Is the pond aerated?
If it is, then that will do what raking accomplishes. If not aerated, raking will help but for the amount of constant work coupled with the slow noticeable progress, I think the work will most likely be soon abandoned. It would be much better to get the HOA to install aeration. The addition of air (raking the bottom) helps decompose the materials.
Removal of organic material never hurts. When it dies and starts decomposing it helps fuel/start the next round. Granted, it won't eliminate the problems, but it does help if someone is willing to do the work. If possible remove the material to where the decomposed nutrients will not re-enter the pond.
As far as the chemicals and their use, some pro will have to chime in.
