Any difference in the 50/75/100 gpd units?

[bfoleyiii]

Is there any difference in the units on how well they will perform under a certain pressure range or do they all perform about the same (rejection wise) under the same pressure.

I just adjusted my PRV to get as high as I could and sit at about 53 or 54 psi and thought I'd ask if any one unit would perform better than the others with my home.

Thanks,

Bob

[Big_Pun]

ok from what i know and from expierence the 75 and 150 have the same rejection rate which helps in the life of your di resin, the 100gpg which i just replaced works fast but has a lower rejectioin rate and burns/uses up di resin faster, also when you go up to the 100-150gpd i believe 60-65psi of pressure is needed to run these correctly. when you say units do you mean the ro membranes?

[Europhyllia]

I would think a 99% rejection rate would be easier on the di resin than a 95% rejections rate since whatever passes through the membrane is going to go through the resin, no?

[Big_Pun]

I would think a 99% rejection rate would be easier on the di resin than a 95% rejections rate since whatever passes through the membrane is going to go through the resin, no?

your right, there are a couple membranes that have 99% rejection rates like spectrapure

[bfoleyiii]

As I understand the process the pressure only has an effect on the DI portion of the process. The DI membrane seems to be the limiting factor and is the step that is rated (50/75/100 gpd). So as I look at purchasing a unit the varialbles I need to consider are 1) Price--this is actually minimal difference on the units I am looking so not a big deal, 2) Production--it is going to be used for a 90g setup so again I'm not looking at needed to reach even the low end 50gpd on a regular basis, 3) Filter Replacement--I'm guessing it is going to be roughly the same for all units, maybe slightly better on the larger gpd units but I doubt I would actually see a difference, and 4) Usable RO/DI water/Waste water production--While I doubt going from a 1/4 to a 1/3 change will have that big a difference on the water bill it certainly would make my wife happy and that has to be incorporated in this project. I'm thinking I will set the unit in the laundry room and feed some of the waste into the washer but I dont like doing laundry enough to push 400g of water through it a day ;) so if one of the units will produce a better ratio of usable/waste for me that is important.

Hope that cleared it up a bit, but I have been going 55 hours on 4 hours sleep so it may not help.

[Big_Pun]

pressure effect the ro/membrane not the di resin(last stage) without proper pressure the ro/membrane will not function properly. so with out the right pressure you will not get the rated rejection rate. with 50-54psi i would go with the 75gpd. at my house i get 65psi so i can use the 150gpd without the use of a booster pump.

[bfoleyiii]

So I understand, the waste water is going to occur befor the last stage of the process?

[Big_Pun]

the ro membrane has a two outlets one is waste one is filtered water, you plumb the waste line to drain, filter water still has some stuff in it so you run that into di resin to remove the rest. im not sure if you know but the filter doesnt use all the water you put into it.

[bfoleyiii]

Yeah, and that is what I was trying to figure out. If one of the units will put out less waste than the others for my pressure.

[BuckeyeHydro]

Is there any difference in the units on how well they will perform under a certain pressure range or do they all perform about the same (rejection wise) under the same pressure.

I just adjusted my PRV to get as high as I could and sit at about 53 or 54 psi and thought I'd ask if any one unit would perform better than the others with my home.

Thanks,

Bob
The difference is in the membranes. I think this is the info re factory specs you are looking for:

50 gpd: 98% rejection, 50 psi, 77 F
75 gpd: 98% rejection, 50 psi, 77 F
100 gpd: 90% rejection, 50 psi, 77 F
75 gpd: 98% rejection, 65 psi, 77 F


Russ

[BuckeyeHydro]

If an RO system is configured properly and has factory spec conditions, they will all have about a 4 to 1 ratio of waste water to purified water, regardless of the membrane gpd rating.

Russ

[Big_Pun]

If an RO system is configured properly and has factory spec conditions, they will all have about a 4 to 1 ratio of waste water to purified water, regardless of the membrane gpd rating.

Russ

didn't mean to over step you Russ. I didn't even notice this was your forum. thanks for your help

[bfoleyiii]

Thanks for the help on this folks.

[BuckeyeHydro]

No worries...