If you do, it won't be because of the filter.
Do you have any Epsom salt? Mix two level tea spoons into some aquarium water and then add to the fish tank. I would recommend doing a 50% w/c just before adding the salt. If you do a water change, make sure to use a dechlorinator.
Please go and have your water tested at the fish shop, then write down all the results, I have a bad feeling that you might have a lot of ammonia and nitrite in your tank.
Do you have any Epsom salt? Mix two level tea spoons into some aquarium water and then add to the fish tank. I would recommend doing a 50% w/c just before adding the salt. If you do a water change, make sure to use a dechlorinator.
Please go and have your water tested at the fish shop, then write down all the results, I have a bad feeling that you might have a lot of ammonia and nitrite in your tank.