Purple, sand, bubble... Sounds like Cyanobacteria. Increased flow will help, since your levels look good.
Stringy white sounds like spaghetti worms and related microfauna. All fine.
Cut back the lighting an hour or two until the algae is under control. The mushrooms will be fine.
Cleanup crew is not "necessary" but is highly recommended. A combination of small hermits, snails (cerith, Astraea, trochus, nassarius), and bristleworms will handle pretty much anything you throw at them. Start small, just a couple of each. Add more if necessary later.
And relax! You are not alone here. We got your back.