Just bought a house with an in ground pool - it was a rental before I got it, so you can imagine the (non-existent) maintenance. Working on getting it back to normal - bought a Hayward XL today, the suction was so low on the skimmer that the poor little 'bot just sat there all sad The little "suction test widget" barely moved....
New pump (seller), so that wasn't it. Big Hayward cartridge filter was my next suspect, especially since the gauge was broken. So I installed a new gauge first as a baseline - 22 psi
New filter netted me 14 psi, cleaning the berries out of the new pump basket got me to 10
Happy little 'bot is all over the place now - makes me tired to watch so I guess I'll kick back with a beer and a cigar