Comfortis/Spinosad dosage

I am having good luck with Comfortis flea control which contains the
ingredient, Spinosad. This is an organic pesticide derived from a
certain type of fermentation, I believe.

I have many dogs and the tablets are expensive, even when buying
larger doses and splitting accordingly. I have a bottle of Green
Light Lawn & Garden Organic Spray..which is Spinosad (Spinosyn A & D)
0.5% Solution, 16oz for $12.00. I've seen studies that have used
Spinosad in cattle etc.

Wondering if there's anything besides propylene glycol in this
solution it says "other ingredients." Is this something I can use
in place of the Comfortis? How would I figure the equivalent dosage?

Thanks