R/O

[Sarracenia0]

Hello Guys,
    I have always used rainwater for my CPs, but this is going to have to change.  I am now using almost 5 gallons a day and I just don't have the time any more to fill up milk gallons.  I have been thinking about getting a R/O filter, but I have a few questions.  

-Can R/O Filters be hooked up to a garden hose?
-Can R/O Filters pump there own water out of a trash can or   something?
-What size R/O filter would I need to supply my needs of 3-5 gallons a day?

Can any of you guys recommend some R/O Filters?

Any help would be greatly appreciated!

Mike

 

[nepenthes gracilis]

Hey boss,

To answer your questions:

1.) RO units can most certinaly be adapted to use with a garden hose.

2.) They can pump water INTO a container, but you'd need another pump or something to transport it back out of the resevoir. Or have a pressurized tank which can be very expensive and uneeded for the most part.

3.) I would say get a 25gpd membrane or so. If you use 3-5 gallons a day which is about as much as I use now, a 25 gallon per day (gpd) membrane will give you a constant supply of water.

4.) A good place that was reccomended to me and I plan to order from them is: http://www.spectrapure.com/

 

[BigCarnivourKid]

Quote[/b] (Sarracenia0 @ Mar. 16 2004,17:40)]-Can R/O Filters pump there own water out of a trash can or   something?

RO filters use the pressure of the water to force the water molecules through the RO membrane. To work from a trash can or other reservoir, you would have to pump the water from the container to the RO filter or the container would have to be elevated above the RO filter enough to provide the needed operating pressure. Best bet is to hook the RO filter to the garden hose or better, hook it directly into the plumbing under the kitchen sink.

BCK

 

[Sarracenia0]

i plan on getting this one. what do you think?

http://www.spectrapure.com/St_line_p1.htm

 

[nepenthes gracilis]

Sounds good to me.

Might want to make sure you monitor how much water you're using, the chlorine filter needs to be replaced every 1500 gallons, or to be on the safe side, just replace every 6 months.

 

[Lauderdale]

I am also planning on getting an R/O filter but notice the water purity depends on the number of "filter stages" (2 thru 7) on the system.
What is the minimum number of stages that will produce water clean enough for our CPs?

 

[Tony Paroubek]

I would suggest at least a 3 stage for water containing chlorines
stage 1 sediment filter
stage 2 carbon block
stage3 ro membrane
Cheaper units will combine stage 1 and 2 into a sediment/carbon filter but I would avoid them.  The sediment filter is there to keep the carbon block from getting clogged.  And a seperate carbon block will do a much better job of keeping Chlorines from the RO membrane.

For water not containing chlorines (ie well water) you can get by with 2 stage
stage 1 sediment
stage 2 ro

You will also want to look for a TFC membrane that has a rejection rate around 98% (any decent unit with a tfc membrane should be in this range).  Don't go with a CTA membrane.

I would also suggest getting a unit rated much larger than you currently need or will need in the near future.  They only produce their rated output when water temperature is around 77 and pressure around 100psi.. conditions you will not likely get from hooking to municipal or well pump supply.  So don't be surprised if you only produce half what the unit is capable of if your water is really cold or pressure low.  
Tony

 

[wolfpackgurl]

if you want to look at R/O units go to www.drsfostersmith.com and go to www.peteducation.com to find out more about R/O units.

 

[nepenthes gracilis]

Tony what exactl si the difference between a TFC and a CTA membrane? I never was really clear on that.

 

[Tony Paroubek]

TFC Thin Film Composite. An inorganic membrane that has a high rejection rate for most ions. Susceptible to Chlorine damage however.

CTA Cellulose Triacetate. An organic membrane that has a lower rejection rate but is not susceptible to Chlorine damage. Source water should infact contain Chlorine to prevent fungus/bacteria from destroying the membrane since it is made of cellulose.

 

[nepenthes gracilis]

Maybe i should get a CTA to save on carbon block cartriges ;p

Thanks for the info.

 

[Tony Paroubek]

hmm well .. the CTA membrane allows the chlorine to pass through so there other considerations as well. If I recall correctly the CTA membranes average around the high 80's-90% rejection rate.

T

 

[nepenthes gracilis]

ooh...chlrorine passes through.......

Forget it then.

