New or Used RODI system? Which would u buy

cromag27 · Dec 5, 2018

theMeat said:
There’s no magic, or magic bullet. If you decrease the waste water with a smaller flow restrictor you also decrease membrane lifespan. Most recommend you shot for 4 to 1, unless saving water is more important than saving membrane.
If you use a second membrane run in series, then the waste water from the first membrane feeds the second, so your waste goes way down. But that comes at the cost of needing more psi, and a more complicated system.

and sending concentrated brine to the second membrane. sounds like more waste to me.

MartinWaite · Dec 5, 2018

cromag27 said:
by your own admission it doesn’t decrease waste. it merely passes it to the second membrane. so that’s great, burn through membranes faster! again, a correctly sized capillary flow restrictor is really going to dictate waste ratio, within limits.[/QUOTE

Where does what I say increase waste? If you take the waste from one membrane then put that waste through the second membrane you will reduce the total amount of water that is wasted, as I've already said go and watch the BRS YouTube video and educate yourself.

theMeat · Dec 5, 2018

@cromag27
Maybe the part you’re missing is the 2 membranes are not run parallel, but in series. So the waste water from the first goes through the second to become product, minus the second membrane’s waste.

Without getting confused about terminology, what is widely recommended, standard, whatever, it is 4 to 1 waste to product ratio for any given one membrane, even if that one membrane is in a 2 membrane system. Even almighty spectrapure recommends this 4 to 1 ratio as a standard

cromag27 · Dec 5, 2018

theMeat said:
@cromag27
Maybe the part you’re missing is the 2 membranes are not run parallel, but in series. So the waste water from the first goes through the second to become product, minus the second membrane’s waste.

Without getting confused about terminology, what is widely recommended, standard, whatever, it is 4 to 1 waste to product ratio for any given one membrane, even if that one membrane is in a 2 membrane system. Even almighty spectrapure recommends this 4 to 1 ratio as a standard

oh no i get it. trust me i get it. i have owned/assembled/fixed/tested many multi membrane systems, including commercial units. adding a second membrane to reduce waste doesn’t make sense at all. you’ll burn through membranes faster because of what you just said - you’re sending the waste from the first membrane, to the second. specifically, you’re not removing it just transferring it. a second membrane is great if you have to make more water. that’s it. but it will come with adverse effects.

the recommended waste ratio is 3:1 to 4:1 for most systems. the high efficiency, low waste units are specifically designed for this type of function and considered different animals.

cromag27 · Dec 5, 2018

MartinWaite said:
Where does what I say increase waste? If you take the waste from one membrane then put that waste through the second membrane you will reduce the total amount of water that is wasted, as I've already said go and watch the BRS YouTube video and educate yourself.

hmmmm...... brs is great for buying fancy lights and such. they aren’t a water purification company. they haven’t been selling rodi equipment for 30 years. they don’t have lab equipment and stringently test their filters. they don’t consistently innovate and improve on the technology they first created. no thanks, i won’t learn any from brs. lol.

MartinWaite · Dec 5, 2018

cromag27 said:
hmmmm...... brs is great for buying fancy lights and such. they aren’t a water purification company. they haven’t been selling rodi equipment for 30 years. they don’t have lab equipment and stringently test their filters. they don’t consistently innovate and improve on the technology they first created. no thanks, i won’t learn any from brs. lol.

There you go you won't learn from nobody because you're always right!
So my water coming from my tap is 80TDS I put it through my first membrane and the waste goes up to approx 100 TDS that dirty water goes through the second membrane and I still get nearly the same amount of clean water from the second membrane as I did the first membrane so I've 2 lots of clean water from the amount that went through the pre filters and carbon filters so where have I increased my waste water I have reduced it by approximately 20% because I got 20% more good water. Do you understand that and by the way my friend who lives the other side of the city to me, I'd better tell him not to use his RO filter anymore as his dirty water from his tap is nearly 400 TDS and he'll blow through twice as many membranes as I will even although I use 2 at a time! Some people will never learn. LOL

Ready4Launch · Dec 5, 2018

As a newb to RODI systems, with current technologies and setups, if I filtered 100 gallons of water, how much waste could be my least amount?

Buckeye Hydro · Dec 6, 2018

Flippers4pups said:
I agree with the above only if the new unit provides more canisters...

