Larger fish create quit a bioload, I would recommend on switching out the bio balls and look to add another filter besides the XP2.
In a wet/dry trickle set up the bio ball allow for lots of oxygen contact which the beneficial bacteria thrives on. In a submerged state this is not the benefit. it a canister filter where the water is forced through the media, the bio balls allow for alot of bypass.
Can you go into more detail please, trying to learn. I can't afford to run 5 or 6 filters. lol
In a wet/dry trickle set up the bio ball allow for lots of oxygen contact which the beneficial bacteria thrives on. In a submerged state this is not the benefit. it a canister filter where the water is forced through the media, the bio balls allow for alot of bypass.