100gpd membrane ?

[E-A-G-L-E-S]

i know the rejection rate is only 90% and my TDS is 150-200 going in and only "4" coming out. I have sediment-carbon-membrane-di.......if i added another DI, would that get me to 0-1 TDS??

 

[BeanAnimal]

Short answer is YES, the second DI will take care of the rest if the TDS.

Long answer. You likely have "other problems", as the first DI should take the water to 0 TDS if it is working properly. It is either starting to wear out, or it is a horizontal cartridge and the water is bypassing some of the resin either by going over top of it (due to settling) or by channeling through it (due to it being packed to loosely).

Horizontal resin chambers are useless really. A vertical cartridge is much batter at forcing the water through all of the resin, and letting gravity help prevent channeling and bypassing.

You would be better off using a 75 GDP membrane, as the savings will add up quickly. This may mean changing the flow regulator on your unit (a few more bucks). Turning hte horizontal cartridge verical "may help" but it still is not the same as a true vertical cartridge.

Bean

 

[E-A-G-L-E-S]

its a brand new mixed bed DI....the membrane /sediment/carbon have about 200-250 gallons processed so far(so pretty new)???

i will buy a dow filmtec 75gpd membrane when this is exhausted from airwaterice.......if my psi on incoming water is low(30-40)...that would mean i wouldn't have to change the regulator, right?(i get about 45gpd from this unit(cold/slow well water)???

 

[BeanAnimal]

It sounds like the RO water is bypassing some of the RESIN then. However with 200 TDS input water, your resin is processing water that is around 20 TDS.

I get about 98% rejection at 50 PSI with my 75GPD membrane. My tap water is 235 TDS and my resin is being fed 2-4 TDS water (just checked), so will last at worst 5 times longer than yours and in reality I will likely get closer to 6 or 8 times the life out of it. So you see that adding a second DI cansister is not really the answer, as the first will be used up quickly, and your second will last as long as mine that is used in conjunction with the better membrane.

I am not sure what answer you are looking for....

What is your RO only TDS?


I am not the guy to calculate membrane or resin life with regards to rejection and TDS (others here can do that for you).

 

[E-A-G-L-E-S]

RO - 15 TDS

so you're saying getting the new membrane now is my best overall move?

thanks - matt

 

[BeanAnimal]

Matt it will help, as then you will be putting a lot lower TDS into the DI. You may also want to toss around the idea of adding a vertical DI housing. 20 TDS is not that bad, but you can see where the simple reality is with regards to the DI life.

As my 98% membrane wears, it will begin to pass more TDS, as will your 90% membrane. On the other side, the 90% membrane may not fail as quickly simple because of it's construction.

In any case the 75GPP membrane will give you better output water and less waste water at the pressure you are running.

You may want ot call AWI (or another vendor such as Buckeye) and explain your situation. Either vendor will give you an honest answer as to your most cost effective upgrade path.

 

[E-A-G-L-E-S]

the DI is vertical, along with sediment and carbon

will they help me considering my unit isn't from them, although i would be buying a membrane from them?

 

[BeanAnimal]

I think either company I mentioned will help you. So your DI is vertical? Is it color changing (not that this is a good inidcator), is it tightly packed or can you see where it has settled (assuming it is in a clear canister). Is the DI a full size canaister, just like your GAC and SED?

Bean

 

[E-A-G-L-E-S]

same size - yes it is vertical - color changing but in a white cannister - i have put about 20 gallons through it since i installed it yesterday...so it cannot be exhausted, not even partially?

i think a higher rejection rate membrane would help

 

[golfish]

I'm with bean, you'd be better off replacing the membrane for a 75 gpd unit.

FWIW, I still use two DI's on my Spectrapure unit.

 

[E-A-G-L-E-S]

so i should really just get both....i'll have to get the membrane, di mixed be, cartridge, cannister and plumbing pieces

 

[szwab]

I believe you need to run some ater through the DI before it will put out 0 TDS maybe around 40 or so gallons.

someone correct me if I'm wrong.

 

[E-A-G-L-E-S]

well it atarted at 15 and it went down to what its at now (4tds) after about 30g.....so i'll see if it goes down more......that would be nice