DI Resin *ADDING* TDS?!

500-1000 gallons I wish I got that much out of mine! I only get about 150gal then refill time. My tds is around 880 out of the tap so it uses it up quick. Good tip though I never thought about it leaching back out.

 

I just got my model in today and will be hooking it up soon. I also bought a handheld TDS meter and was checking out of the tap....920. Wow!

 

FishBrain - What is your tds coming out of the RO unit?

 

Posted By vikubz on 03/09/2010 11:59 AM
FishBrain - What is your tds coming out of the RO unit?
It's zero

 

Seems weird that your resin doesn't last longer.

 

I wish it did. It sucks haveing to change it all the time. It realy sucks if your setting up a new tank. I do have a tds meter and it is color changeing resin so no doubt it is depleated when I change it.

 

Check out the FAQ section on Air, Water, and Ice for some calculations on how long the DI resin should last, based on the TDS coming out of the RO unit.  Here's an exerpt:
[table]

DI Life? How long will it last?
First
of all, there are two kinds of DI filter cartridges; vertical and
in-line. Both can filter out the TDS down to zero (or very close to
it), but they have different filtering capacities.

To figure how long they'll last is simple math. Take the capacity of
the DI filter and divide it by the TDS of the water feeding it. The
lower the TDS feeding it, the longer the DI will last. This is why it's
good to have a RO membrane to remove most of the TDS before using a DI.


For Example:
The vertical DI has a capacity of 6,800 ppm. The in-line DI has
about half that capacity, so around 3,400. Let's say that the RO is
reducing the TDS down to 20. This is what the equation will look like
for each DI:


Vertical DI:

6,800 (ppm) divided by 20 (ppm) = 340 (gallons of pure [-0- TDS] water)


In-line DI:

3,400 (ppm) divided by 20 (ppm) = 170 (gallons of pure [-0- TDS] water)


There are some exceptions to this equation. Higher than usual levels
of some TDS can cause the DI to exhaust faster. It's also important to
know when to flush the membrane before starting to make RODI water.


Some examples of elements that, if in high levels, can cause the DI
to exhaust faster are: phosphates, nitrates, silicates, salt, calcium,
etc. The RO membrane can remove most of it, but the DI would have to
work harder than usual to remove it all from the water.


If the unit has sat inactive for more than one day and you do not
flush off the membrane before making RODI water, it can cause the DI to
exhaust faster as well. Make sure to flush off the membrane for one
minute per day of inactivity. This doesn't really apply to those who
use their unit every other day or every day. However, if you use it
that much, you should still flush the membrane off once a month for
about 30 minutes or so.


[/table]