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Originally Posted by Gilraen Took Yup, that's what I got the hornwort for  Thanks. I'd heard that the gravel had to be small for it to be effective. That's cool. |
The gravel in a soil-based aquarium acts as a cap to keep the soil where it should be and out of the water. It also provides a grip for the plants.
Very fine playbox sand makes a great cap, but there are a number of disadvantages to it. Very coarse-grained gravel does not provide a cap. 2mm - 3mm gravel, called "builders sand/gravel" and "blasting sand/gravel" here, is a good compromise. Using it, I've never had the kind of leak that you describe.
"Builders gravel" costs about $7 for 100 pounds here. It needs to be well rinsed.
Bill