bottom feeders, thats telboy's dept
ha ha
no seriously, harlequins are great, i have x6
i have pH of about 7.8, it's not a huge issue for Bristlenose the pH, thats my experience and from my own research.
I wouldnt adjust your pH at all, my view is either
(a) get RO water
or
(b) keep fish that can flourish ok in your normal tap water readings