Disclosed are methods and compositions of synthesis mixtures for the synthesis of aluminophosphates and silicoaluminophosphate molecular sieves, which enable the control and adjustment of the crystal particle size of aluminophosphates and silicoaluminophosphate molecular sieves. The synthesis mixture compositions used have two or more organic templates present at a molar ratio of total template to aluminum of .ltoreq.1.25; such a synthesis mixture is susceptible to control of product particle size through variation in the amount of seeds used in the synthesis.