1.What are your nitrate readings? You cannot always blame bio balls you have high nitrates do to a lack of denitrification. If you are going to clean your balls as miss Kitty suggests Place some new saltwater in a five gallon plastic bucket, or any other type of good sized deep plastic container. This is where you will rinse and clean the bio-balls off. If you are planning for a water change, water removed from the aquarium may be used for this as well.
2.Turn off the filter.
3.Remove about 1/4 of the bio-balls from the filter chamber and place them into the container with the saltwater.
4.Stir and swish the bio-balls around in the saltwater to break all the gunk or organic matter loose that is stuck on them. If they are extremely dirty, you may have to repeat this step. DO NOT scrub the bio-balls! Just allow the saltwater to do the job, nothing more than that.
5.Scoop the rinsed bio-balls out and place them back into the filter bio-chamber. A plastic kitchen colander works great for this, but any type of cup or small container with drain holes in it will do. The bio-balls come out, the yucky water stays behind.
6.Restart the filter.
7.Test for the appearance of ammonia every few days for a week, then every several days over another week after that. If the testss read near zero after this time, it is ok to repeat the process. If ammonia does appear, wait until readings drop back to zero, then wait another couple of weeks after that before repeating the process with the next batch of bio-balls.
or vist miss Kitty and ask her to clean them for you