Is this normal?

i noticed after i installed my dual inline tds meter to my ro unit (coralife pureflo2 3 stage 24 gpd) that when i first turn on my water supply the output tds meter reads high (2-80 ppm) for about 5-10 mins. is it normal to take a few mins to get it down to 0-1 ppm? thank you in advance for replys

 

no. are you sure you're not looking at the input? I'm not a fan of turning off the water supply to these units. I stop the flow on the output, not before the input.

Are you using all new filters, membranes?

 

Anything other than 0 isn't normal. Like stated above if your connections are right it's time to change cartridges and resin. Also might be a good idea to go to HD or Lowes and pick up a handheld TDS meter and check the water in your jugs or reserve before adding it. You might be suprised at what you find even when your in-line meter is reading 0's.

 

The instructions for these models specify that the 2 pins are hit by the water in a specific configuration. (Unfortunately, I cannot remember if it's parallel to the water flow or perpendicular). Are the pins correct according to the directions?

 

It's perpendicular.

 

i dont think i am. the inputs generally read 110-180 ppm (after 1min to hours running )the output reads 1-0 ppm after running for 10min or so.i put a T in my cold water supply line under my bathroom sink then a shut off valve this is before my ro unit. i'm not sure i'll have to look when i get home how to move the valve post filter. one line filtered and 2nd unfiltered you know?

 

this i s a fairly new setup.3 months old bought new. yes i remember the pin setup your talking about pretty sure i did it right seemed simply enough. maybe the probes got twisted? idk i can check that out this evening

 

What you are seeing is perfectly normal and is true of all RO membranes. it is what we call "TDS Creep". TDS creep occurs every time a RO membrane is shut down and sitting dormant. Water osmoses, creeps or moves from one side of the membrane to the other, untreated to treated in this case, and can not be prevented. This is why it is far better to run the RO system for longer periods or time each usage so you dilute the effects of the TDS creep. Using a RO hooked to a float valve can lead to a buildup of TDS in the storage container when it is cycling on and off frequently with only very small drops in water level. A solenoid valve and float switches are a better option since you can set the switches are greater distance apart so your level drops significantly before the RO comes back on to replenish the storage tank. This is also why drinking water pressure tanks are not a good idea with reef systems either RO or RO/DI as they tend to cycle a lot which concentrates the TDS creep. DI resin exhaustes much quicker too since you keep sending it small batches of high TDS water.
One thing that will help if you make water manually is to run the treated water to waste for a minute or two until you see the TDS drop to normal before filling your bucket or storage reservoir. Using a flush valve may help a little with this process but it only flushes the exterior of the membarne and not the interior or treated side where the TDS creep resides.
If you are automated and don't monitor the RO starts and stops the best thing again is to make larger batches so the TDS is diluted.

 

AZDESERTRAT I was hoping you could help. Ive been reading your posts for months and you seem very knowledgeable on filters. thanks for your help.

 

No problem, hope that explained it.