Ok. Inverts are much more sensitive to water changes. Acclimating should take a few hrs. Alot of lfs keep salinty low so there water could be 1.020 and yours at 1.023-24 . Thats a huge jump
Lights on will cause algae. The ph should stabilize with water changes. Its low bc the water has been sitting. Most of those fish are compatible just not always with eachother.
Cuc you want to build up as your stock increases. Start with a doz or so
Hello jack. Lets see where to start. The rock is usuable sure. Idk if i would consider it live rock still tho. Using old sand is generally never good. Once it gets old it gets alot of bad stuff built up. I would get new argonite dry sand. Then use your rock and fill the tank. Get your heater...