buy matala bio mats and cut them to the size you need ...these are easy to clean and easy to handle .... just take out the section and spray every so often ... they come in sheets 4'x8'x1.25" and different coarse size ... i use the most dense sheet ... a lot of koi people use them or you can get them in smaller size .. a bit more expensive ... visit your koi shop in the area .. they should have them stocked ... or buy online they are a little cheaper
