Problems with high pH

I have been really battling high pH for the last few months.  I have used the acid buffer to try ot lower, complete multiple water changes, added active carbon, still it might drop but th3e next day it is back up.  Here is a little backgroud as well:  I use tap water (don't shoot me, but I have been doing it for 8 years with no problems, until now)  The tank is newer but used everything from an established tank.  Temp runs between 78-82 for the most part.  I have tried to drop it, but it is just a space problem.  I have been having red algee problems and have been dosing for this as well.  Also, when setting up this tank, I used some sand from a pervious tank I had.  the sand sat for a year in a sealed bucket, and I just trying to rinse it as good as I could.  My tank is a 47g cube and I have about 150-200 lbs of rock (true balancing act as the rock goes to the top of tank)  I have a cpr sump system that skims great and have a korilla 1 for additional circulation.  Also, I am running dual 175MH for 9 hr/day.  Any thoughts?

 

Alos to note, my anenomes have really been mad at me for a while, won't extend. and my green star polys are not extending. my toadstool, finger, hammer,touch are all fine and growing.

 

THe tank itself has been up and going for almost 4 months. All the rock and coral was in a holding tank for about 9 month, but I have had it going in another show tank since 2002. My actual pH has just started to register and I have seen it at 8.0, but most of the itme it shoot to purple instantly which tells me it is above 8.4

 

I don't know what the alk is or how to test it. Yes, you are right that I do have a return pump and add'l one and want to get another one b/c the 47g cube is just akward to rockscape. Do you think that 9a to 6 is too long to keep the lights on?

 

Ph for the tap is 7.8 after the salt is mixed. I have used this same tap water for the past 4 years at this location with minimal problems. This is not saying that rock island hasn't just changed some of its standards. Maybe the current cutbacks meant cutting back on sanitation levels as well. Not a chance, huh?

 

I use my tank as a educational tool for my patients about true balance in life. that is why I am so frustrated with this problem. How can I test for Mag and Alk? I have a couple Kor 3's and a cooling fan on order to try to add current and cool things down to 76-78. All we can do is try.