TDS reading

[marvelousone]

I have been battling ugly fish tank face. So I am starting to rule everything out. So I started with the water. Water tds (hand held tester) water in ro/di unit is 146 and out in a cup is 26. I changed di resin, 2 carbon filters, and 5 micro filter. Now water out is 7. I do have a tds meter on the ro/di unit. It is reading 4 in and zero out. So do you think the water is clean and not cause problems in the tank. I would love to have zero on both meters. I have a pressure gauge but it don't work. I have pressure because I have a booster pump.

 

[bif24701]

I have been battling ugly fish tank face. So I am starting to rule everything out. So I started with the water. Water tds (hand held tester) water in ro/di unit is 146 and out in a cup is 26. I changed di resin, 2 carbon filters, and 5 micro filter. Now water out is 7. I do have a tds meter on the ro/di unit. It is reading 4 in and zero out. So do you think the water is clean and not cause problems in the tank. I would love to have zero on both meters. I have a pressure gauge but it don't work. I have pressure because I have a booster pump.

Where exactly are the TDS probes? First measure the TDS in RO membrane and out. You should have 96-98% reduction in TDS. With a boost pump it should be a problem to get 98 or even 99% reduction. I run my 6 stage with Dual ROs with a boost pump. Have 135-150TDS in and out 1. So that 99%, good performance. Then you should have absolutely zero after the DI stage. Your membrane could be damaged but won’t know unless you get exact readings in and out(before DI).

Replace the PSI gauge, ASAP.

 

[AquaFX-PB]

Exactly what Bif24701 said - We need to identify where the TDS meter probes are reading from.

Example on a properly working RO system -
Tap Water: 160
RO water: Look for at least 90% rejection. Most membranes will offer more than that, I wonder what PSI Bif24701 is running at? Usually you will only see the best rejection upwards of 80psi.
DI water: Zero - you should see a zero, if not the DI resin is exhausted or the TDS meter needs calibration are the 2 most common answers.


4 in and zero out??? sounds like maybe the 4 is your RO membrane (hopefully) and the zero is your RO/DI water. which starts to sound like the TDS meters are just disagreeing with one another, grab some calibration solution and calibrate the incorrect meter.

+1 on the pressure gauge, make sure you use a liquid filled one when using it with a pump.

 

[marvelousone]

Where exactly are the TDS probes? First measure the TDS in RO membrane and out. You should have 96-98% reduction in TDS. With a boost pump it should be a problem to get 98 or even 99% reduction. I run my 6 stage with Dual ROs with a boost pump. Have 135-150TDS in and out 1. So that 99%, good performance. Then you should have absolutely zero after the DI stage. Your membrane could be damaged but won’t know unless you get exact readings in and out(before DI).

Replace the PSI gauge, ASAP.

Ok water in before membrane is 146. After membranes is 4 and after di is zero. That is with the dual tds tester that is on the unit. Using the hand held tester after the di reads 7. Maybe the hand held tester is not right.

 

[rock_lobster]

Ok water in before membrane is 146. After membranes is 4 and after di is zero. That is with the dual tds tester that is on the unit. Using the hand held tester after the di reads 7. Maybe the hand held tester is not right.

Both TDS meters should read the same in the same sample of water. That means you need to get a third one.

 

[Big G]

Ok water in before membrane is 146. After membranes is 4 and after di is zero. That is with the dual tds tester that is on the unit. Using the hand held tester after the di reads 7. Maybe the hand held tester is not right.

Here's a link that discusses "recalibrating" a TDS meter. Hope this helps. Cheers!

 

[bif24701]

Right. Need to be sure you do have 0 TDS and looks like you may need to just replace the old meter on the system. Look at the triple meter at BRS, also don’t forget a pressure gauge. Make sure you are getting very fresh samples as high purity water will quickly absorb and ions it possible can. Not a bad idea to get chlorine test strips also to ensure none is getting past the carbon, that can destroy a RO membrane.

 

[AquaFX-PB]

No need to buy a new meter if you have 2 already, seems kind of crazy to have a bunch of test instruments that are no good.
Re calibrate BOTH meters (if need be, at least verify the calibration of both and adjust the meter that is off)

I also noticed that triple meter is less $ on other sites, so shop smart if you're getting another one!
But I would make good use of what you already own!!