Don't screw with your pH, it's fine where it's at. Mine is higher than that and my 2 EBJD's were raised in it and grew super fast. Messing with pH causes more problems than it ever solved. I agree with the poster that said your nitrate reading of 40 ppm is more of a problem than pH ever would be. That's high. Low nitrates (ie lots of water changes) is what makes fish grow fast. My 2 grew fast and did great for 9 months and then 1 died with no warning whatsoever. These aren't always the hardiest of fish and have quite a few problems.