my first suggestion would be to replace the test strips with a more accurate test kit, often test strips are wildly innacurate at best.
if your PH is indeed 8.8 after being tested with a more reliable test kit I would suggest doing waterchanges. to get it back within range. honestly it would be very suprising if your PH was that high. also test your calcium and alkalinity, between knowing where those two parameters are you can figure out why your ph would be elevated to the point its at.