I am having trouble keeping my PH above 8 as well as my Alk above 8. Right now calcium is at 440, magnesium is at 1440 and all else is ok with water parameters. What could cause these levels to be so hard to maintain. My tank is about 3 months old. Its a 180 gallon reef tank with 1 blonde naso, 1 yellow tang, 5 bartlett anthias, 2 clowns, 1 yellow head goby and 1 hippo tang.