too bad you don't have the other one but since you don't have a choice then this would be ok...better than nothing right? since you are still going through your cycle make sure you add night out 2 every other day to your tank. I guess 3tsp (since you have a 30g) every other day. then refrigerate the bottle after you use it. you can go over with the dosage a little bit...it won't harm your tank.