RO+DI : 50 GPD vs 100 GPD ?

[dtran01]

I live in an apartment and dont want to mess with plumbing but buying water from the LFS is getting too pricey.

I found these portable RO/DI filtration systems on ebay and was wondering what the differences are between the following:

50 GPD
http://cgi.ebay.com/0PPM-Portable-50GPD-Reverse-Osmosis-RO-DI-Water-Filter-/110588516909?pt=LH_DefaultDomain_0&hash=item19bf96da2d

100GPD
http://cgi.ebay.com/0PPM-Portable-Reverse-Osmosis-RO-DI-Water-Filter-3Pcs-/110581413778?pt=Small_Kitchen_Appliances_US&hash=item19bf2a7792

Are the only differences between the two how much water it can produce? is there a quality decrease in doubling the rate the amount of water produced?

[jubelale]

Generally the more GPD the less TDS removed.

[dtran01]

so the 50 gpd is cheaper and better?

[dtran01]

This seems to be a 6-stage portable RO/DI instead of 4stage in previous links:
http://cgi.ebay.com/Flexible-100-GPD-Reef-Drinking-6-stage-RO-Filter-System-/110557195331?pt=Small_Kitchen_Appliances_US&hash=item19bdb8ec43

I'd really appreciate it if someone could help me figure out if the extra two stages makes any difference. They're both marketed as 0 ppm ??

[Paco]

One thing I will tell you is that the horizontal DI canisters are almost useless. Yes, they will work OK when you first hook them up but once you have put some gallons thru the DI resins, they will begin to shrink, and soon you will be bypassing the resins meaning that you are producing impure water.

There's not a ton of plumbing related to connecting an RO system -- yes, you can tie it to your drain line directly but you don't have to. Maybe you want to check w/BRS and get something rather than eBay.

[dtran01]

why cant i mount it vertically?

[bmkj02]

I never heard the more gph the less tds. My unit is a 175gph and its still at 0 tds. Not saying I disagree just that I never heard of that.
Here is your problem with the horizontal units. Other than the membrane if the other stages are horizontal the water tends to ride on the top of the stage and bypass whatever its going through whether its the carbon or DI. A vertical unit makes sure the water is pushed through the whole media and not bypassed giving you the 0 tds you are looking for.
Usually the 5 stages are standard. Its a sediment filter plus 2 carbon filters then the membrane and last the DI unit. This set up is giving you an extra carbon which really you can do without. Its price is cheap for these reason. Check out Bulk Reef Supply for a 5 stage unit. It cost a little more but the quality is well worth it

[bmkj02]

why cant i mount it vertically?

I guess you can. Never really thought of it that way. I just have heard nothing but bad things about these units.

[scubasteve06]

I built my own RO/DI unit from BRS. I got everything I wanted at 150 gpd and all the little accesories that only came with the much more expensive deluxe kits for 206 bucks before shipping. Their 75 gpd deluxe kit was 230 bucks I think, I just didn't want to pay for the dual DI resin.

[EdMan71]

Check with BRS. A 50 gal is all you need unless you have a large tank and use alot of water for water changes and top off water.

[scubasteve06]

Edman I think the smallest RO/DI unit BRS has is a 75GPD system IIRC.

[Soymilk]

I would recommend doing a little bit more reading on ro/di systems. I also live in an apt and it only took me about 10 mins to set mines up. Find out what the tds and water pressure is first. If you have pretty low tds you could get away with a cheaper system.

Not all sediment filters are the same, not all ro membranes are the same. I would recommend buying a decent system from Brs,tfg, or bfs. They use quality prefilters and membranes.

Usually the higher gpd membranes require higher water pressure so make sure to do your homework. If you don't have enough waterpressure the membrane will not function correctly and let Alot of junk thru.

[aleonn]

+1 on BRS. Got a 5-stage PLUS that includes dual TDS meters, pressure gauge, and filter bypass for $180. I also upgraded to 150 gpd kit for $59 more. Works great, and is easy to use.

[dtran01]

from a google search they have been around for 4-5 years and any bad reviews seem to be isolated. they seem to have primarily good reviews.

I have a BRS dual reactor so I know that BRS sells quality product, but the 50GPD product is only 68 dollars and so the BRS product is 3 times as expensive.

i'll look into it -- i suppose it may be worth it in the long run..

[d0ughb0y]

I never heard the more gph the less tds. My unit is a 175gph and its still at 0 tds.

