Nitrate levels
 

I bought a 90 gal tank already set up. We used the water he had and 90lbs of live rock. Although we used brand new sand.
Its been up and running for a month and a half and ive been testing quite often. I just found out my test kit for nitrates was way off. the new test kit says my nitrates are about 25ppm. Ive heard this is high so i did a 25% water change and a week later did a 50% water change....
My nitrates still have not come down much and i tested the source water and there is no nitrate level expressed.
How can I get these nitrates down???? I dont over feed but I am also gettin some algae growth on the rocks now...

Water Changes and The best way personnaly is Macro Algea...check your source water for Phosphates!

Likely you had die-off on your rock from the move. Given time it should come down provided you don't have too much livestock in your tank. Your tank will go through a lot of different stages as in establishes itself, I wouldn't worry about it unless it threatens your corals (if you have any). 25 ppm won't hurt anything, but your corals won't "color" nicely at that level.

ok thanks.... whats micro algae and can you buy it?
... Should I have used some of the established sand or was it ok to use all new sand?