Hi Jeremy;

+ Do NOT use celluose; it will gum your filter up something awful.
+ For good filtration of fine particles, you need to slow flow down to 45 GPM or less. With an 19 psi filter pressure, you're probably running closer to 65 GPM.
+ Short term solutions: put a valve in between the pump and filter, and throttle the flow till CLEAN filter pressure drops to about 10 psi.
+ Long term, more energy efficient solution: replace the impeller on your pump, with the impeller for an SP2607x10.
+ Long term, MOST energy efficient solution: replace the impeller AND replace the motor with an energy efficient 2-speed model -- and run on low speed except when vacuuming or backwashing.

Sand filters are never the best at small algae particles, but over-driven sand filters are the worst.

Possible quicker cleaner-upper:
1. Make sure your algae is dead (brush the whole pool) and that your FC is > 10 ppm.
2. Turn your pump off overnight. If the algae is settling, add bleach to maintain chlorine, and let it continue settling.
3. If it does not settle, return to filtering.
4. If it does settle, you can vacuum to waste.