Next week I start shopping for a service to clean my DE filter (Pentair Nautilus FNS48). What would be a reasonable price for someone to come out, disassemble, clean the grids, and reassemble? What if it needs a "chemical treatment" ? How much do those cost? I just want to have my ducks in a row so that I can make the process go a little faster. I live in Pearland (Houston), TX if that matters.