You do it the same way you did the 25% NaOH solution. You will need to determine the density of 48% alum sulfate first.
I did review that answer before I posted , but I don't know how to calculate the solution weight of 25% NaOh or 48% Aluminum Sulfate
Yes. Multiply the weight of a gallon of water by the specific gravity of your wanna be alum solution to get the weight of a gallon of 48% w/w alum sulfate. Multiply that by. 48 and multiply that answer by 8000. That's how much anhydrous aluminum sulfate you will need to use. If you are purchasing the octadecahydrate, multiply that number by the ratio (666/342). If purchasing the hexadecahydrate multiply it by the ratio (648/342).