What is your RO/DI TDS?

[AZDesertRat]

If your tap TDS is 600, as is ours around here in Phoenix and surrounding areas, its even more important to monitor the RO only TDS. When I had a Typhoon III RO/DI the best I could get out of the RO was 13-15 and I even changed the membrane for a new one. My DI resin lasted 150 gallons per 20 oz refill and I tried them all, Resin Depot, Buckeye, ARS and many others at the time.
I switched to the MaxCap system and with no other changes whatsoever my RO only TDS was between 3 and 4 on a COM-100 handheld meter and my very first MaxCap DI cartridge went 830 measured gallons. After that ever MaxCap DI went over 1000 gallons and the SilicaBuster DI lasts over 3000 gallons each. Its been that way ever since and I have the log books and documentation to back it up.

Don't assume that 0 TDS out of the DI means everything is OK, it could be the DI acting as a crutch propping up a poorly performing RO membrane and costing you money. Today with my MaxCap 100 UHE my RO TDS is between 2.3 and 3.2 down from a tap of 530 to 650 depending on the source blend and seasons. DI lasts over 1000 gallons, I last changed a DI cartridge in October or November of last year!

 

[fjpod]

I shoot for 0 TDS. I change out my DI when I start seeing 1 or 2. My tap water out of the faucet is about 37 here in NYC. I only have a 14 Gallon BioCube and changeout about 2 1/2 gals per week, so I only use a simple API tap water filter (which is basically a DI unit). Seeing as how my tap water is so low in TDS and my volume needs are small, I couldn't see going for a full blown RODI.

My actual setup is a regular household carbon/sediment filter first in line (cheap, $18, "five year" filter), then two API tap water filters in series. The first one having my older cartridge, and the second one having the newer one. The whole setup cost about $80 and I get at least 200 gallons per DI cartridge.

Even with my low TDS, I get a very small amount of bubble algae, and some cyano on one single piece of rock, but that could be many other issues...but my glass needs only a light weekly pass with a mag float.

 

[Connie]

Mine is at 0 with a TDS meter. I change the filters if it starts reading anything else. I use Bulk Reef Supply 4 stage ro/di unit 75gpd

 

[Zack]

My vote for 0 as well!
Reef pets, I do find it interesting that you are having such great success with such high tds. Hey if it aint broke, why fix it right!?
Great thread topic by the way!!

 

[joeyhatch11]

For those of you with a presure gauge on your system what are you getting through it without a buster pump?

 

[jdpiii3]

I always keep my tds after the DI stage at 0. I use two DI chambers when I see the first one is staring to look bad I rotate it with the second chamber then empty, refill then replace it in the last spot.