Root rot is always a problem so you must use Botanicare HydroGuard or similar. Hypochlorous acid will kill the beneficial microbes in HydroGuard (and everything else) so you cannot use both. Algae is not a problem even when dense, it will consume some of the nitrogen in your nutrient mix. This is not a major concern if you are changing your res once a week as you should be! Shade will prevent algae.
Air circulation can be critical in late flower to prevent bud rot.
You do not mention what stage your plants are in, if young and in veg go for the mycorrhizae if in flower go for the Fan.
Bud Candy added two weeks before harvest will enhance the terpene profile. It is expensive to buy but you only use it once per grow (in my method) so it will last a long time.