Chemi-clean vs cyano one shot wonder ?

[DEAD_BY_DAWN]

The problem is this i look after this guys tank,nice setup big euroreef skimmer plenty of lr low no3 low phosphates etc etc,so last month he got a outbreak of cyano,i tryed Chemi-clean and it worked wonders all gone withing 24hours,but now it's back the tests are all looking good but still it grows,i have redirected the outflows to bast more on the sandbed where othe problem is,it can be found no where other than the sandbed,another shot of Chemi-clean was tryed angd nothing happend well maybe a little dieoff but nothing like it was before,anyone have any thoughts on this matter ..thanks john