every year i add about 200# of real salt and a pint of pure lugol's iodine, the fish need this when crowded and the water then aids my gardens.
mh
ps, a secret of growing huge produce is applying sugar to the ground as well as epsom's salts in some cases!!!!!! try adding sugar to tomato plants and see what happens, black strap in cheap 5 gallon buckets is best!!!!!!!!!!!!!