Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Ash can make your water BLACK

With all those great reviews, I am sorry to say from my personal experience with this "high grade" carbon.When compared with other carbons by just looking at them (with a very popular carbon that starts with F), this product is pitch black as compared to light grey. Well it is carbon you say, well the other carbon is not as black and doesn't need as much as a gallon of water to get clear. There's so much ash its not even funny.Customer service from the manufacturer is none existent. I wrote an email and no one replied yet.For all the fish owners out there, high quality carbon is with less than 2% ash count. When these real high quality carbons can lower your PH to 6.2 (since they are rinsed with acid to clear the ashes), its something you can fix with a product call PH UP. So high quality carbon and PH UP is a combo you must have when changing carbon.