Tempo SC Ultra is not labeled for greenhouse or nursery use.
We would recommend using Talstar P (Talstar One). It is labeled for use in a greenhouse as well as for thrips and various other pests. It is also safe to use on the orchids.
Per the Tempo SC Ultra Product Label: For Mosquito control, when using roughly 5 gallons of water per 1000 sq/ft, you will use 40-80 ml per 25 gallons of water. At the lower rate, this comes out to 800 ml of Tempo per 500 gallon tank.
An alternative product that is one of our top mosquito control insecticide concentrates, that will be typically cheaper per gallon of finished solution would be our Bifen IT. You would use 1.5-3 gallons of Bifen per 200 gallons of water. For your rig you would need at the lower rate, 3.5 gallons of Bifen.