5 teaspoons of phosban isn't very much. what is the recommended dose for your tank? it might be helpful to ramp up to more. any GFO will be more effective in a reactor, but failing that the bag should do just fine.
for bubble algae, my best success has been manual removal in conjunction with limiting nutrients. typically during my water changes i would take some dedicated tank tweezers and pluck everything i could, letting it go straight down my siphon hose. i got a 3/8" piece of rigid airline tubing attached to some vinyl hose that is very helpful for that task.
why run the HOB filter if you have a skimmer? any particular reason?
what is your light cycle and feeding regimen like? for the bubble algae i've found it fairly heart in regards to low light conditions, but every little bit helps, and reducing your light cycle may potentially help reduce the cyano as well. along the same lines, what kind of lights are you using? sometimes old bulbs can shift their color temp and help to encourage nuisance algae (if you're using T5/PC/MH).
you may also want to consider increasing the flow in the tank, and blowing out your rocks with a turkey baster on your next water change, and trying to siphon out as much of the detritus as possible that you stir up.
finally, temperature and ambient lighting. i find that my cyano increases in the summer as the tank temperature ticks up with the outside temperature. i also tend to get more early morning sunlight hitting the tank during the summer months, that can also contribute to algae issues.
