R.o.d.i ?

[firefishred]

my tds meter reads 8ppm on the out. when should I change my filter & membrane? The maker said every 6-8 months.

 

[surf_buddy]

I'm taging along since I just got a RO/DI myself. I have 13 in 0 out.

 

[firefishred]

my in is 76 ppm.

 

[91YOTA]

most people replace cartriges and membranes at 1-2ppm.... if yours is 8ppm i would think about changing them out... how long they last depends on the incoming source water (how many ppm of tds it has) and how much water you use... someone who has 15ppm coming in and runs a nano tank may go years while someone with a 200g system who has 50ppm coming in and does regular water changes of 30-50g 2-3 times per month may need to replace the cartriges and membranes every 6 months... hth

 

[surf_buddy]

My water must be horrible! I have 60 yo steel pipes that are nice and rusty inside. I have already seen the first filter color change to a rusty color right after the first 50 gallons was made. Right now it has TDS of 13 ppm in and 0 ppm out.

 

[mmkeeper]

Can you change your di resin? Do it first, Then look to replace the charcoal and others. The membrain should last upto 5 years.

 

[firefishred]

I changed my 3 filters about 6 months ago. I don t know when the membrane was changed last. so I am thinking that its not filtering right.

 

[mmkeeper]

How long have you had the filter? Can you change the di resin?

 

[Scooterman]

Usually I change my pre & carbon filters when the pressure drops off or If I see any TDS. I use color changing DI & replace that when it is turning yellow or TDS readings above "0" I never go longer than TDS of 2. Last would be the RO membrane but usually that can last several years depending on your supply water & how often you replace the carbon, back flushing etc.

 

[jnarowe]

I have dual DI Resin chambers and when the TDS reaches 1 out of the first one, I change it. TDS is a very poor measure of water quality so IMO, any reading at all is cause for concern.

I recently sent my "Zero TDS" water to AquariumWaterTesting.com and here are the results:

Ammonia (NH3-4) ........................Good ......................................... 0.004
Nitrite (NO2)................................Good ......................................... 0.002
Nitrate (NO3)...............................Good .............................................0.3
Phosphate (PO4) ..........................Good ........................................... 0.03
Silica (SiO2-3) .............................Good .............................................0.5
Potassium (K) ...............................Low.................................................0
Calcium (Ca).................................Low.................................................0
Boron (B) .....................................Low..............................................1.6
Molybdenum (Mo).........................Good .............................................0.0
Strontium (Sr) ..............................Low..............................................0.0
Magnesium (Mg) ...........................Low............................................. 139
Iodine (I¯)....................................Low............................................ 0.02
Copper (Cu++) ............................Good ........................................... 0.00
Alkalinity (meq/L)..........................Low............................................ 0.41

 

[firefishred]

Usually I change my pre & carbon filters when the pressure drops off or If I see any TDS. I use color changing DI & replace that when it is turning yellow or TDS readings above "0" I never go longer than TDS of 2. Last would be the RO membrane but usually that can last several years depending on your supply water & how often you replace the carbon, back flushing etc.

I changed my filters (just the 3 not the membrane) 6 months ago.
what is back flushing? I dont have a pressure guage

 

[DonW]

There is no such thing as a 100% rejection membrane. For example a 98% membrane in a perfect world would would have a tds of 2 comming out if the incomming was 100. Since its not a perfect world you can expect higher due to temp and pressure.

Don

 

[firefishred]

I always run cold water to it and my in is 76 to 78. I do live in an apartment and the water pressure does drop depending on how many people are useing the water!

 

[jnarowe]

Your apartment water may not be that cold. I run 200' of 1/4" supply line inside room temp. container of water to help bring the temp. of the incoming water up a bit.