The bio-balls are really good at collecting aerobic bacteria that turn
ammonia to
nitrite to
nitrate but it stops there. Do you have
LR in your tank? How about sand? Presuming you have them you can start S-L-O-W-L-Y removing the bio-balls, say 10-20% a week. This will allow the bacteria in your sand and rock to catch up with the bioload they now need to handle.
I use an old
wet/dry for my
sump. I have caulerpa in the area that was designed for bio-balls. Below that I have
LR. There is a thin layer of sand under the
LR but it it there by accident, my clown likes to dig and it gets in the water column and ends up in the
sump. I run the outflow from my
skimmer into a 2L bottle to help control bubbles and I have a chaeto ball in there. I really don't have room for a
DSB in mine.