Sorry... should've asked what brand your test kits were.
I don't think most here would consider 1.7-2.8 meq/l "normal". A good alkalinity to shoot would be 2.8-4.2 meq/l, which is the same as 8-12 dKh
. Sounds like maybe your alkalinity is a little on the low side, which may be from the fact that your pH is high. You can think of alkalinity as a pH "reserve"... but that's not really accurate. Alkalinity serves as a buffer to guard against pH swings.
Either way... that isn't your problem. I was just asking about alkalinity levels to try and get more data points to try and point to the problem.
You're using a pH kit/color chart for saltwater, correct?