Hi Lynn! THe good thing with koi clay is, you hardly can overdose with that stuff, and you only need a tiny bit for a tank, the dosage on the container is usually for larger ponds. I usually ad 1 tsp to my 100 gl and above tanks, while doing a bit less for the smaller ones, and 1/2 tsp for the 30 and under. For smaller tanks that package should last you a whole lifetime, and then some!