My blue tang(in he/hers early 20s) is the same. Some times it’s twice a year other times it might be 3 or 4 times year. I don’t change up the feeding. Normally goes away in a week or so.
Wanted to see if I could squeeze out some more growth and wanted to mimic the temperature that most corals are growing in nature. With that said the same coral can grow in different temperatures. But that's just me.
I bought two but I have been using the first one that I have attached a link for.
https://www.amazon.com/gp/product/B07PP58YFJ/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&th=1
https://www.amazon.com/gp/product/B07GBYXD7Y/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&th=1
I went yesterday at 12:30pm and negative tide was at 1:46pm at -.7ft. Tomorrow and Monday would have been better they will be -1.41&-1.46. It was Pillar Point.