Filter/back washing question

This is not an urgent issue, but last year it was suggested to me that I should only backwash my filter when the pressure rises 5psi above normal (except for algae cleanup or other out-of-ordinary measures). So I never backwashed after about mid-way through last season. After opening yesterday and vacuuming quite a bit of dirt/sediment from the bottom, my filter is still humming along at the usual 14-16psi. I know that it was explained that some dirt actually helps the filter function, and nothing was getting back into the pool from the returns, but I simply don't understand how the filter could take that much dirt without the psi increasing. Any thoughts?

Dirt loads vary tremendously from one pool to the next. Lightly used pools out west commonly run for 3 months with no filter maintenance, so long as there's no overhanging vegetation, and no wind blown dirt. By contrast, moderately used pools in my area -- where bugs, leaves, and thunderstorms abound -- weekly backwashing is more the norm.

That said, I would recommend the DE test -- 2 - 3 cups of DE powder in the skimmer with the pump running -- to check your filter. If no DE comes out into the pool via the returns, your filter is working properly.

And, I'd recommend backwashing at least 3x per season, regardless: 1x on opening; 1x mid-season, and 1x before closing.