This video shows you the easiest way there is to install substrate without the mess. He's using a 1 liter but I've used 3 liter bottles and even the big iced tea ones like Arizona. The key is to be ready when the bottle empties to cap it off with your hands. This works!
This is by far the easiest and quickest way. Ive done it to all my tanks and never had a problem.
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