I wouldn't get too crazy... Many people have small spots of cyano in their tank from time to time. Ive had it on my sand in pretty decent quantities from time to time. Just increase flow on your sand bed if possible, and do some more nutrient export. It should go away on its own. You could also siphon some out every couple of days to speed up the process. Some people also feel it is related to an imbalance in NO3 and P04. Would be worth testing those to see if one is high and the other is 0. Before I did anything drastic, I would be increasing flow first. What you are talking about could cause worse problems, and if the cyano isn't that bad, it might not/probably wont get out of control (depending on nutrient situation and husbandry/flow).