go with the solar salt. sounds like your blocks got stolen because 3 months sounds too soon to be all gone unless you got lots of rain and used the one pound blocks. thats the problem with using blocks slob hunters and punks will steal them or chuck them somewhere else. the big blocks i think 30lbs i put out in the spring are just about gone only now. im also mixing my solar salt with the rack- up product to give them some minerals and phosphourous. the red trace mineral bricks by themselves werent used nearly as much as the solar salt with the rack- up. maybe because its granular.