It probably marginally helps with the efficiency of water flow, but it is a bad idea overall. The negative is that rocks that used to fall away when you turn off the motor now are wedged into the grate. Many happy hours of prying rocks out of the grate with a screwdriver will follow. I know, cause I did it. Never again.
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Jack

Please join CCA. After only 18 months total Pacific Northwest membership is over 7,000. We need you!

The walls of death have got to go!