THis tanks 3 yrs old? Well your calcium level is spot on so why add any. Then your PH if fine also why why do you want to adjust this.
is your best bio filter and will remove nitrate and ammonia but you need atleast 1lb per gallon. The lack of LR
also means a reduction in beneficial bacteria .
I didnt see any powerheads listed. With so many fish i would get some good flow in there.
You have great lighting but fish dont care about light , they would do fine under low PC
Is there a perticular problem you want to solve or do you just want to add stuff to your water?