Maintaining Alk levels

I'm using IO Reef Crystals. My ALK after a water change (30% weekly on a 24 gallon nano) always maintains at 10 dKH. Throughout the week, my ALK drops (SPS uptake and some carbon vodka dosing). Then at the end of the week, I do another water change which changes the ALk slightly. On my last water change, I noticed some STN from the base of several colonies, no burnt tips though. This appeared immediately after water change day. That was the only change I made. Yes I roll the dry salt bucket and let the mixture sit for 24 hrs at least.

Should I be maintaining my ALK according to the salt mix dose? That way when the water change happens, it does not increase dramatically.

I realize that a dKH of 7 - 9 would be ideal, but I find it too hard to manage keeping ALK at low level. I guess that means I can't go ULNS with this salt mix, or with a nano.

I'm dosing 0.01ml of vodka 3 times a week. But it is a barebottom tank and already at steady parameters ( 0 nitrate and <=3 phosphate).