Hey reefer, i use bio bizz for soil and asked the same question about using it in a bubbler and was told not to use it as it seperates in water.

The guy at the hydro store recommended Flairforms "Green Dream", been using it about 6 weeks and so far it seems great, (it tells you on the bottle what the ppm or ec should be and also roughly how much in ml's) but there's loads out there you can choose from.

I've had probs with the temp of the bubbler res, hopefully as yours is outside it should be a little cooler, just keep your eye on them, 20-22C is great, anything over 25C and problems start (root rot). You need to keep an eye on your ph too, it can bounce around a bit, when you've done a couple of res changes you'll notice how your ph alters and can tweak it so it stays within range. (i set mine around 5.7 and after 24hours it goes upto 6.2ish)

Good luck!