I read through some of it. I hate reading ... lol Still over my head, but what I did get out of it helped. What I got was instead of raising the alk in my salt mix barrel, I should add it to my top off water barrel. We add top off water daily. So that would help it stabilize better.
In the past, I have had issues with the freshwater and pond crashing, it was due to alk problems. Our alk in the tap is only 3. I put crushed coral in the freshwater tank and a huge slab of rock in the pond, haven't had any problems since. Not sure how long the crushed coral lasts, but it's been in there for about 7-8 years now. PH is still stable.