nitrate spike could def be due to the vacuuming of the sandbed. I never ever vacuum mine, and in the past the most I have done is lightly go over the surface and not disturbing the sand at all. BUT nothing a water change or two wont cure.
Yep, lighting should have absolutely zero impact on the tangs life, he may be a little put off but it wont cause anything bad to happen. Hippos' can be really finicky though and are a weird fish. Mine jams himself in the rockwork if I walk by still, even after I have had him for several years. he also will pick up frags and hide them behind the rocks. lol I cant put frags in the tank anymore unless I glue them down now. He also doesnt like snails or hermits, I have seen him pick them up and run away with them. For sure a weird fish. lol
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.