Moyer Diebel Model 201LT heating element failures

Question

I've replaced 3 tank heating elements in my machine in 10 months. The elements have a number of tiny pits and then one breaks thru to the interiorand produces an inch long crack when it shorts out. I'm using Eco Lab products. Eco clean Elite Low temp for cleaning agent and Ultra San, Low Temp Sanitizer. The last Tech measured the chemicals and said the proportion was in the low range for soap & sanitizer use.