Hi, I have a 90' deep well, 4" diameter, submersible pump at 20+-'. I keep getting sand in my main filter. I do live in a coastal area. I spoke with the well company and they wanted to install a screen for the tune of $600. The bottom of the well was supposedly sealed by local well guy for $200. Is there a screen I can push down past the pump level to resolve this ? Or a screen that attaches to the bottom of the pump? I have not looked at the bottom of the pump, but would this work: http://www.groundwatersupply.net/screencasing.html ?