any suggestions for RO units?

[kevinpo]

I also like the ARS (Aquatic Reef Systems) RO/DI units and recommend using the DI filter.
TDS out of the RO membrane depends on several factors one of which is supply water pressure. At 60-80 PSI the unit will produce more clean water but the life of the RO membrane will be reduced. Over time (this can be quite short depending on the amount of water you make up) the TDS out of the RO can rise as the pore holes are stretched faster by the higher PSI.

Using a 1 micron particulate and a one micron carbon filter with a supply PSI of 54 @45F you should see about 3-5 TDS with a tap water of 60-175 TDS. This is when running a 4:1 waste to good ratio.

I like to have the back flush kit and the adjustable flow restrictor to set my reject rate and help preserve the life of the RO membrane so I sell the units with these on them (also a PSI gauge and clear canisters are a must IMO).

I also would buy a 50 or 75 GPD unit as they are only $20 difference in price (most GPD rating are established using 70F water and 60 PSI. In practice most people hook them up to cold water and have lower PSI. This reduces the output by as much as 50% (except when you don't watch, then it quickly overflows your bucket onto the floor )

Here is a link to some diagrams of an RO membrane showing how it works. if you scroll down just below it there is another link titled Reverse Osmosis Rejection Rates that gives you a chart.
http://www.aquaticreefsystems.com/About_Reverse_Osmosis.htm

JMO,
Kevin
PS: I had a link to a great article on the workings of RO/DI (with pictures ) I just can't seem to find it right now.

 

[fishermann]

I agree Kevin, i think they make the best one, i couldn't remember the name other then i had his invoice which has cirrus technologies on it, guess i could have went to reef central, but what can i say, it must be age.LOL. I have the same setups on my unit that you mentioned and John also put a bypass valve on so we can get RO water for drinking. I just talked to him on the phone and he says depending on a few variables a general rule of thumb is that thru the first two cartridges then out of the RO you should get 5 to 10% tds reading of the reading of the supply water, other words the RO unit well take out 90 to 95%, the rest is taken care of by the DI cartridge. I just threw a rough nbr out last nite on mine which i flush twice a month 0f 5to6 tds. I tested tomorning coming out of the RO is 3, so with a supply of 40tds i am rite in the ballpark with a 4to1 ratio. You can get it lower, but if i'm not mistaken you would have to up the waste ratio. Is this the unit you stock Kevin? and if so do you keep the DI cartridge that doesn't turn color, but last longer, and needs less initial flushing that he sells? John

 

[DonW]

I guess I would question the GPD ratings. My instruction say to connect it to a cold water line. At times the water is pretty darn cold but I dont think its ever 70.
So if putting in cold water cuts it up to 50% and you need a 25 then you have to buy a 50????
Why dont they just correct for average water temps. Myself can only get 10 per day out of a Kent 25 at 60psi. That worked ok for my small tank but now that the bigger is up and running I could use the actual 25.
If I'm understanding kevinpo correctly I need to now buy at least a 50gpd to get what I thought I bought.


Don

 

[kevinpo]

I carry the Oceanus model with the back flush and the adjustable flow valve. I carry both the color changing and non color changing cartridges.
40 TDS out of the faucet is great! The west side of the state (WA) also has low TDS as a rule. Here on the east side most of our water comes from the Rathdrum Prairie Aquifer (42 miles long) located about 400' down with a high mineral content so the TDS averages 75-180 depending on the time of year (when the runoff is high/low).
Many of the smaller water companies that service less than 2,500 households do not chlorinate. They just pump directly from the aquifers so our carbon has a longer life. I have a customer in NW Montana that has a well with TDS running in the low 300's OUCH! RO cartridges don't last long for him. Many of the wells that are outside the valley here are located over basalt and the iron content is very high. Their sediment cartridges turn bright orange in less than a month. Most of those people filter even their drinking water but their toilets and tubs turn orange . I can only imagine the algae problems they would have in their tanks without filtration.

Regards,
Kevin

 

[kevinpo]

Now why would they want to do that? That would be way too easy for us. For advertising purposes the bigger the number the better. J/K In their defense water temps across the country varies quite a bit depending on the season and how the water co. stores the water. In the west large drinking reservoirs are the rule but in other areas where there is less room small water storage tanks are used placed high in the air. In the hot summer they can get to 70-75 degrees depending on ambient temp and consumption rates.

Regards,
Kevin

 

[cdeakle]

mattseattle,

Great minds think alike! =)

 

[DonW]

I guess something I'll never quite understand, my cutomers are happy getting what they paid for. We should'nt have to move to a outdated town in Nevada to get advertised output.
But oh well. Am I correct in assuming if I want 35 per day I should spend a few more dollars for a 60 or 100.

