I dont know if your problem was the amount of filtration but your media choice. What specific bio ball do you have in the aqua clears ? Also if you want to dedicate the 400 to BIO make sure it has a good pre filter or your setting your self up for one sticky mess and a ammonia spike when you try to clean it. Its best to change the bio media if it comes with crappy media not reengineer the filter. Substrate pro is good im sure some others can put you in the right direction. Unless your tank is cycled then dont mess with the bio.