what could be causing burning tips

[LoJack]

It has a temporary effect, so depending on when you test, it could definitely be back to normal. Its not low alk that causes the issue, its a rapid fluctuation in alkalinity that the corals have a hard time adapting to.

I personally would snip the burnt tips, I find this to be a faster solution than waiting for the coral to recover and then regrow its tips. I find that freshly cut tips tend to grow fairly quickly.

I also do not like the Hanna checkers. I have phosphate, alkalinity, and calcium but I only use the phosphate tester anymore. I found the others unreliable and had huge fluctuations testing the same water 2 or 3 different times.

I have since switched to ELOS kits and doubt I'll ever use anything else again … so much easier, and I find the results consistent