What kind of RO system do you run????

[Buckeye Hydro]

Jesus Walter, you expect me to follow that???? I suppose it makes sense, except for the part about having it before the reducing valve, whatever that is. I'm going to have to have mine off of a utility sink in the laundry room. It's the only place it's gonna work.

Can I buy an add on 2nd membrane and run it in line like yours or would I have to get a whole new additional set up?

We'd be happy to help you troubleshoot your system. Feel free to call in when you are in front of the system

Russ
513-312-2343

 

[Buckeye Hydro]

NO, not at all. Housings are housings, it's all in the filters & membrane you put in them.

We'll respectfully disagree. Having sampled many many brands of housings, they are not all the same.

I also run a dual membrane setup where the reject water from the first filter supplies the second membrane, so i'm getting about a 1-1.5/2 product to reject ratio.

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.

Bottomline: 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.

 

[captain7359]

We'll respectfully disagree. Having sampled many many brands of housings, they are not all the same.

Interesting. What have you found to be the differences? Are they bypassing waster around the filter or not sealing?

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?

But, you're still running 4:1 through each membrane, but getting twice the product water is what gets you to 2:1, correct?


To get less waste the flow restrictor swap makes sense as well, but what does that do to tds? I think tds is what scares most reefers, but at what level should we actually take concern at?

In the end each of us just have to decide whether they want a stock system run at factory specs which gives the rated flows and flush ratio, or if they want higher flows or lower flush ratios to save water, but at the cost of replacing the membrane sooner.

 

[pascal32]

Filterguys 75gpd here

TDS settles to 2-3 before DI after a few minutes.

Dual DI, I measure TDS out of the first DI, as soon as it hits one I move the second DI into the first location and repack the original and place it second.

I believe.hot water kills the membrane!

Try to flush the membrane once a month.

 

[Buckeye Hydro]

I believe.hot water kills the membrane!

Anything over 113 voids a filmtec warranty

 

[Buckeye Hydro]

COLOR]



But, you're still running 4:1 through each membrane, but getting twice the product water is what gets you to 2:1, correct?

Things we saw in varius brands:
Some sumps have male threads, and tend to crack.
Poorly casted lids
Poorly threaded lids (for the fittings).

Then go beyond the housings - big difference in the quality of fittings between manufacturer.

And then some systems have or don't have things like a flush valve, pressure gauge, thermometer.

We like aluminum brackets rather than steel for the small systems because it doesn't rust.

Etc, etc, etc

To get less waste the flow restrictor swap makes sense as well, but what does that do to tds? I think tds is what scares most reefers, but at what level should we actually take concern at?

Increasing the recovery (by choking off the waste line) will increase the pressure and decrease the tds. Until you scale the membrane.

In the end each of us just have to decide whether they want a stock system run at factory specs which gives the rated flows and flush ratio, or if they want higher flows or lower flush ratios to save water, but at the cost of replacing the membrane sooner.

Agreed. Good decision to make based upon understanding the need for/purpose of the 4:1.

Russ

 

[Gary Majchrzak]

enlightening thread.

It certainly has me looking at my RO unit in a different light.

 

[NirvanaFan]

I use a Water General 100gpd unit. The good to waste water ratio doesn't really matter to me. Water is cheap, and this unit works well for me.

 

[Gravesj1s]

Im just going to throw out here that if volume per day isn't an issue and your looking for effciency,then I'd go with the lowest gal/per/day you think is going to work for you.

With the lowest g/p/d units you may not even need di resin at all.IME.My first Ro unit I used was only 15 gal per day but had a tds reading of 0.

Same unit,replaced ro membrane to 24g/p/d filmtec membrane, swithed out flowrestrictor to match 4:1ratio. Tds 1-2 reading.After adding a Di cannister tds 0.

Same unit ,I replaced the Ro membrane again after 9 years of use with a spectrapure gauranteed factory tested 98.8 membrane but moved up to a 60g/p/d and matched flow restrictor 4:1 ratio.Tds 3-4 w/out di cannister.with (1)di it ran 1-2.So I added a second Di cannister,Tds reading 0-1.

Conclusion,seems like the product water solids get through the membrane more-so the higher the gpd the unit.Imo/e.

 

[450reef]

cully i love mine its a vertex puratek 100gpd unit and it seriously runs about a 1:1.5 ratio - tim got it for me - its not the cheapest thing but ya get what ya pay for any questions feel free to ask

 

[Newreeflady]

Couple questions:

1) How does one flush the membrane?

2) What is the flow restrictor doing? (Russ, couldn't find the description on your site, just the part.) How is this different from just closing the waste line part way?

I just changed all of my filters and am still getting seriously high waste water ratio. Can I add a restrictor to get down to 4:1 from say, perhaps, 6:1?

Thanks!
Angela

 

[Capt_Cully]

Well...after having given all this a second, careful read through, it really does make sense. The two variables that I forsee being the bigest pain in the butt, are pressure and temperature. I will likely add a second DI but not necessarily another membrane. Like I said, the most I ever make is 44 gallons (volume of a Rubbermaid Brute). I can add a pressure guage from BRS for under $20.

