New Tank Ph Question

Discussion in 'Freshwater Beginners' started by jobrien929, May 24, 2019.

  1. jobrien929 New Member Member

    I've got a new Spec V that I just started cycling on Monday. I'm doing a fishless cycle and the only things in the tank at the moment are the substrate (Eco Complete), some rocks I got from my LFS, and water.
    The cycling is progressing but the pH is 8.0. I tested the tap water and it's 6.8 so something in the tank is raising it. Is this something I should be concerned about? If so, what should I do about it?

  2. Starflyr3 Valued Member Member

    What kinds of rock are those?

  3. Morpheus1967 Well Known Member Member

    Yep most likely the rocks. Also, those rocks are taking up a ton of space in that tank. I would bet at least half of the space is rocks. Keep that in mind when stocking.

  4. jobrien929 New Member Member

    No idea. Some kind of sedimentary rock. I read all kinds of warnings about not using rocks you just find outside somewhere so I bought them from my local aquarium shop. Here's a closer look:
  5. Morpheus1967 Well Known Member Member

    Maybe set a glass of water out from your tap. Wait a few days and test it. Maybe there is something in the tap water that is causing the pH to rise.
  6. Chanyi Valued Member Member

    It's the rocks (limestone based = increase in carbonates in water = increase in kH and pH) and it's because you are measuring tap water without letting it de-gas.

    Tap water can contain lots off CO2 which will drive pH down, so let a glass sit out for 24 hours before testing, it will more than likely rise in pH as the CO2 off-gasses.
  7. Starflyr3 Valued Member Member

  8. jobrien929 New Member Member

    The tank is in my office so I'll pour a glass today and check it when I get back from the long weekend.

    Is having the pH that high something that needs to be corrected or is it ok the way it is?
  9. Chanyi Valued Member Member

    You won’t be able to correct it leaving those rocks in there.

    If you remove the rocks (removing the buffer) the tank water should settle out at what your degassed tap water’s pH is.

    If you want to further drop pH, you will have to remove carbonates from the water in a safe manner - RO water reminerized with Ca, Mg and enough kH for 0.5 - 1.0 degrees would yield a pH slightly above 7. You can mix RO and tap water to yield a reduced pH depending on how much RO you mix in. You can, but this isn’t for a novice, use HCL to drive away carbonates, which is likely not the safest way to do so.

    Or, you can leave everything as is. Most commonly available plants / fish are perfectly fine in a wide range of pH as long as the pH is stable and consistent.
  10. jobrien929 New Member Member

    I think we can let the rocks off the hook. I tested the tap water that sat out over the long weekend and it came out 8.0 - same as the tank was. The tank itself has actually edged down a bit to 7.8 as it continues to cycle.
  11. Chanyi Valued Member Member

    See original quote minus the removal of the rocks portion ;)