That's actually a small photo period but by all means not bad. Between my halides and T5's they run 12 hours. You need to look at cyano as a slow battle instead of a quick fix. Don't add red slime remover because it's not fixing the problem at the source. With cyano it's slow and steady wins the race. I've battled it for over a year and I won but there were times that I thought I'm just going to have to get used to it. Blue Green cyano was more difficult than red in my experience. I have a high bioload and I like to feed my fish everyday plus I spot feed our mandarin as well so you can understand why I had high nutrients and cyano. I'm a believer in biopellets and "quality" GFO. I have an over rated skimmer that's for a 180 gallons on the 75 gallon tank. Over time the cyano slowly dissappeared but I also keep an extremely tight maintenance routine with 20% water change every Saturday and i manually removed the cyano during that time. With the types of filtration I'm utilizing it handles the nutrients levels well and exports them efficiently. I'm not saying that if you run biopellets and GFO then you can just dump anything you want into your tank and not worry about maintenance, that would just be ridiculous. There's a balance for every tank and I've found mine and with the filtration I use it keeps my nutrients in check. Just remember, slow and steady.