Before Hepa, there were Rainbows. Both are good systems..........
I know about both the Hepa filters and Rainbow vacuum cleaners. One
of my first vacuum cleaners was a Rainbow (since I was 9) and now I
have a Hepa filter vacuum. I have had Asthma and allergies all of my
life. I would say that both of you are right to use either of these
vacuum cleaners. Enamel is glass, which is heavier than dust and
most sand particles. That means it will be heavier than water.
Especially when the water is swirling around in a tub as it does in a
Rainbow vacuum cleaner. Rainbows have been out for more years than I
want to admit. They work for most allergy and asthma sufferers. I
think Rainbows are more expensive than today's Hepa filter vacuum
cleaners, which is a more recent technology.
Just thinking about this subject makes me sneeze................ So
use whatever means your logical mind tells you to use. Better to use
any vacuum than no vacuum at all....................... That being
said, if you see dust flying back into the air or "hear" that the
motor on your vacuum isn't performing the way it should, it is time
to get a new vacuum cleaner.
A lot of this will be "common sense".