.wysiwyg { BACKGROUND: #eff3fa; FONT: 10pt verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; COLOR: #44516a } .wysiwyg A:link { COLOR: #44516a } .wysiwyg_alink { COLOR: #44516a } .wysiwyg A:visited { COLOR: #44516a } .wysiwyg_avisited { COLOR: #44516a } .wysiwyg A:hover { COLOR: #44516a } .wysiwyg A:active { COLOR: #44516a } .wysiwyg_ahover { COLOR: #44516a } P { MARGIN: 0px } .inlineimg { VERTICAL-ALIGN: middle } Hi, just posted a question before because I bought a 150 gallon tank from someone that was established for 7yrs and they had crushed coral. We have been caring for it about a year now and decided to switch to a new 180 gallon tank and add sand instead of the cc. Well I have gotten the nitrates down to 20 by water changes and product called cycle. SOOOO here's my question, there is this awful brown stuff that is on the sand and is coming up on the rock what is it and can I get rid of it?