Ro/di

[hoaglanddiver]

Wondering if anyone has some info on how many TDSs a DI will take out... Currently I have an RO system (25gpd) for my drinking water. I'm on a well. Raw water is around 280 TDS, after softening (which I hear is what you want to use in RO), it goes up to about 390/400. After RO, I'm down around 40. Will an add-on DI get rid of that last 40? OR do I need to invest in a better RO as well?
Thx,
Lee

 

[Gondore]

I'm not an expert on RO systems by any stretch of the imagination, but I would say you need a better RO unit.

 

[mojo~]

The main reason for adding a softener for any ro unit would be to get rid of the chlorine. The chlorine in the water will ruin the RO membrane. if its a new unit may ave to run it a bit to get it down. Make sure when you test you keep rinsing you glass with ro water as it picks up anything from your glass. The DI will take more out Should bring it to 0 it not going to hurt your tank if you read a couple tds. Mine without a DI runs around 3 or 4.

 

[Gondore]

I know that my water comes out about 3-4 tds from my RO before it goes through my DI which brings it to 0.

 

[hoaglanddiver]

Thx for all the replies. I'm on well water and it is very hard (28 gpg). all the literature I've read says to use softened water for the input into an RO system... due to the sodium ions, soft water tends to have more TDS. (as stated, in my case they are around 400 after softening). I wonder if a normal RO system can only get 400+ TDS down to 40.. OR can most get you close to 0. If that's the case, I def need to find a good brand. Any suggestions? My other research has stated the a membrane made of TFC is superior to a CTA membrane due to higher rejection rate.
(just FYI to those looking for RO systems)

 

[hoaglanddiver]

p.s. I do not have a sediment filter in my plumbing... do you think that would lower my TDS?

 

[Gondore]

I would check out The Filter Guys (http://www.thefilterguys.biz/). They are very helpful and their prices are reasonable.

 

[gwenvet]

I just bought an RO/DI system from the filter guys in Jan and it takes my 480tds PRE softened city water down to 0-1 before even going thru the DI. One thing I would suggest is to have your water tested for high levels of things that will use up a DI within 100 gallons. I forget what he said I must have in our city water but they make it totally impractical to use my DI because I would be replacing the filter every month! Would have liked to have known to check for that first before I wasted my money on the DI part but otherwise their service was fabulous.

 

[hoaglanddiver]

gwenvet. Good to hear.. can you tell me what model you bought and how happy you are w/ it? What about availability of replacement membranes and associated costs (easy to find - reasonably priced?)

 

[LornaS]

Lee, I am on a well and run a 3 stage ro filter that filters it down to about 8 then the di reduces it to zero. I run 3 filters in the array that are 10,5 and 1 micron then the ro then the di. This system is rated at 75g per day but due to weak pressure I don't get that high a rating.

here is the site I used and these guys offer sensational customer service......

http://www.airwaterice.com/product/1COMPACT/Compact_75_GPD_Reefkeeper_RODI.html

I got the refillable di filter and change out my own resin as it is much cheaper that way. Bulk Reef Supply sells the di filter medium

 

[gwenvet]

I have the $199 one on this page http://www.thefilterguys.biz/ro_di_systems.htm
I believe they have their own replacement filters and maybe even bulk that you can buy but I haven't had to replace any yet...I'm coming up on 6 mo this summer. I still can't figure out why the fish tank RO/DI systems are sooooo much less than the ones that places like Culligan sell for drinking water....they look they same to me!

 

[Buckeye Hydro]

Re: Ro/di

<a href=showthread.php?s=&postid=14752157#post14752157 target=_blank>Originally posted</a> by hoaglanddiver
Wondering if anyone has some info on how many TDSs a DI will take out... Currently I have an RO system (25gpd) for my drinking water. I'm on a well. Raw water is around 280 TDS, after softening (which I hear is what you want to use in RO), it goes up to about 390/400. After RO, I'm down around 40. Will an add-on DI get rid of that last 40? OR do I need to invest in a better RO as well?
Thx,
Lee

The TDS in your RO water should be a certain percentage of your feedwater TDS. In your situation, thats about 93% or more. So 93% reduction of 280 = 20 ppm
93% reduction of 400 = 28 ppm.

So it sounds like your RO membrane isn't doing what it should, or there is a problem with the way you are measuring the tds.

How old is your membrane?
What is the pressure on your RO system gauge when the system is running? Low pressure is not an uncommon problem on residential well systems. Low pressure can cause low membrane performance.

 

[Buckeye Hydro]

<a href=showthread.php?s=&postid=14752882#post14752882 target=_blank>Originally posted</a> by mojo~
The main reason for adding a softener for any ro unit would be to get rid of the chlorine.

The primary purpose of a softener is to remove hardness (primarily calcium and magnesium). This is well water so you would not expect to see chlorine in the water.

Russ

 

[Buckeye Hydro]

<a href=showthread.php?s=&postid=14753292#post14753292 target=_blank>Originally posted</a> by hoaglanddiver
I'm on well water and it is very hard (28 gpg). all the literature I've read says to use softened water for the input into an RO system

Yes - provide softened water to the RO system. The TDS of your well water is probably nearly identical to the TDS of your softener water. Remember the softener is nothing but a tank of cation DI resin - it exchanges Na for Ca and Mg.

Russ

 

[Buckeye Hydro]

<a href=showthread.php?s=&postid=14753301#post14753301 target=_blank>Originally posted</a> by hoaglanddiver
p.s. I do not have a sediment filter in my plumbing... do you think that would lower my TDS?

No sir. Sediment filters remove UNdissolved solids - sand/silt/clay. They have no effect on TDS (total dissolved solids).

However, its not unusual for well water to have heavy sediment loads, so whole house sediment filter is not uncommon in houses with well water.

Russ

 

[Buckeye Hydro]

<a href=showthread.php?s=&postid=14760413#post14760413 target=_blank>Originally posted</a> by gwenvet
I still can't figure out why the fish tank RO/DI systems are sooooo much less than the ones that places like Culligan sell for drinking water....they look they same to me!

The systems configured for this hobby use more expensive parts than the drinking water systems (except for the fact drinking water systems include some parts like pressure tanks not typically found on reef systems).

The big name places like the company you refer to have huge profit margins compared to the paper thin margins you've become accustomed to from the vendors serving this hobby.

Russ

 

[LornaS]

Thank you Russ for your knowledgeable input. Does your company sell booster pumps which will no doubt increase performance of the system on a low pressure home well system? I know that my system is low on pressure and therefore my system is not operating at top efficiency. Sorry Lee not meaning to hijack your thread but this may help you also

 

[Buckeye Hydro]

You bet. And not at all doing a sales job on you...

The booster pumps make an incredible difference, especially if you are used to something down around 40 psi.

For instance:
75 gpd membrane at 60 degrees and 40 psi = 41 gpd
75 gpd membrane at 60 degrees and 90 psi = 104 gpd

Russ

 

[gwenvet]

Thanks for the great knowledge base Russ. So as not to hijack this thread I'm going to post a thread about home filtration systems in the RC Lighting, Filtration and Other Equipment forum.

Actually it looks like it's being discussed there already. Ha.

 

[hoaglanddiver]

Thx for all the information... I will take all into consideration and I, too, will head over to the RC Lighting, filtration and other equip forum. Someone wanted to know my pressure... pump kicks on at 40 and off at 60. Not too awfully bad. I will most likely look at a system w/ a booster pump (if I can't get mine to work correctly -- I will be ordering new TDS meter this wk).