In Desperate Need of Help for Saltwater Aquarium, Kelowna

[LeanneP]

I have halide lighting that I keep on for about 5 hours a day and my temp is 78-80. I have a fan but I still seem to fight with keeping my temp stable when the lights are on.
I have been using API test kits for the ammonia testing. I am kind of surprised that this is a cycle after 5 weeks. Would they not normally happen sooner. We used the sand from the existing tank and some of the water. Everything was moved in buckets and all the corals and fish were doing great the first 5 weeks.
I was wondering if I did a 50 gallon water change would it be hard on the fish since my ph is so low. It is 7.7 and goes to 7.9 when the lights are on but has been as low as 7.5.
I have been using prime for the ammonia or should I just be doing water changes.
And Brent I would love to get some help. Where are you.

Leanne P