high alk consequences?

Thanks for all your help on other issues. What are the consequences of leaving my alk at 240. As I understand it, it will help my pH stay steady but there must be other issues. I'm new to this pool stuff but this site is a great way to learn and all of you are great help and I appreciate all your input.
Thanks,
Dave

PS my numbers as of today
fc 3.5
cc 0
tc 3.5
alk 240
cal 170
cya 30
ph 7.5
temp 64
water only slightly cloudy but I can easily see the bottom and pattern on the liner of my 30' round AG

A couple of things come to mind.

With high alk, it will be harder to change your PH. Sometimes this is a good thing sometimes not. If you have high PH, then adding acid will bring down both the PH and alk, not a bad thing. However, if you ever need to raise your PH, the the alk is likely to go even higher and make it even tougher to change the PH the next time. So if your PH tends to go up over time, this may not be a problem. If PH tends to go down over time, then this could be a compounding problem.

Also, if you had high calcium hardness, which you don't, high alkalinity would make it easier for the calcium to fall out of solution (i.e. scale).

Given where your other numbers are, I would say you don't have an immediate worry but long term it may make it easier if you brought it down a bit. One thing you could do is keep your PH down at 7.2 or even 7.0 and let the alkalinity drop over time. This would also help keep the calcium in solution.

Thanks for you thoughts Mark. So far my ph has been perfect but I never thought about what might happen to my alk if I need to raise the ph.