alkalinity-PH and algae

Question
Hello Michael!
I hope you can help me. I need 5.000 dollars... Just kidding I'm sorry. My tank parameters are: 75G saltwater aquarium, has been set up for reef 5 month ago. 130 lbs of live rocks, approx. 1.5" live sand ( 60 lbs ), 2 anemones (sebea and pink tipped ), 1 colt 1 sun coral,1 spiny oyster and a brown feather duster. I also have 1 brown tang, 1 lawnmower, a pair ( male female ) of yellow stripe maroon clowns, and a flame angel. A 10G wet/dry system with build in protein skimmer 350 G/hr + 2 seio 620 G/hr powerheads  + an 8W rainbow lifegard UV sterilizer. Power compact fluorescent light with 2 65W daylight, and 2 65W actinic bulbs.The light is on about 9 hours/day. I am into saltwater hobby approx. 7 years, but this one is my 1st reef set up. I waited 2.5 month before i introduce the first fish into the tank. All my livestock are very healthy, i had my pink tipped anemone from my previous tank. I have her about 2 years,and she's longer then 1 foot! She's my proud:-) Anyways, let's get the business done. All the test results are great except the alkalinity and PH. NH3, NO2 and NO3 down to 0, the alkalinity is 15-16DKH, while the PH only 8.0. The calcium level is 400-415 ppm, magnesium abou 1350-1380. As i told you all my livestock are in very good shape, all the hair algae died off from the rocks during the curing cycle. I change 10 % of the water every week, using RO water. One of my question is:
When i am mixing the water for the reef tank, should i replace the magnesium, strontium and other trace elements to the water i will drain into the tank? How about the calcium?  I also don't know why is my KH so high, and why can not raise the PH above 8.0 without chemicals? The salinity is 1.024- 1.025. About 2 weeks ago green algae started to grow on my sand, and just getting worse ever since. The algae only shows up on the sand, on the glass it mixes with red and purple coralline algae. I also have some green algae on the rocks, but those are much lighter colors, i think those are some kinda' coralline algae. After water change and vacuum, the algae still coming back. I forgot to mention that the Phosphate levels also 0. Any idea? I can send you a picture if you want me to, and in case you have the time to dealing with my "crap":-) It took me a long time to get up to this level, and i don't want to mess up the project I'm working on. But i bet you know how's that. So if you can help me why is the alkalinity so high, and what could be the cause of the green algae, that would be so great! Your opinion is truly appreciated Michael! Thank you for your time!

Sonny

Answer
Hello sonny
Yes you may have to replace some trace elements when you do water changes. Check them and replace as neccesary.I am trying to figure out your PH problem. How old are your lights? It may be time to change them, they can have an effect on PH.