Water General RO/DI question

[APISTOBORELLI]

All the cartridges should be universal, correct? I'm going to order from air water ice today and wanted to make sure.

Thanks.

 

[APISTOBORELLI]

This is the pack I'm planning on ordering. I should have no trouble right?

http://airwaterice.com/product/3PACK/3_Pack_Filters.html

 

[MartyM]

All of the typcial home/hobbist RO units use standard 10 inch filters.
You shouldn't have any problems.

 

[APISTOBORELLI]

Thanks Marty.

 

[JayM]

If you're replacing your RO membrane, order the 75 instead of the 100 gallon for the water general unit, the 75 gpd membrane has a higher rejection rate, and it will keep your TDS to your DI resin chambers lower

 

[APISTOBORELLI]

I wasn't planning on replacing the membrane. How often should you replace it? Is there a way to tell when it needs replacing?

 

[JayM]

The main way is a TDS meter......if you're over 2-3PPM at RO output (before DI chamber), it's time for it to go. The instructions said to replace it every 2 years, but I thought that was BS, because they have NO IDEA how much water you are filtering. My reef systems add up to over 350 gallons, and I do a lot of top off, and a fair number of water changes. I calculate at least 300 gallons per month between topoff and WC water.

I change my first 3 filters every 6 months, and the RO when the TDS goes over 3 at RO output. I am getting 1ppm TDS at my RO now, and I replaced my membrane with a 75GPD about 2 months ago

 

[APISTOBORELLI]

Looks like that's next on the list. Thanks for the info Jay.

 

[JayM]

Sorry, one last thing: don't forget to let a new RO filter run for a couple of hours after you change it WITHOUT it going through your DI....there's some kind of anti-microbial stuff that will trash it (the DI). Of course, if you RTFM, you'll know that

 

[APISTOBORELLI]

RTFM?

I think I know what that means. Too bad I bought it used and don't have the FM.

 

[nunofs]

The main way is a TDS meter......if you're over 2-3PPM at RO output (before DI chamber), it's time for it to go.

That depends heavily on the TDS of the tap water. What you have to take into account is the efficiency of the RO membrane, which are usually rated at around 95% (for the 75gpd ones, 100gpd have lower efficiency).

So if you have, say, 100ppm of TDS in the tap water, your RO water (right after the membrane) should be around 5ppm (the membrane removes 95%)... but that's a theoretical efficiency, in perfect conditions (water temp of 77 F degress, high input pressure, etc). A more normal number in this case would be some 10 to 15ppm in the RO water... and this would mean it's operating perfectly, no need to replace it.

So just make the calculations based on the TDS of your source water, it's the only way to really know when the cartridge needs to be replaced.

Nuno

 

[nunofs]

RTFM?

I think I know what that means. Too bad I bought it used and don't have the FM.

Water General have their manuals online at http://www.watergeneral.com/support.aspx

 

[APISTOBORELLI]

Nice Nuno, thanks!

 

[dedfish]

That depends heavily on the TDS of the tap water. What you have to take into account is the efficiency of the RO membrane, which are usually rated at around 95% (for the 75gpd ones, 100gpd have lower efficiency).

So if you have, say, 100ppm of TDS in the tap water, your RO water (right after the membrane) should be around 5ppm (the membrane removes 95%)... but that's a theoretical efficiency, in perfect conditions (water temp of 77 F degress, high input pressure, etc). A more normal number in this case would be some 10 to 15ppm in the RO water... and this would mean it's operating perfectly, no need to replace it.

So just make the calculations based on the TDS of your source water, it's the only way to really know when the cartridge needs to be replaced.

Nuno

I agree with Nuno. It all depends on the source and how effective the membrane is. Also if you decide to switch membranes you may want to make sure you have the correct flow restrictor to match.