I have used the same product and while some say its crap, it will at least not harm the tank so no need to do a full water change, just be aware that you cant use this product for three days and then fully stock the tank, use it and add fish food or whatever to get the cycle started and just monitor the chemical levels.
the cloudy water is a part of the process. And just because the water is clear in the 8g does not mean it is cycled.
the cloudy water is a part of the process. And just because the water is clear in the 8g does not mean it is cycled.