Sump Bio Ball Question?

[Mike 1911A1]

I have a 90g AGA with a 15 gal sump. How effective are bio balls if they are submerged? Will they still collect/breed bacteria if under water (like lr) or is it better to leave them above water with water trickling through them?

Mike

 

[artful-dodger]

They will still support some bacteria but not as efficiently without the extra oxygen provided in a drip filter. Definitely leave them above if you have the option.