I'd personally pass on the chemiclean. It's based on erythromycin and not only goes after Cyanobacteria but it also goes after dentritryifying bacteria as well as other beneficial bacteria in our systems and can lead to increased nitrates as well as other subtle problems. In my experience, there are much better ways to combat cyano that have no detrimental impact on the bacterial bed in our systems.
Cyano tends to accumulate in the areas of our tanks with the least amount of flow. This happens to be the areas of our tanks where waste and solids accumulate and the cyano will feed and flourish in those areas. While Po4 may play a role on it's growth, I've found that Po4 has little impact and cyano can grow even in systems with very low levels or Po4. In my experience, the best way to combat cyano is with increased flow, better husbandry including vacuuming where it accumulates as well as UV filtration. A good UV filter thanks properly setup is the one thing that I have seen first hand that can be very helpful beyond the flow and husbandry that doesn't have a negative impact on the biological bed. The UV can stop the spread of it. It's well documented in water treatment studies that UV filtration is a very useful tool in eliminating cyano bacteria from the water column. Unlike denitrying bacteria in our systems which is relegated mostly to the substrate and rocks in our systems, cyano also is found in the water column. While UV filtration, won't totally eliminate it if there are places where the waste accumulates it will prevent it's spread and can place a huge role in eliminating it.
Places like our refugiums tend to be areas with the least amount of flow and even adding a power head in there my not completely eliminate the issue as there will still be dead spots on top of the chaeto where the power head won't address. We also tend to run lighting in our refugiums that is more conducive to nuisance algae growth. Siphoning the cyano off the top of the chaeto as well as manual removal by hand and turning the chaeto regularly will go a long way to keeping the cyano at bay down there while also promoting better chaeto growth. I run filter socks which help keep my refugium much cleaner and the only algae accumulation I see in there is the stuff commonly referred to as cotton candy algae. I also run a good UV filter that is properly setup and I have seen first hand what UV can do for cyano reduction and elimination. I've been running UV filters on my reef for 20 years and am a big fan of them. Not so much for parasite control but for improved water quality demonstrated by increased ORP, prevention of bacterial blooms, cyano reduction and or prevention as well as a healthier overall system.
