Question

[Hard-Rock]

I have a small RO unit and well water .I have 198 TDS out of the tap.38 TDS after my RO unit .I wanted better so I bought a DI add-on.0 after the DI now .I installed the add-on last Thursday .After 40 gallon and not even a week over half of my DI resin has changed color .O the RO unit was bought as a drinking water set-up.Will the membranes be differant on a drinking unit and a unit made for aquariums?What do I need a whole new unit,a new membrane?

[Thefilterguys]

You have several factors at play here. Your membrane is only operating at 85% but part of it may be low pressure. Filmtec membranes are make to operate at 50 psi and all others at 60-65. It is not uncommon to see 30-40 psi with well pumps. If you have no other water chemistry issues(CO2) you can only expect to see about 170 gallons of product water before exhaustion with a TDS of 38. CO2 issues are common in well water and will exhaust your resin much quicker.

It is also possible your membrane is shot but I would look at the other items first, pressure being the biggie. Give me some feedback on things.

Jim

[Saldarya]

Michael,

As an additional comment, I too have well water and I go through about 1 DI refill every 110 gal of water produced. My only solution thus far for aquarium use is to produce about 50 gals at a time through the membrane into a tub of sorts, aerate it for 24 hours, then use a small PH to pump that water through the DI cartridge. That will resolve the quick use of DI resin due to CO2 issues, which I woudl almost guarantee you is your problem.

[Thefilterguys]

Bobby thanks for jumping in I never have anyone report back with their success in off gassing the CO2. Most people just bite the bullet and buy the resin as they feel off gassing is too much work but it does work.

Jim

[Hard-Rock]

Aerate ? with a air pump and one of those little blue air stones.

[Thefilterguys]

If you have high CO2 you can make RO water and add an airstone to blow off the CO2 gases. Once you have blown off the CO2 you pass your water through the DI resin. It works very well but just requires another step in your water making process.

CO2 does not have a TDS reading but affects the anion capacity of your DI resin and can cause rapid exhaustion with as few as 60 gallons of production.

Here is a link to a CO2 calculator

http://jerbaker.dhs.org/fish/calculators.html


Jim