As a point of clarification, the filter is reading approx 25 psi. That is higher than normal and further impedes the ability of the system to process through enough water volume. Even after hosing off the grid, with a clean grid the system still cannot pull through enough volume to drive the pool cleaner. So this indicates that the grid MIGHT be clogged with scale. That is the recommendation of the pool guy, simply replace the grid even though there are no tears or breaks. My 2nd option is to clean the grid with a scale cleaner such as TSP tri sodium phosphate which is what Pentair suggested. With respect to the pump "bowl or pot" being half full. You think it is debris? I have cleaned the basket strainer and checked for debris but I cannot find any. How would I get a better view of the impellar or system to see if anything is in there causing the problem? Is the debris most likely in the impellar or somewhere else? Maybe one of those Roto-Rooter guys with the camera at the end of the hose might help! Thanks for the guidance so far. BT

One thing I'd recommend doing is taking a few baseline readings on your system. You'll need the water to be pretty clean and clear before you start, but I'd start by opening up the filter and completely cleaning the grids. Seal it back up, set your valves to the "normal" position (make sure to write down how you set the valves), and start up. Take measurements of the system pressure at each of your 4 speeds. This will be your "clean" baseline reading. Now charge the filter with the DE to the recommended amount. (Personally I'd use Zeofiber, it does an even better job and is not as nasty as DE and easier to dispose of) Give the system some time to normalize and evenly coat the filter grids, and take the same readings at each speed. (note, the valves MUST be in the same position for all these pressure readings, and no auxiliary equipment turned on) The reason to do this is so that now you have a recorded value that the system SHOULD be when the filter is clean. If after you backwash and recharge, the pressures are different than this reading, either your backwash was incomplete, the filter is too gummed up to backwash (every now and then you will need to crack it open to wash, backwashing is not perfect), or something else is wrong in the system. Without knowing the baseline figures, it is hard to tell. Now - to determine when the filter is clogged, you'll need to use the max speed like Kelly said, since all the equipment recommendations are based on single speed pumps. (I heard 10psi, but your filter manual should say) Once you reach this amount of pressure above your baseline figure (at 3450, mind you) slow the pump down to each of your three lower speeds and take pressure readings at each case. These are now your "clogged" numbers, and you can use these to determine how dirty your filter is at any operating speed. However at the lower speeds this may only be 1 or 2 psi over "clean" pressure so it might be hard to tell - but at lower speeds the filter can take a bit more clogging so it's not as big a deal as if you were running at full speed. It'll just start absorbing a bit more electrical power until you get the filter cleaned out again, but since you're at low speed already, it's not a lot of power. Hope I didn't confuse you, and hope it helps! Variable speed is awesome, but it can be tricky. Best of luck!

Tell him to look at page 101 of the 2008 catalog. 261050 is an acceptable valve.

First, are these two filters of equivalent size (not actual size)? Generally, a 60 sq-ft DE filter has about the same capacity as a 400 sq-ft cartridge. I know that sometimes the pressure loss does not depend on the filter size so maybe it doesn't matter. If they are comparable in size, then the difference would only be about 10 watts to get to 30 GPM (925 RPM vs 990 RPM). These of course are estimates only and your results may vary. BTW, I have a 420 sq-ft cartrdige filter on a 20k gallon pool and while they are a bit of a pain to clean, I only clean mine every 6 months (no closing) so it isn't so bad. It takes less than an hour to clean the four cartridges. Also, our city requires separation tanks on sand and DE filters which is why I ended going with a cartridge filter. I personally don't have a lot of experience with DE filters but many on this forum and other forums have. One reoccuring theme is that the grids on DE filter occasionally get clogged and require cleaning. From what I understand, this can be a messy job and not too unlike cleaning a cartridge filter. Also, after every backwashing, they require more DE. My point is that DE filters may or may not require less maintenance than a cartridge. No filter is perfect and each has pro and cons. You basically have to pick your poison. Also, what ever type of filter you choose, I would suggest that it is over sized so you don't have to clean it so often and so it cleans better.