Don

 

[fishermann]

for a few dollars more you get alot more for those times you may need it, its always nice to have the ability to make lots, i opted for the 100. John

 

[NaH2O]

Since this thread was started, I became very interested in how the deionization process actually works. But since we are also talking about reverse osmosis, I thought I would put a little information on this as well. I have been reading and reading about this....my brain hurts

There are 2 types of reverse osmosis membranes. One is called cellulose triacetate (CTA), and the other is called thin film composite (TFC). CTA membranes don't filter as well as TFC membranes do....CTA rejection rates ~90-95%, while TFC rates at ~95-98%. CTA membranes also break down from bacterial attack, where TFC membranes are impervious to it. One more thing about TFC membranes....they are sensitive to chlorine and it can damage the membrane if there isn't a properly functioning carbon pre-filter. Reverse Osmosis works by the force of water under pressure against the membrane, which will allow the passage of water molecules, but reject most of the larger contaminants. By using reverse osmosis prior to deionization, the resin of DI will last longer then without RO. RO still allows some contaminants through in trace amounts....which the DI will pick up and clean out the rest of the water.

There are 2 types of DI units. One is a mixed bed, which is a single chamber with a mixture of anion and cation resins. The other is a separate bed unit, which contains 2 chambers - one for anion resins and the other for cation resins. DI utilizes a 2-stage process that removes ionic material remaining in water after RO, for example. The resins only last so long before they need to be replaced. What happens is the Cation resin exchanges positively charged ions for H+, and the Anion resin - negatively charged ions for OH-. Cation resins release hydrogen (H+) in exchange for cations, while the Anion resins release hydroxide (OH-) for anions. The hydrogen and hydroxide then combine to form H2O. - I know, I know....what did she say? lol

Something interesting I came across was that silica seems to be one of the first contaminants to leak past RO/DI. This is because silica is loosely bound to the resins, so when stronger binding materials come in, the silicates will lose their place and start to break free of the exhausting resin.

I found an article about A Study of Silica and RO. I'll touch on a couple of points. Silica is found in 3 forms: reactive, colloidal & suspended particles. The colloidal silica causes problems when it comes to water treatment because of its stability as an un-ionized compound....the difficulty is in removal by means of ion-exchange processes. Silica breakthrough (as mentioned just before) is usually the first to occur, and the use of reverse osmosis prior to deionization aids the process by reducing the silica load on the resins. As a side note, some think silicone dioxide (SiO2) is a challenge due to a similarity of H2O.

Fundamentals of Osmo Systems There is a chart of typical rejection rates towards the bottom of the page. If you look at the cation and anion charts you will see there are several that pass through. These would then be taken care of through the deionization process.

So, what does all of this mean? Deionization is a way to finalize the process of removing contaminants. Reverse osmosis does a fine job, but for the 1-2% (maybe more in some cases) that get through, it would be worth it to remove the remaining bits. For someone like me who has a TDS reading of 456 (taken just a little bit ago) going into the unit - I'm going to rely heavily on the DI process. Someone with cleaner water would probably make it through the RO process relatively clean, but the deionization would finish off the remaining contaminants. Whatever type of unit you choose, whether, RO or RO/DI - it is better than tap.

 

[jazznreef]

Nice, thank you Nikki !

A question I have right now (coincidentally) is why my ro/di unit isn't producing very much product water. i replaced the r/o membrane two days ago and have been running it for about 15 hours. the product output is really slim, like a few gallons so far. i seated the membrane properly (i think), made sure the di filter is in the right way and have new pre filters. the unit should have had time to adjust to the new membrane but the output is really low. the unit is the kent maxima ro/di-s 60gpd. does it really take this long to get the thing running properly?

 

[fishermann]

I would double check my cartridges and make sure they are in the right way

 

[jazznreef]

seems strange to me as well... i reseated the old membrane and am running that now so i can top off the tank. i will reinsert the new membrane again after and see if it works better then. it's gotta be that or maybe a faulty membrane. it just can't take that long to hydrate and work properly. i think i need a meter too so i know when these membranes are finished.

 

[NUGIO]

www.airwaterice.com I got the typhoon III and love it

 

[NaH2O]

jazznreef, I have the same unit. I know mine seems slow, but hasn't been running for extended periods. Try to measure what the output is, and maybe contact the manufacturer.

 

[kevinpo]

Check your input water pressure. If it is below 50 PSI you will have a slow output. Many people purchase a booster pump to overcome low line pressure.

HTH,
Kevin

 

[NaH2O]

Good point Kevin, thanks. I'll have to check into the line pressure and see if I need a booster pump.

jazznreef, I checked the instruction manual and here is what it said about reduced output:

There are certain factors that lower product water production. The first is water pressure. The ideal water pressure should be 65 psi. A water pressure of 45 psi will reduce the rated GPD by one half. The second condition is water temperature. The ideal operational temperature should be 70 - 77F (21-25C). Low water temperatures like 50F (10C) restrict the output to half. NEVER run hot or mixed hot/cold water to the unit. Only run the cold water. The third and final condition is the TDS or Total Dissolved Solids of the tap water. These units are rated for 200 ppm of TDS. High TDS can also lower output.

I believe since the TDS of my in coming water is 456 - that explains my lowered output.

 

[Curtswearing]

Great info everyone.

 

[islanddog]

Thank you for all the info! Real time reviews are wonderful. Now desision time.....

 

[Montanarocknreefer]

HI All! Great thread and information!

I got this unit 5 stage RO/DI unit from here:

http://www.inreef.com/xcart/customer/product.php?productid=16175&cat=0&page=

It is very nice and best price around!

 

[islanddog]

how long have you had it? How do you like it? Does it produce as stated?