hi im getting a 90liter tank with a built in filter. Its powerful so i was wondering if i should cover it up somehow so the fish wont get sucked in oh as well will it disrupt my sand on the botom
If the filter was built in to the tank, then it would be designed to have a suitable flow to satisfy your fish. However, if you see your fish struggling to swim then you could try blocking it or connecting a pipe to change the direction of the flow. Most filters will not take up sand so this should not be a problem.