7.8 is perfectly fine, IME/IMO. Were it me in your shoes I would leave your reactor on fulltime and call it done. Sounds like it's working well for you.

FWIW, I've found that tracking pH in the tank itself to be of minimal value. (Tracking the pH in the reactor OTOH is of utmost importance. :) But the tank itself, not so much.) It doesn't really tell you anything specific, but instead is a sort of "resultant" based on other parameters which come together in concert and then forms a pH value - it's better to track those individual parameters because they tell you more - your nitrate is up, your nitrate is down, your calcium is this, your alkalinity is that .. your magnesium is such and such. And so on. I haven't bothered testing pH myself in years, except for when I've had to answer the inevitable question on forums: "What is your pH?" when asking questions on other things. :) HTH!

Just remember the most important thing here that its a Alkalinity Reactor, and if anything that you should make sure that your alk is stable then out of any of it. your tank can get stressed out pretty quick with the ALk being unstable.