So I have been trying to lower my pH to about 6.8 because I have really high pH and hard water. I have been using seachem neutral regulator and the discus buffer to lower it. After a couple days of lowering it to 6.8, it rises after a few days. I have no rocks or stones that could increase the pH. Any ideas?
Why do you want to lower your pH?
Do you know what your GH and KH are? If yes, what are you using to measure these two?
Most often, products that are meant to change pH are meant to be a *temporary* fix, not a long term one. By using these products you are causing a swing in parameters which may not be healthy for the inhabitants and raising the TDS through the roof each time you use them. What everyone calls "pH shock" is actually "TDS Shock" - aka osmotic shock. This is the change in pressure in the water, or how hard or how soft that water is.
If you want acidic water, then it's recommended to use a buffering substrate that lowers the pH along with RO water or distilled, then GH minerals. No KH in the tank. In this way, you can better "dial in" the parameters that you want.
On the other hand, if you simply want a lower pH without using a buffering substrate, it may still be a good idea to switch to RO/distilled water and a GH/KH remineralizer. You can then add in leaves, peat moss/granules or alder cones to the water. However, by using these items, it may stain the water tea colored and you may want to consider pre-treating new water with what you have in the tank as well.