Yeah, the coralline kinda goes with the territory...I think the best refugia benefit from slower water movement into and out of them to allow greater "processing time" for the animals inside to do their magic...
-Scott
Hey Scott, one of the very few times I disagree with you here.... you know how 'Great Minds' so often think alike... lol Will explain it this way, I've seen this written and heard it spoken countless times before on having a slow flow through refugiums to allow time for the Macro or DSB or even Skimmer to process nutrients from the water column and as far as my Biology knowledge goes this is a false statement because Macro Algae and Bacteria both aerobic and anaerobic do not hunt down their food like Lions after Antelope but absorb it through their cellular membrane making water speed (within reason) a non issue. So as for Macro Algae this means the cleaner their surface the better the transfer and why we see the largest concentration of Macro on the reef in the Tidal Splash Zone along the shore or even Back Reef Slope. There are certainly Macro's in the silted Lagoon as well especially the deep rooted Caulerpa family but the healthiest are from much more turbid waters. For the past 20+ years I have ran high-flow to ultra high-flow Sump/Fuge setups in my systems with great success and have kept many species of Macros thriving that would not tolerate slower-flow designs. These systems have also had tremendous populations of Pods, Snails, Worms etc... and even a few baby fish to survive from spawning adults in the DT (recently 6 Bangaii Cardinals). I have approximately 1000+ gph going through my sump/fuge and also run a Hydor K2 for extra flow within the fuge section. Over the years I have seen many problematic systems with slow-flow sumps that are nearly stagnant pools full of Cyano and dying Macro Algae and IMO more of a detriment to the overall system not of any benefit.
Pic below is my sump/fuge setup from yesterday that I took and posted for another thread, not real 'Purdy' but gets the job done... lol
Cheers, Todd