Groomers have ties in the tub that keep the dog in the tub. Your pup might realize he can jump out and be trying to get past you? Also sprayer noise and pressure makes a difference. With the little ones I only use a gentle spray. Also have everything ready so you can go fast.
Sometimes I hate society. spreading lies like that. Its so cool you are a groomer. Maybe you can help me. Why is my dog an angel at the groomer but an absolute demon when I bathe her myself I just don't get it?!