Hey Growmie,
When you are late into flowering the last thing you want to do is use any harmful chemicals or traditional spider mite removal methods.Not sure how you would do it since your growing on your balcony but the suggested thing to do would be:
How to get rid of spider mites during flowering:
Make sure that your grow area is sealed as well as you can, tape any cracks in the windows and doors
Any cracks in the doors & windows will allow oxygen in and defeat the objective, so this is essential.
Set your CO2 meter for 12,000 ppm
If you’re using a grow tent, set the ppm to 15,000 – this will allow for any leaks, If your CO2 meter doesn’t go this high, you can use a calculator.
Calculate the amount of CO2 you will need for your grow space, switch off any exhaust fans.
For example, a 1000 cubic feet grow tent will require 12 cubic feet of CO2, use this calculator for an accurate calculation.
Switch your CO2 generator on and leave the room, if you don’t leave the room at this stage – you’re gonna suffocate and die… so this is pretty important
After your generator has finished pumping in CO2 turn the exhaust fans on before entering the room.
Let the exhaust fans run for at least an hour before entering the room, otherwise, you run the risk of carbon dioxide poisoning.
hopefully, I answered your question and remember ..."Happy Growing" and "Free your mind one puff at a time"