Ro/di

[BeanAnimal]

2 Observations:

1) the membrane is at best 95% efficient. A DOW filmtec membrane would yeild a better rejection rate and be less hard on your DI resin.

2) Your DI resin looks to

A) either be partialy exhausted.
B) allow the dirty water to BYPASS much of the resin due to the poor horizontal resin chamber design.

The output fron the DI should be 0, esp with an input of 8 TDS.

Your membrane was never any better than 95%, so when it is time to replace it, go with the DOW filmtec.

If you have never changed resin, it is time. If you have changed resin, then it is time. In either case, you need to add a vertical RESIN chamber that fills from the outside and pushes the water up through the resin (like on the more expensive units). This will ensure the resin is used uniformly and no channelling or bypassing occurs.

Bean

 

[hllywd]

Hey Bean, Thanks for the input I really like the horizontal vs vertical agruement, it makes sense. I assume with that arguement the DI resin is a loose fill substance? If so maybe I'll remount the DI can and retest...
Thanks, Tim

 

[BeanAnimal]

Tim,

It may help a lot to remount the DI. The purpose built vertical canisters and DI inserts work much better, but at this point it is worth a try. If the resin is loose, then it may still channel around it. Whatever you do, check the TDS, it may rise for a short time if you monkey with the resin.

The resin tends to settle in a horizontal chamber and the water can flow somewhat over top of it (or a large portion of it).

When you get a new membrane, make sure you get the Dow Filmtec 75GDP.

Have a nice day!