TDS metter shows 40ppm, is it ok ?

[Water Dog]

Check your source water TDS. I’d like to verify that your RO unit is working correctly.

Based on the 98% rejection rate typical for 50gpd RO membranes (TW30-1812-50), if you’re getting a 25 TDS reading out of your RO unit, then that tells me that your tap water TDS reading is a whopping 1250!

If you’re gonna push 25 TDS through DI resin, you will be ripping through that resin very quickly.

 

[Gilzo]

Once again, do you have a way of testing the TDS of your tap water before the RO unit? 25 is pretty high. And you will know when to change your DI Resin when your TDS gets above 0 after the DI stage.

Check your source water TDS. I’d like to verify that your RO unit is working correctly.

Based on the 98% rejection rate typical for 50gpd RO membranes (TW30-1812-50), if you’re getting a 25 TDS reading out of your RO unit, then that tells me that your tap water TDS reading is a whopping 1250!

If you’re gonna push 25 TDS through DI resin, you will be ripping through that resin very quickly.

getting around 400 ppm straight from the tap


how is this one?
https://www.ebay.com/itm/10-Refilla...362502&hash=item4653f38408:g:GXEAAOSw~RVaGEds

i will replace one of the carbons with it

 

[Water Dog]

Okay, I just looked at the specs for a 50 god membrane and it should get between 98 to 96% rejection. So at 400 tds source water, you should get product water between 8 and 16 tds. The 25 tds that your getting seems unusually high.

As far as the DI cartridge that you linked to, that should work. However, you’ll have to reroute your system’s plumbing.

Currently you have this -

sediment filter > carbon block > canon block > RO membrane

You’ll have to reroute the plumbing it to this -

sediment filter > carbon block > RO membrane > DI cartridge

Because of the high TDS of your source water and resulting product water, I think you’d be better served using a dual DI canister system after your current set up. Something like this...

https://www.bulkreefsupply.com/dual-deionization-canister-with-trm-1-triple-tds-meter.html

The included TDS meter will allow you to monitor resin life.

 

[Water Dog]

To improve the efficiency of your current RO system, I’d switch the membrane (Dow Filmtec) and flow restrictor out for a 75 gpd set as it should get you a solid 98% rejection rate which will help conserve DI resin down the road.

https://www.bulkreefsupply.com/75-gpd-reverse-osmosis-membrane-dow-filmtec.html

https://www.bulkreefsupply.com/membrane-flush-valve.html

 

[Opus]

Are you using an inline meter to check your tds or a hand held. If hand held are you checking in your water container or a clean glass?

You really should fix the problem and not just add DI. My tap is over 400 and my tds after my RO membrane is 4. At a tds of 25, a DI canister will make around 175 gallons of water. My TDS of 4 will get over 1100 gallons out of a DI catridge. At $15 to $20 to refill DI, that can get expensive depending on how much water you use.

 

[Randy Holmes-Farley]

Are you using an inline meter to check your tds or a hand held. If hand held are you checking in your water container or a clean glass?

You really should fix the problem and not just add DI. My tap is over 400 and my tds after my RO membrane is 4. At a tds of 25, a DI canister will make around 175 gallons of water. My TDS of 4 will get over 1100 gallons out of a DI catridge. At $15 to $20 to refill DI, that can get expensive depending on how much water you use.

I'd be hesitant to claim it is a "problem" to have 94% rejection by an RO membrane (which the OP has). IT only claims a min of 96% rejection on NaCl, and since some things get through easier than NaCl, I would not call it a "problem".

 

[Water Dog]

I'd be hesitant to claim it is a "problem" to have 94% rejection by an RO membrane (which the OP has). IT only claims a min of 96% rejection on NaCl, and since some things get through easier than NaCl, I would not call it a "problem".

Still seems low for a 2 month old membrane, don’t you think?

OP, do you know what pressure you are pushing through the RO unit? Just trying to troubleshoot the reason why your rejection rate is out of spec for a 2 month old membrane.

 

[MTBake]

What's the psi of your incoming water? Might not be running as efficiently as it should if your psi is low.

