D.E. earth clumping around sides of filter

[pooluser]

When it comes time to clean my DE filter I find most of the DE on the bottom and one side of the filter. Is this normal? I can't figure out why it is not on the grids. Am I doing something wrong? It doesn't seem cost effective.

I pre mix the D.E. earth in a bucket w/water before putting it in skimmer. no matter how slow or fast I put the earth in the skimmer this happens.

Thanks for any assistance.