Buckets instead of dumbbells can certainly exercise biceps brachii, but the weight of buckets is greater than dumbbells. At the same time, because water is a fluid, it will be difficult for you to control the balance on both sides. If you don't do this, your muscles will be sore and it will be difficult to continue. I don't think this kind of exercise will have much effect, if you only make a few bent arms to carry the load and then stop.

In addition, replacing dumbbells with buckets is not a long-term solution. On the one hand, because you are only 16 years old, too much weight-bearing exercise will affect your development. On the other hand, you face the senior high school entrance examination, and you have to deal with writing every day. The pain of biceps will make writing a burden and delay learning.

I have a suggestion. You can use bricks instead of dumbbells. Wrap them in paper first, and then put a thin sponge outside. This can avoid the balance problem in bucket practice and facilitate group practice. At the same time, it will not make the biceps too tired in a short time, and it can also save water.

To tell you the truth, I used to do the same thing. Living in the countryside, people will poke their spine when they buy dumbbells for exercise, and bricks are everywhere.

Your persistence, wish you success!