curing and ammonia- how high is too high

[Brighteyes_13]

i tested my rock yesterday and found my ammonia levels really spiked over the last week. The test only shows up to 8ppm and its at least that if not higher. I tried reading as much as i could about curing and water changes ect... gotta love it when the advice is "Water changes will help you keep the ammonia level from getting too high" but never once says what too high is. To be safe i did a 50% change today (still maxing out test).

My question is, what is too high? and what will higher sustained ammonia levels do to curing liverock? can it kill all the beneficial bacteria that cycle the rock?

im going to mix up a new batch of water to do 100% change this weekend but im worried its all for nothing at this point, and ive killed my rock.