Quote:
Originally posted by sabbath
I would like to know this one as well. I have read posts in the filtration forums. That you need larger live rock to break down nitrates. That rubble will not do it. You need the low oxygen area that is deeper into the rock.
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Sorry for this answer is so long in coming---
not necessarily IMO----the rock rubble actually creates a larger surface area.
The rubble in a fuge functions more as a habitat for certain kinds of inverts that you are trying to raise for the main tank.
As far as filtration goes from the refugium chaeto algae will absorb phosphates and nitrates. But you must harvest the chaeto to remove the nitrates and phosphates from the water column otherwise when the chaeto dies they are released back into the water column
This requires an increased flow rate through the refugium
If you are trying to great a larger and more diverse amt of zooplankton then you need to reduce the flow through the refugium to about 1/10 of the main flow.
Live rock, rubble requires less flow to give the bacteria more time to work on the water column
Therefore live rock and rubble are best put in the sump --in a refugium there effeciency in the nitrogen cycle is greatly reduced--either by too much flow or not enough flow/exposure to more of the water column