How many filters are there ...are they available?

There is one filter in the unit. There is the hepa filter and an outer filter to capture large particulate. I vacuum the out filter ever 1-2 weeks to make the filter as a whole last longer. I got my unit in the fall and haven't had to change the filter yet. I'm guesiing it will be 1-2 times a year. When you get a new filter, there are several styles to choose from depending in your need. I filter the air mainly for dust. But you can fet filters that get rid of odors etc. Hope this helped!

Does this have an ionizer.... If so can it be turned off?

ionizers are proven to produce more co2 than any ion "benefit" so stay away from them. this unit has no ionizers and that's why it's great.

True Hepa Filtration is 99.7% however this model states only 99%. Which percentage does it actually filtrate?

Hi Rachel! At this point in time, our machines use a very high-quality HEPA Type material, so they are trapping 99% of particles. We would love to answer all your questions about the differences between the HEPA Type that we use and True HEPA. Feel free to call our Air Quality Experts at 800-630-2396 Option1!