When I used to pour my water in to quickly and get all the gunk up from the bottom of my tank I would just stick the net in and move it around and catch it all up I the net. I now pour my water in slower and don't get any gunk coming up. I was also told I could use a small jug, pour it over the back of my hand or onto a big ornament to disrupt the flow so that it does not disturb the substrate. I have not tried any off those 3 as I found pouring the water in slower makes sure that none of the gunk comes up from Tom