Need Help

[Azilla]

For the last 2-3 weeks my tank has been out of control. i get this brown and red stuff all over my sand and rock, I can use a turkey baster and clean it off then next day it looks the same. I was doin a 10Gal water change 1x a week but have been doin 2 lately a week to get rid of this mess. My setup is a 20GAL REEF .....60GAL SUMP.... 20GAL FUGE...
30 Pounds of Sand in main tank and fuge, about 40-50 pound live rock in tank and 5-10 in fuge with little bit of macro. Now i use the baster and clean my tank suck out the sand and blow off the rocks. Then right after i change water. Nothing is working i have a 5 stage RO unit i will get the water tested tomorrow to make sure it is working.

HERE IS A PIC!!
http://www.phatkids.net/sand.jpg