I switched from a sand filter to a DE filter maybe 20-25 years ago, and one thing you never mentioned is if you had backwashed the filter, and were still seeing 40psi and all that caked on crud. The inside of your filter looks like my Hayward micro-grid DE filter after 1-2 years of no maintenance other than backwashing. Actually, it may look worse.
The routine for me with DE is to backwash for 2-3 minutes, which discharges much of the DE and dirt down the drain, then rinse for about 30 seconds (the ball valve has a position for this). Then back to normal circulate. I tend to backwash when pressure reaches 20psi on the gauge on top of the filter, and then charge with fresh DE. Once a year I will backwash, then break the filter down. Take out the drain plug at the bottom of the filter housing, and hose what you can out that way, then lift off the plumbing and take it all apart. One nut on top holds it all together. Pull each grid off, hose clean, and inspect for damage. Your local pool store may have replacments, but you can also get full sets and individual grids on Amazon.
If you did not see the pool guys take it apart and and mess with it for an hour, leaving old DE all over the grass, then I doubt they did that, and they probably just backwashed the filter...
I procrastinated and never broke it down last year, but am in the middle of moving the filter to a new location, and have a full set of new grids ready to install...
The routine for me with DE is to backwash for 2-3 minutes, which discharges much of the DE and dirt down the drain, then rinse for about 30 seconds (the ball valve has a position for this). Then back to normal circulate. I tend to backwash when pressure reaches 20psi on the gauge on top of the filter, and then charge with fresh DE. Once a year I will backwash, then break the filter down. Take out the drain plug at the bottom of the filter housing, and hose what you can out that way, then lift off the plumbing and take it all apart. One nut on top holds it all together. Pull each grid off, hose clean, and inspect for damage. Your local pool store may have replacments, but you can also get full sets and individual grids on Amazon.
If you did not see the pool guys take it apart and and mess with it for an hour, leaving old DE all over the grass, then I doubt they did that, and they probably just backwashed the filter...
I procrastinated and never broke it down last year, but am in the middle of moving the filter to a new location, and have a full set of new grids ready to install...