 

[Lauderdale]

Tony,
You seem to have a pretty good working knowledge of these R/O filters...Would you mind going to

http://www.spectrapure.com/St_line_p1.htm

and give me me your opion of that particular filter.
That is the one that Sarracenia0 is thinking of buying and so far it seems to be the least expensive I have found on the net.
It looks to me as if it is only a two stage and I will be using it on my city water system.

 

[Tony Paroubek]

Hi Lauderdale,

Personally I would upgrade a little.  Primarily because the ultracompact unit does not take a standard filter.  They rate the carbon filtering on that unit at 1500 gallons.  It will need to be replaced much more often at the cost of $12 vs a high capacity carbon block which cost $8-18 depending on how much capacity it has.  For example the 6000gal block cost $8.  So basically it would cost you $48 in the ultracompact carbon filter vs $8 for the 6000gal one for every 6000gal run through the unit.

Also consider the ultracompact unit at $104 for 25gal/day unit
vs the compact unit which is essentially the same except it has a standard filter housing which allows you to put in the better filter for $125 for the 25gal/day.  For the $21 you get a much better carbon filter and the choice to replace it later with any of the other carbon block filters if you want ie the 20,000 gal one is only $18 so even cheaper yet than the 6000 gal one for $8 when you calculate cost per gallon.  This is the unit I am talking about 2stage standard filter

NOW the big questions is will this work well on your city water since it is only 2stage.  IDEALLY I would like to see 3 stage ie a sediment filter then the carbon block then the ro.  Without the sediment filter your carbon block is acting as both.  This may or may not be a problem.  The carbon filter is quite capable but if your water has alot of sediment then the carbon block will get plugged up prematurely and will need to be replaced before the useful life of the carbon is exhausted.  With a seperate sediment and carbon block you can replace only the filter that needs it.  
A comparable 3stage 25gal/day unit with a 9000gal carbon block would cost $146 vs the $125 3stage

If money is really tight then you can try the 2stage and see what happens.  You can always buy another filter housing and sediment filter later to add on if the carbon block clogs prematurely.

(keep in mind the carbon filters are rated for total water run through them, RO+waste)
Tony

 

[Lauderdale]

Thanks to your advice Tony I am going to upgrade a bit and this is the one I am thinking of purchashing;  

http://www.thstore.com/thstore....pID=227

I wonder if you would mind taking a look at it and giving me your opinion.  There is a list of the bad things it eliminates as you scroll down the page.

This particular site lists about ten different manufacturers and gives information on all of them...the free shipping doesn't hurt either.

 

[Tony Paroubek]

I wouldn't use that one. The inline filters will cost you an arm and a leg to replace.

Also that has post RO carbon filtering as well as Pre RO carbon filtering. Couple things here. You don't need carbon post filtering if the carbon prefiltering is working properly. Also they are using the carbon prefilter as a sediment/carbon filter which means it is really doing the job of what 2 filters should do. This can lead to compromises. It may not work as effectively or it may clog sooner requiring costly filter replacement.

You would be much better off with a standard canister prefilter and no post filter. You can get a much higher quality carbon prefilter with the 2stage spectrapure the 60gpd is less than the 75gpd on this other brand with the inline filters and it will cost less to replace filters when they need changing. Not to mention the high quality carbon block prefilters will need changing less often. And since they are rated for amount of water they can process you can actually calculate when to replace them. Instead of just doing it every 6months like this other unit suggests even though it may be too long to wait or not totally used up depending how much water you process.

As for that list of all the stuff it removes... Any good quality unit will remove the same stuff to the same degree.

There are other companies that make nice units besides spectrapure. Any good aquarium magazine will have adds from them. You can also get nice units from aquarium supply stores made by Kent marine. The thing to look for is the canister filter that screws apart. They are an industry standard and take a 2"x10" filter. You should have at least one of these and a good carbon block filter (not granulated carbon). Ideally 2 of these so you can prefilter the water with a sediment filter before it goes to the carbon block so you don't clog the carbon. This however is up to you. I don't know the quality of your tap water. It may be very clean of particulates in which case the sediment filter may not be necessary.

One way to test particulates is to get a very clean clear jar and fill it with water. Let any fine airbubbles rise to the surface then shine a flashlight through it horizontally. If you can see the beam in the water there are fine particles in the water. The greater the number and size of the particles the more you can see the beam and the more defracted it will look (fuzzy outline).
Tony