What’s a good level to have on TDS with RO water?

[Buckeye Hydro]

How many GPD is your membrane rated for? Do you know the make of your RO membrane?

A 75 gpd Dow Filmtec membrane gets a 98% rejection rate. So at an incoming of 160 tds from the tap, your RO membrane should be producing no more than 4 tds.

10 tds from 160 tds source water means a paltry 93% rejection rate. Seems pretty low for a new membrane IMO.

75 Filmtec's are actually rated at 99%.

Russ

 

[Scrubber_steve]

75 Filmtec's are actually rated at 99%.

Russ

I'll have to buy one

 

[Scrubber_steve]

75 Filmtec's are actually rated at 99%.

Russ

At what ratio to flush water do you get that reduction? Or doesn't that matter?

 

[Emma01]

My TDS post filters and pre DI is 5 today......
It seems to be working! That’s 24 hours of run time.

Question.......
I’ve purchased an in line TDS meter. I know where to place the in line, but should I place the ‘out’ sensor pre or post DI pod? Any suggestions?? I also have a handheld TDS meter that I could always test with also.
Thanks

 

[Water Dog]

I’m assuming that you got a 2 stage inline TDS meter. I would put the first sensor post the RO membrane and the second sensor post the DI stage. That way, you can always keep tabs on your RO membrane performance as well as your DI resin performance. The handheld can measure your tap tds and verify post DI stage water quality as well.

 

[Buckeye Hydro]

I'll have to buy one

https://www.buckeyehydro.com/residential-ro-membranes/

 

[Buckeye Hydro]

At what ratio to flush water do you get that reduction? Or doesn't that matter?

The standard Filmtec test condition is a 5.5:1 ratio

 

[Buckeye Hydro]

My TDS post filters and pre DI is 5 today......
It seems to be working! That’s 24 hours of run time.

Question.......
I’ve purchased an in line TDS meter. I know where to place the in line, but should I place the ‘out’ sensor pre or post DI pod? Any suggestions?? I also have a handheld TDS meter that I could always test with also.
Thanks

You can expect membrane performance to improve and stabilize over the first 6 to 24 hours of run time.

With an RODI system you want to know TDS in THREE locations: tap water, RO, and DI. If you bought a meter with only two probes, I'd choose the RO and DI, and use your handheld to check the tap water when needed.

Russ

 

[Ashley Kekua]

You want a Deionized for to be ensure your water be purest ever coming out of it for your fish and corals!!! Need RODI not juss with RO not enough for your precious corals!

 

[Emma01]

You want a Deionized for to be ensure your water be purest ever coming out of it for your fish and corals!!! Need RODI not juss with RO not enough for your precious corals!

Only the best is good enough for my babies!

 

[Scrubber_steve]

https://www.buckeyehydro.com/residential-ro-membranes/

I'll need to find a distributor in Oz

5.5 to 1 ratio. Could that be decreased with a source water of only 50 TDs?

 

[Buckeye Hydro]

I'll need to find a distributor in Oz

5.5 to 1 ratio. Could that be decreased with a source water of only 50 TDs?

Absolutely! Only part of that 50 (less than half) will be hardness, so you are likely less than 1 grain per gallon (17 ppm) of hardness. With that sort of water you could likely get away with a 2:1

 

[Scrubber_steve]

Absolutely! Only part of that 50 (less than half) will be hardness, so you are likely less than 1 grain per gallon (17 ppm) of hardness. With that sort of water you could likely get away with a 2:1

Thanks for your great info.

 

[Emma01]

Finally managed to get my TDS down to zero with addition of the DI pod! Thanks everyone.

 

[Buckeye Hydro]

You'll want to orient that DI stage VERTICALLY, with water flow moving from the bottom towards the top. You might want to consider adding a pressure gauge that reads the pressure after the carbon block and before the RO membrane.
https://www.buckeyehydro.com/pressure-gauges-1/

Russ

 

[Emma01]

You'll want to orient that DI stage VERTICALLY, with water flow moving from the bottom towards the top. You might want to consider adding a pressure gauge that reads the pressure after the carbon block and before the RO membrane.
https://www.buckeyehydro.com/pressure-gauges-1/

Russ

Hi
Out of interest, if I put it vertically, is it ‘better’ clearance, or is it to do with the pressures of the pod?
Thanks
Emma

 

[Buckeye Hydro]

Emma - Horizontal DI's are a fundamental design error. Has to do with the water channeling through horizontal DI stages.

Russ

 

[Emma01]

Emma - Horizontal DI's are a fundamental design error. Has to do with the water channeling through horizontal DI stages.

Russ

Hi Russ,
Thanks. I’ll switch it to vertical.
Thanks

 

[hawkeye792001]

If you are getting 0 TDS after the RO membrane, then you really dont need the DI resin. WWC has the same situation. (I'm sure they also did ICP testing to be sure)

After TDS creep my RO comes down to 1 TDS and then 0 after my cation, anion sections, and 0 after the mixed bed. (Look at the BRS 7 stage RO/DI you tube video.)

 

[Emma01]

If you are getting 0 TDS after the RO membrane, then you really dont need the DI resin. WWC has the same situation. (I'm sure they also did ICP testing to be sure)

After TDS creep my RO comes down to 1 TDS and then 0 after my cation, anion sections, and 0 after the mixed bed. (Look at the BRS 7 stage RO/DI you tube video.)

Hi my TDS was 4-5 pre DI so and 0 after DI. Looks like the DI has to stay