The white "gunk" could be hard water build ups. Not sure though. But in general a vinegar and water mix is what I use to clean up my tanks. Find a sponge that has NEVER had soap anywhere close to it and go to town. Rinse well with fresh water and let the tank sit until you can't smell the vinegar any longer.
Good luck with the angels! Before I got into saltwater I had thought about starting with angels in my freshwater tanks.
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20 High (started 5/18/06)
20 lbs live rock and 3" sand bed - Remora w/ MJ1200 & Prefilter - 10 gallon sump/fuge - MAG7 & SCWD return - 65W 10,000K PC - 15W Actinic - Red-legged Hermits - Cerith Snails - Nassarius Snails - Royal Gramma - 6line Wrasse - Maroon Clown - Wheeler's Goby - Bubble-Tip Anemone - Green Star Polyp - Button Polyps - Frilly Brown Mushroom - Green Bullseye Mushroom - Kenya Tree Coral |