Mikvah

Question

If a pool is ok to use as a mikvah, what about a bathtub? If it is big, like a jacuzzi, and the woman entirely submerges herself, is this OK? I know this is not the accepted practice but please ask R. Abadi if this is possible. I know at least one woman who absolutely refuses to go to the mikvah even though she is somewhat religious. But she would agree to the jacuzzi with her husband watching.