Please help me protect my African Violets!

I have two indoor windowboxes in my bathroom: one is an open planter, the other is a terrarium with a smaller opening at the top- like a fishbowl. The open planter is infested with thrips, which I am trying to fight (see my other thread); however, in researching thrip extermination, I see that African Violets are terribly succeptible to thrips. The terrarium has African Violets in it, but is not yet infected by its neighbor's problems. Unfortunately, so far I am losing the thrip battle and my open planter looks worse and worse every day. I have read that once thrips devestate their first host, they fly to the next nearest one (including humans!!!!). So my URGENT question is this:

Should I spray my African Violets with pesticide regularly to preemptively avoid thrip infection?

I am planning on going out today after work to buy a stronger thrip fighter (Bayer Rose & Plant 3-in-one, for instance), would this be a good product to pre-treat the violets with? What can I do to protect them from my other planter's terrible fate?

Thank you :*-(

1. What are you treating the thrips with now? Bayer 3/1 is not meant for indoor use, the label specifically says to move plants outdoors before treating. Those chemicals are nothing to joke around it, don't spray them in a confined space.
I recently had thrips on a xanadu philodendron and treated them with my homemade spray.
The spray is a 10oz spray bottle, 10 drops peppermint oil, 10 drops tea tree oil, a squirt of castile(any dishsoap will work) soap, 1/4 cup of rubbing alcohol and water. This has been effective against thrips, aphids and a brown scale

2.I would not recommend spraying the leaves of the violet, they hate being wet. I would move the infested plant to quarantine until you get it under control.

Hello and thank you so very much for your comment. I ended up getting rid of the infested plant all together; and while I did not have the heart to just dump it, I did carry it to the edge of the woods so it could have a fighting chance at survival, at least, without infecting my apartment with bugs (although I am not sure how they got there in the first place). Since then I have replaced the whole thing with a new window box. I am now treating both my African Violets terrarium AND my window box with Bayer, preventatively. It is not a spray, you mix it into water and then just pour it into the soil. The plants absorb the poison/fertilizer and apparently when bugs bite it, they die. It is NOT a spray, so there is no danger of accumilating poisons in my bathroom. You also only treat it every 6 weeks and I use gloves when I do it.

I had to just get rid of the original box because unfortunately even a spray would not have worked- Thrips lay eggs in the soil, so even if I successfully killed the ones on the plant, new ones would be soon to follow.