TDS at 16ppm. Is that ok?

[arminkropp]

Wondering if a TDS reading of 16-18ppm is alright. My tap water is absolutely horrid at 560-580ppm.

I just checked my TDS after the membrane but BEFORE the DI. Getting a reading of 36ppm. That works out to a 94-95% rejection considering feed water is going in at 560-580

Now looking at my DI closer, I'd say its close to 80-85% exhausted. I know I'll need to replace it, but am I depleting my DI resin prematurely with my TDS at 36ppm going in to it?

Whats normal. Or is this just "My" normal seeing my feed water is so poor.

I cant see anything else wrong, is 16ppm safe to use?

TIA

 

[Phranque]

With a FOWLR you'd probably be OK, but for a reef, 16-18 TDS is not good.

I have 450-500 tap TDS, and my RO is 3-4 TDS before going into the DI canisters. So, yes, 36 TDS will definitely deplete your DI resin quicker. It sounds like you are due for a complete filter change, not just the RO membrane. Before the RO you should have a sediment & carbon cartridge... if you have high chlorine in your water, or you make a lot of RODI, your carbon may be depleted. If this is the case, chlorine may be getting to your RO membrane, which is very bad for it.

 

[arminkropp]

Hmmmm, I did I complete filter change and membrane before filling my 80gal a month ago. Could I have a bum membrane?

 

[arminkropp]

I should also mention that a have a 5 micron, and 2x carbon filters before the membrane

 

[Phranque]

Hmmmm, I did I complete filter change and membrane before filling my 80gal a month ago. Could I have a bum membrane?

Certainly a possibility, but rather unlikely....... Where are you buying them from?

I should also mention that a have a 5 micron, and 2x carbon filters before the membrane

Similar set-up to mine.... You're not going to have burnt up 2 carbons in 1 month.


Short of having a bad membrane, it comes down to flow. What system do you have (brand & gpd rating), and do you happen to know what your water pressure is coming into the system?? About the only thing I can currently think of off the top of my head is that if you don't have enough pressure, the membrane isn't getting rinsed/flushed properly.

Also, an improper sized flow restrictor on the waste line can cause problems.

Are you letting the unit run for a few minutes before testing TDS after RO..... When mine first starts, it will read up around 50-75, but work it's way down to 3-4 after a couple/few minutes.

 

[arminkropp]

My RO unit is made by Aquasafe. And the filters and membrane kit I bought off Amazon and are purenex Purenex 2C-S-IM100 100 Gpd Purenex Residential 5 Stage Reverse Osmosis Water Filtration System Set - Amazon.com

I'm thinking its a crappy membrane ( think it said Hydrotek on it and came with the amazon kit) my last membrane was 5 years old (Applied Membranes Inc.) and even when my DI resin was depleted I still got 3-4ppm TDS.

I'm guessing my flow restrictor should be the right one since my last membrane was 100gpd aswell. Now my decision is do I just get a new QUALITY membrane or a completely new kit? This Spectrapure refurbs are looking pretty good......

I have a storage tank and my reading there is 16ppm. I'll let my water run for a bit and test again straight from the membrane after a couple minutes to see if I still get 36ppm.