I put it in every tank load. Adding lime is no more abrasive than adding granular fertilizer. I have also used my hydroseeder to apply lime and fertilizer to areas that other wise couldnt be reached. Adding lime or granular fertilizer to a hydro seeder will excelerate the wear on your pump, especialy a gear pump machine, unless you are adding massive amounts a centrifical pump will last for a long time. I have a banjo centrifical pump on one of my seeders and the impeller and wear plate along with the seal cost approx $180. to replace. I replace it on adverage of once a year. To extend the live of the impeller and wear plate I made a shim of .040 sheet metal and placed behind the wear plate when it gets worn. This allows me to set the clearance between the impeller and wear plate back to factory specs for almost new performance and extends the lifespan between replacement.