what do i need in a RO/DI? 2stages?3,4?

[FLOPPYFISH]

just wondering how much of a filter i really need, i don't now water quality, because i haven't moved in to new apartment. but wondering anyway, water around here isn't the worst you've ever seen so make a recommendation for medium quality tap water.
Thanks for the help

Matt

 

[FLOPPYFISH]

Oh yeah, its for a 15Gal too if that helps any?1

 

[liquid]

I went with a 4 stage SpectraPure RO/DI + purity monitor + flush valve for my needs and I'm very happy with it. SpectraPure has been in the water purification business longer than AquaFX and ReefPure, plus neither one of these companies were around when I purchased my unit, so I purchased a SpectraPure.

RO/DI + purity monitor: http://www.premiumaquatics.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=PA&Product_Code=SP-CSP-DI-80&Category_Code=SP4stage

Flush Valve:
http://www.premiumaquatics.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=PA&Product_Code=SP-FLUSH-KIT&Category_Code=SProac

Whatever unit you go with (even if it's not SpectraPure), make sure to get the flush valve to extend the life of your RO membrane and get either the purity monitor or TDS meter to monitor your water output.

FWIW, I highly recommend going w/ a 4 stage unit so you get the sediment prefilter (filters out the particulate matter), carbon block filter (filters out chlorine and some organics), RO membrane and DI cartridge. I recommend DI as the previous components do not completely pull out nitrates, phosphates, and silicates.

Here's what SpectraPure has to say about filtration methodologies:

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

In the pre-filtration stage, tap or well water first passes through a sediment filter where silt, sediment and particles (like sand and clay) are removed. Water is then forced through a high-efficiency carbon block filter where micro-pulverized carbon efficiently adsorbs chlorine, chloramines, pesticides, and other harmful organic chemicals and pollutants.

The pre-filtered water, now stripped of membrane damaging particles and chemicals, flows into the RO membrane modules where pure water molecules are forced through the RO membrane, flushing salts, hardness, bacteria, viruses, pyrogens and other impurities from the system.

Reverse Osmosis membranes, although very good at removing contaminants, still allow trace amounts to pass through. Nitrates, phosphates and silica are among these substances not fully removed. By further processing RO water through multi-layered, mixed-bed deionization cartridges, even difficult to remove chemicals are reduced to virtually undetectable levels. The Deionization cartridge contains resin beds of positively and negatively charged polymers which react with contaminants to chemically remove them from the water stream. The result is ultra-pure water that is extremely low in contaminants.

hth

Shane

 

[theonella]

I would agree with liquidshaneo. The four stage are the best, and definitely get a TDS meter, which really measures the resistance of the water to electrical current. Pure water does not conduct electricity, but ionic impurities in the water will allow it to pass some current. So, you will have some objective measure of the water purity that your system produces. If things start to go south, you will know before you use "bad" water, and can perform the required cartridge replacements.

The prefilters (usually 1 micron sediment and 0.5 micron carbon block) for the RO cartridge are a must. RO cartridges are on the expensive side, so you want to get the maximum usage. The prefilters are relatively less expensive.

Depending on your budget and how pure you want the water, addition of a DI cartrige is an option as a final purification stage to remove any ions that the RO membrane didn't get.

One other important thing to note is that the "rated" gallon production of a system is based upon a certain input pressure. If your pressure is less than the rated pressure, the water production will be slower than you expect. You might want to test the pressure at your intended installation location to make sure it is not unreasonably low. Also you will need to be able to drain the bypass water, which is typically about 4 times that of the purified water. I normally use mine to water the garden.

Finally, you might look into buying RO/DI water from you LFS, if your needs are not that great. These things aren't cheap, and need to be maintained in order to work properly.

Good luck.

[ April 08, 2002: Message edited by: theonella ]</p>

 

[Road Runner]

I also agree with the other 2....... a 4 stage is top quality.......can't go wrong!