When I first started out, I was using the 8.3 powder, which I mixed up to make a stock solution and was dosing that, it worked just as it said it would. My only issue was, you have to make under the recommended dosage, as anything more and the mix was too saturated and you'd have some undisolved white powder which you'd have to shake/mix once in a while.
Looking back, I'm not sure if it's worth it. You can just bake the bicarb soda and dose Randys for like 10x less.