I tried using it long ago and it was worse soil than MG if you can believe that...
Need more info on the bugs to know anything about what they may be or what to use to kill them. Gnat larvae is my guess and the cheapest way to kill them is to put a layer of sand 1-2" on top of the soil, they can't get through it to repeat breeding and die off fast and will never come back as long as the sand is in place. Then you just water gently as to not mix the sand in, the water will run right through just fine and you can tell when it needs water again by weight rather than other means.