 

[savetheocean]

I dont trust my TDS meter. I need to purchase a new one. Ive had it read 100, 0, and everything in-between. Im looking for a new one, suggestions?

 

[Water Dog]

Any temperature compensated one will work. I use an HM Digital TDS-3 meter. If you want to get spendy for a top of the line handheld, then get a HM Digital COM-100.

 

[Gilzo]

Are you using an inline meter to check your tds or a hand held. If hand held are you checking in your water container or a clean glass?

You really should fix the problem and not just add DI. My tap is over 400 and my tds after my RO membrane is 4. At a tds of 25, a DI canister will make around 175 gallons of water. My TDS of 4 will get over 1100 gallons out of a DI catridge. At $15 to $20 to refill DI, that can get expensive depending on how much water you use.

im using hend held one
check't it any possible way.

didnt get exactly what you call "a problem"

i have a 280L tank

i change around 40L weekly - 160L monthly

 

[Water Dog]

didnt get exactly what you call "a problem"

The “problem” referred to is the question of why your 2 month old RO membrane is running so far out of its 96-98% rejection rate specification.

 

[Gilzo]

The “problem” referred to is the question of why your 2 month old RO membrane is running so far out of its 96-98% rejection rate specification.

is there a - way to know that?

btw

i ordered the 2 tank DI RESIN like you guys told me to

 

[Water Dog]

With a 50 GPD membrane, you should be getting 96-98% rejection. At 400 TDS source water, you should get between 8 - 16 TDS... You’re getting 25. That’s why we’re asking you what your pressure is running rough the system, so we can troubleshoot the reason for the higher than normal TDS. At the end of the day, we’d like for your system to run as efficiently as possible to help save you the cost of ripping through DI resin at a potentially unnecessary rate in order to achieve 0 TDS water.

Something else I just thought of... what is the ratio of waste water to RO water? Optimally, it should be 4 to 1. Do you have a picture of your flow restrictor?

 

[Gilzo]

With a 50 GPD membrane, you should be getting 96-98% rejection. At 400 TDS source water, you should get between 8 - 16 TDS... You’re getting 25. That’s why we’re asking you what your pressure is running rough the system, so we can troubleshoot the reason for the higher than normal TDS. At the end of the day, we’d like for your system to run as efficiently as possible to help save you the cost of ripping through DI resin at a potentially unnecessary rate in order to achieve 0 TDS water.

Something else I just thought of... what is the ratio of waste water to RO water? Optimally, it should be 4 to 1. Do you have a picture of your flow restrictor?

it looks like 4 to 1 but i dont really know exactly

and im getting around 18-20 not from the bucket, maybe because the water was one week old so the PPM went up.
now i tested 2 days in a row and im getting 18-20

 

[Water Dog]

Without knowing your PSI running through the system, it looks like that’s as good as it will get with your RO membrane. With the dual DI canisters, you will get 0 TDS RODI water. If you feel that the rate of DI exhaustion is too cost prohibitive for your liking, consider my suggestion in post #24. I use a Dow Filmtec 75gpd membrane paired with a 55oml flow restrictor running at 65psi. My incoming is 110 TDS and I get 0 TDS RO water... and yes, I still use a dual canister SpectraPure DI system.

 

[Reef Jeff]

Make sure that when you test the output of the RO you let it run a while first. You may already be doing that, but some may not know it will always be higher if the RO unit was idle and you just started it back up and took a TDS reading right away. After startup, let it run a few minutes before you test the TDS. If you were testing it after it had been running a while then it is what it is. I consistently get 1-2 TDS output on my RO unit using well water at an input of 45-50 psi. It then goes into a dual DI setup for a total output of 0 TDS.

 

[Water Dog]

Also, now that you have a dual canister DI unit, get a 3 way valve and use it as a DI bypass. When you initially go to make RODI water, using the 3 way valve, divert the flow away from the DI canisters (into the sink or wherever). Run it for 5-7 minutes so that the initial start up water does not hit the DI resin. This initial water is full of TDS creep. By diverting it for several minutes upon startup, you are further preserving your DI resin life.

https://www.bulkreefsupply.com/3-way-ball-valve-with-john-guest-1-4-push-connect.html