Question about bio cubes

[bbt]

Hi! I have a 250 gallon reef tank, we have a huge bio block in the sump near before the skimmer, but it seems dirty. I think I’m going to get new bio blocks and add them to the section after the skimmer. Is there a recommended area for them?

 

[brandon429]

those are of neutral impact in reefing so it wont matter

if you ran none, your testable params remain the same so place them where most convenient

the reason they're neutral impact is because without them, the reef still controls free ammonia via live rock surface area.