Ro Water Ph Increasing After Some Time. Important

Discussion in 'Freshwater Beginners' started by Gohi, Apr 27, 2019.

  1. Gohi

    GohiNew MemberMember

    What can be the reason for the Ph to increase to 8.2+ after 2-3 days. I have RO water with tds around 40. The ph increase even if water is just placed in an empty container without any addition of substrate or anything.
  2. david1978

    david1978Fishlore LegendMember

    This maybe a stupid question but what's your ph without running it threw your ro unit?
  3. AquaticJ

    AquaticJFishlore VIPMember

    If the RO has a TDS of 40 you need to replace the filters in it.
  4. OP

    GohiNew MemberMember

    around 7-7.5

    tried with water having tds 6-10, but same issue
    Last edited by a moderator: Apr 28, 2019
  5. Basil

    BasilWell Known MemberMember

    Is this your RO unit? Or purchased RO water? If it’s your unit, what is your source water, well or municipal?

    I have the same issue with my RO/DI water. My well water is very acidic at less than 6 so even after aerating with a sponge filter in the brute trashcan, the ph only comes up to 6.4-6.6. So I was adding the recommended amounts of buffers to bring my water change water to ph 7 and GH/KH at about 4. But after a day of so, my tank ph would climb.

    So I did about 2 weeks worth of “experiments” to figure out just how much Seachem equilibrium, alkaline, and acid buffer to add to keep the pH no higher than 7.4 but maintain enough KH to keep the ph stable. I ended up aerating my mixing buckets and checking after 24 and 36 to monitor how much the ph would rise after more aeration as in an aquarium. And those amounts seem to be working in my tanks (Fingers crosses!!)
  6. OP

    GohiNew MemberMember

    Thanks for the reply. the ro water is processed from a little bit saline water. I am looking for a way that would be natural and buffer or chemical free.