water temperature question

[ThirdDay]

I have a 100 gal tank w/ lr & fish. I would like to add some corals also. My question is how critical is water temperature? I am able to keep it pretty constant at around 80 deg. running fl lights. I have mh light that I don't run much at all for fear of raising temp too high & I know I will need to run it if I put in corals. Do I need to invest in a chiller? Also I have water w/ high ph. Usually my ph runs around 8.6. Is this something I need to worry about? If so, how do I get it down? I have seen several additives etc. for raising, but none for lowering ph.

Thanks for any advice

 

[bleedingthought]

If you can keep your temp constant and around 80, you're fine. Your PH is also fine and is probably lower before your lights come on. HTH