Realistically, I can't plumb in before the household pressure reduction valve. It's in an area that doesn't allow for waste water drainage or collection. No drain, no sink. I'm going to be forced to run it off of a utility sink in the laundry room.

For me, the waste to product ratio, is a concern, but less of a concern with regard to obtaining 0 TDS.

Questions:

if I tap into the plumbing BEFORE the tap, how do I get a good mix of hot and cold water to bring me to 65 or 75 degrees? Are their thermometers available?

If I change to a 75 GPD membrane, do I need to change the flow restrictor? I'm not really clear on the particular ratings that are made available.

The point of this thread was for me to be able to just say my RO sucks and go buy a better one. Thanks to the input of many, I see it is a clearly salvagable system with some tweaks. I have become enlightened as to the particular components, I otherwise had taken for granted. This has turned into an awesome thread!

 

[Gravesj1s]

Couple questions:

1) How does one flush the membrane?

2) What is the flow restrictor doing? (Russ, couldn't find the description on your site, just the part.) How is this different from just closing the waste line part way?

I just changed all of my filters and am still getting seriously high waste water ratio. Can I add a restrictor to get down to 4:1 from say, perhaps, 6:1?

Thanks!
Angela

Theres two types of flow restrictors get one that is adjustable with the attached thumb wheel,not the type where you have to cut the inside tubing.

Couple reasons why,the type you cut is more permenant so if you upgrade you may have to buy a knew one.Water temps vary season to season another reason to go with the thumbwheel type.FWIW -they cost the same ,like 5 bucks.The thumbwheel flow restrictor you wont have to replace if you ever decided to swith membranes,Just redial it in to 4:1.

 

[Newreeflady]

Theres two types of flow restrictors get one that is adjustable with the attached thumb wheel,not the type where you have to cut the inside tubing.

Couple reasons why,the type you cut is more permenant so if you upgrade you may have to buy a knew one.Water temps vary season to season another reason to go with the thumbwheel type.FWIW -they cost the same ,like 5 bucks.The thumbwheel flow restrictor you wont have to replace if you ever decided to swith membranes,Just redial it in to 4:1.

Ouf. I just placed an order for the cutting type from Prem. Aq. I would ask them to put the other, but it doesn't look like they carry any sort of thumbwheel type?? :/



Thanks!
angela

 

[Mr Reefer 1690]

I have a well and didn't want to stress over all of the waste water or deal with the expense of an RO system with the extra pressure pump. I live near Utica and bring city water home and siphon it thru a DI unit. I put the 5 gal bucket on a shelf and siphon the water thru a micron / carbon chamber and 2 DI chambers. This produces 0 TDS water with no waste at little cost.

 

[iamwrasseman]

i like that deal !Mark ,i saw your unit and it should be salvagable for sure as you just need new cartridges and yes maybe a gauge but i would not suggest that you try to mix hot and cold water as hot water gets a bit more pressure at very low flow and will overpower the cold water and then you will have a meltdown IMO.

 

[Gravesj1s]

~ Mark,just in case you haven't already found out.The thermometer Russ mentioned was just that a thermometer.I dont see how it would do any real good though for us NY'ers.The temp ratings should actually be rated on these units closer to 50F for a better average.Cant imagine theres many places in this country with 77F tapwater.

I dont know about anyone else here but I just see it as more of a hassle to get involved in raising the temp.The pressure on my unit has always ran around 55-70,in that range I have only noticed slightly less product water (i.e.-takes a little longer to fill the bucket in the coldest months)But never noticed any change in tds so I dont worry about it.

you might want to consider using nothing higher than .5 micron prefilters and a 10-20thousand gal chlorine guzzler carbon block.I just think the prefilters that come standard are inadequate for the water around here.I dont notice any pressure drop or any buildup on prefilters when I was using 1 micron prefilters.

Good luck with everything with what ever you decide.

 

[Gravesj1s]

1) How does one flush the membrane?

it just means backflush the membrane.Couple valves plumbed in to reverse the flow for a few minutes.Pretty easy diy or prefab you can buy.

When the unit runs and then shuts off the pressure across the membrane equalizes and allows tds to creep through,so when you turn it on again you might notice an increase in tds for a few minutes.Idealy,you would want to have a shutoff before the whole unit and manually shut it off,when turning it back on backflush the unit first for a minute or so everytime you make new water.

I just manually shut it off when not in use and ditch the first cup or so.I dont have a backflush.

 

[Capt_Cully]

So if I get it plumbed in line (vs a diverter on the faucet) so I have it hooked into the cold water supply line?

Thanks

 

[Gravesj1s]

Yeah I just tap the cold supply line.As for getting the right temp I dont see how it could be done without alot of effort and ,well, Iguess not convinced it is really going to make that much difference.If it was pressure then I would be more concerned.Just my thought.