Think of a four stage RODI as the default configuration:
sediment->carbon->RO->DI
Add to that configuration only to address specific water quality issues or unique ways you want to use the system.

Avoid the trap of thinking "more filters = better filtration." We often see first time buyers go for the cobbled together systems on ebay because they have 8 stages of some such craziness.

Russ

Buckeye Hydro · Dec 6, 2018

Super Fly said:
it's too small (50gpd) that I was using with previous tank prior to upgrading tank. Besides, even with higher capacity gpd, this brand has too high waste-to-clean-water ratio (5-1)... would like to waste less water and save $ on water bill too.

YOU control that ratio - you can make it anything you want by swapping out a little $4 plastic piece called a flow restrictor.
https://www.buckeyehydro.com/capillary-flow-restrictors/

Russ

Buckeye Hydro · Dec 6, 2018

Super Fly said:
yes. Aquatic Life RO Buddie 50 gpd w DI resin and the smart booster pump.

I would drop that system like a hot potato!

Buckeye Hydro · Dec 6, 2018

Flippers4pups said:
Well thats a tough one. By the time you bought the new cartridges for the Spectrapure, you would be pushing $200. A new 4 stage BRS unit runs around $150. The only thing is it's lacking TDS meter and pressure gauge. Those could be added later. The new BRS unit comes with all the cartridges, shipped free.

$200??? You might want to check into shopping for replacement filters of equal quality at another vendor.

Buckeye Hydro · Dec 6, 2018

Flippers4pups said:
Should be on the incoming line to the unit from the house water line. That would tell you how much pressure is going to the unit.

If you are only going to have a single gauge, you'd place it AFTER all the prefilters (sediment and carbon) but before the membrane. Or into the membrane housing port if you have one. You want the gauge to see the same pressure the membrane sees.

Russ

Buckeye Hydro · Dec 6, 2018

theMeat said:
FWIW, IMO, ime, you need good water pressure for anything over 75gpd. So if not, get a booster pump

You need adequate pressure regardless of the gpd rating of the membrane. The key is to understand the factory spec pressure on the membrane you have. If you provide lower pressure, performance will suffer.

Russ

Flippers4pups · Dec 6, 2018

Buckeye Hydro said:
Think of a four stage RODI as the default configuration:
sediment->carbon->RO->DI
Add to that configuration only to address specific water quality issues or unique ways you want to use the system.

Avoid the trap of thinking "more filters = better filtration." We often see first time buyers go for the cobbled together systems on ebay because they have 8 stages of some such craziness.

Russ

As you may know, many local water supply companies use chloramine as a disinfectant. Having a pre sediment filter, 2 carbon blocks and a DI chamber will give the best removal rates. Single carbon block may exhaust more quickly than one with 2 carbon blocks.

Buckeye Hydro · Dec 6, 2018

Right on - maybe a third of water utilities have made the switch to chloramines. That's a good example of a specific water contaminant that might require an additional filter.
https://www.buckeyehydro.com/chloramine-special-rodi/
https://www.buckeyehydro.com/chloraguard-chloramine-carbon-block/

Russ

Super Fly · Dec 6, 2018

Buckeye Hydro said:
I would drop that system like a hot potato!

LOL!

Buckeye Hydro said:
If you are only going to have a single gauge, you'd place it AFTER all the prefilters (sediment and carbon) but before the membrane. Or into the membrane housing port if you have one. You want the gauge to see the same pressure the membrane sees.

Russ

ok, that's what others said online as well. Thanks! BTW, what is "Buckeye Hydro" is that a RODI company?

theMeat · Dec 6, 2018

Buckeye Hydro said:
You need adequate pressure regardless of the gpd rating of the membrane. The key is to understand the factory spec pressure on the membrane you have. If you provide lower pressure, performance will suffer.

Russ

Can’t argue with that. That’s good advice.
While manufacturers rate their membranes between let’s say 40 and 90 psi. The bigger more gpd the membrane, the bigger more water on flow restrictor as well, the more water needed to go in. Another words the bigger the gpd the bigger the loss in efficiency is effected by lower psi. Look at first pic, loss on bigger membrane is greater

Buckeye Hydro · Dec 6, 2018

Fun fact to know and tell: There is no such thing as a 90 gpd membrane - it is just a relabeled 75 gpd membrane where the vendor tells you to run it at 10 psi more than the factory spec. Go figure. People seem to eat it up... without knowing it is just marketing spin.