membrane plus a booster pump to run about 80 PSI. The way a dual system is saving waste is to run it through the second membrane to salvage teh extra water out of it. Does it mean a shorter lifespan for the second membrane, probably but being as membranes aren't overly expensive if I had to replace one or both of them once a year it wouldn't be that expensive, about $100 a year to replace both of them.

Do you have other proof of what your saying is correct, like the science and math behind it? I've worked closely with thefilterguyz.biz on my system and they are a mainstay with high regards on the salt forums and don't tink they would be trying to steer anyone wrong. You have made several statements but I want to see your math and science behind them proving they are right.

Craig
 

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financial question on RO system.... I heard "waste"/"flushed" words... Yes I'm somewhat conservative to our fresh water system. So my question is, Is it cheaper to have your own RO system or buy at lfs 49cent each Gallon? Because from what I have read this system will "waste"/"flushed" the remaining water. For you guys, do you use the "waste"/"flushed" for shower, dish wash, laundry, sprinkle, toilet water? or you guys just drain them to sewer?
 
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