It's TDS at the RO membrane output.
The rejection rate of a 100 gph membrane is lower than a 50 gph membrane. 100gph will produce more clean water output with slightly higher Tds but at the same time the waste water output is less.

[newguy1233]

I got the economey 4 stage from BRS and love it, just the beefyness and the quality of construction alone is well worth it and it comes with all the fittings more or less that you might need. check them out

[thewire]

i am tempting to buy one of those unit from PWC but man i Heard bad stories about them......but they are very affordable....
I can't justify spending $200+++ for a RODI when I have only 12g tank...it will takes over 3 years to pay off considering 10% weekly waterchange and 3% top off

[aleonn]

Ya, for a 12g tank, I'd just buy RO or saltwater from the LFS.

[Engloid]

The system itself has little to do with the TDS, so I'd go cheap on the system, and then buy good brand name filters to go in it.

I have a 6 stage (two DI's), but don't even use the DI at all. They're just empty canisters. from what I have been told, the DI is something you may want to do for taste if you're drinking the water... but when I have had a few people do taste tests of my RO water vs the filtered water on the fridge, or bottled water, they always prefer the RO water.

[Paco]

From what I have been told, the DI is something you may want to do for taste if you're drinking the water...

Totally wrong. DI is the final stage of water purification -- it pulls the final remaining solids and contaminants out of the post-membrane water. No membrane can produce completely pure water -- they all have rejection rates from 90% to 97% or even 98%, but that last 2% is still there. And if that last 2% is phosphates, good luck ever controlling algae growth. If it's copper, you'll never have problems with ich :worried: but you also won't be able to grow corals. :thumbdown

It's a risk to not run DI. I'm not saying you can't do it or be successful without it but why take the risk? To save a few dollars a month? :hmm4:

[Engloid]

Totally wrong. DI is the final stage of water purification -- it pulls the final remaining solids and contaminants out of the post-membrane water. No membrane can produce completely pure water -- they all have rejection rates from 90% to 97% or even 98%, but that last 2% is still there. And if that last 2% is phosphates, good luck ever controlling algae growth. If it's copper, you'll never have problems with ich :worried: but you also won't be able to grow corals. :thumbdown

It's a risk to not run DI. I'm not saying you can't do it or be successful without it but why take the risk? To save a few dollars a month? :hmm4:
I find it hard to believe that you can get 100% removal of anything by running water over some particles one time. With the membrane, it is similar to a filter in that ALL particles must go through it. In the DI canisters, it's just particles of resin and molecules run past them. If the resin doesn't contact the particle, it can't absorb it. Likewise, I'm sure particles can sometimes contact it and not be absorbed.

I get down to 3ppm of TDS in my RO water, without using any DI resin. That's way better than even the 98% pure water you mention. 98% would be 20,000ppm. I actually found that water I put into a clean bowl measured 8ppm, but water straight out of the RO output line was 3ppm. We suspected that the bowl could have had some residue from the dishwasher, soap or something like that.


I'm not saying that it isn't going to be better than just using RO... but I don't use the DI and can't even get chaeto to grow in my sump. I would say that the majority of reefers do not use DI either.

[Paco]

I find it hard to believe that you can get 100% removal of anything by running water over some particles one time.

And I find it hard to believe that something made of aluminum, full of people and luggage, is able to fly thru the air at almost 600 miles per hour, and yet, I fly on planes ten or fifteen times a year.

I get down to 3ppm of TDS in my RO water, without using any DI resin. That's way better than even the 98% pure water you mention. 98% would be 20,000ppm.

Umm...what? Let's say you have tap water that's 200 PPM TDS -- 98% rejection of that gives you 4 PPM water. I'm not even sure what you're referring to, but clearly, you don't understand what you're talking about.

I would say that the majority of reefers do not use DI either.

And we should value your opinion because...?

[Engloid]

And I find it hard to believe that something made of aluminum, full of people and luggage, is able to fly thru the air at almost 600 miles per hour, and yet, I fly on planes ten or fifteen times a year.
I'm sorry such things are so hard for you to believe...but I promise you that it happens. :worried:


Umm...what? Let's say you have tap water that's 200 PPM TDS -- 98% rejection of that gives you 4 PPM water. I'm not even sure what you're referring to, but clearly, you don't understand what you're talking about.

Sorry to have been so complex that you couldn't comprehend it.


And we should value your opinion because...?
I think your attitude towards others tells me that your opinion isn't one I want to hear.

Maybe one day the rest of us will achieve the level of intellect you think you have. :rolleyes:

[dc]

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