Is a refugium effective at nutrient export? And is there scientific literature to back it up?

[pixelhustler]

I’ve been running a refugium since day one but never found it made much of a difference with nutrient export. It definitely grows pods but I wonder if porous media would do the same. I’m wondering if there’s any scientific literature addressing any of the following questions:

• Any studies comparing tanks with and without refugium, with controlled nutrient inputs.
• Nutrient export comparison between a fuge filled with live rock, and a fuge filled with macroalgae
• Different consumption rates amongst macroalgae species such as caulerpa, different chaetomoropha species (there are more than 50 described), ulva, hair/turf algae, etc.
• Ideal PAR/photoperiod, surface area and water volume in relation to Display tank volume. What size fuge is the sweet spot? And how small is too small to make a difference?
• Impact on the copepod and amphipod population vs inert media. If pods feed on pythoplankton, which is photosynthetic and can therefore grow in the DT, is providing macroalgae/refugium any better than regular housing (inert media).

TL;DR: let’s have an open discussion - does a small-medium refugium make a meaningful difference with nutrient export and micro fauna?

 

[AKG]

Anything that grows faster than a coral is going to be a form of nutrient export, assuming you actually remove it from your tank regularly.

 

[pixelhustler]

Anything that grows faster than a coral is going to be a form of nutrient export, assuming you actually remove it from your tank regularly.

Yes of course. Algae scrubbers have proven this but they are pretty dialed in systems, with very intentional flow rates, growth surface and directed light.

I guess a simpler way to frame my question is:
Would the same volume filled with live rock or similar media outperform a refugium without the need of light or macro harvesting? Both in terms of nutrient export and biodiversity

 

[fish farmer]

I don't run my tank like a science experiment, so take the data as such. I also don't run my chaeto refuge for biodiversity purposes, I use it for algae growth.

I have a 29 gallon DT with a 20 gallon high sump, LPS/softy reef. The tank has been running since around 2010, some of the rock is over 20 years old. I neglected the tank for a while and the tank became a GHA forest where only 5 different softies survived.

I started bringing the tank back to life about 5 years ago, nitrates were around 30 to 40 ppm and phosphates were 1 to 2 ppm (Salifert tests). I used a small 9 watt Feit grow bulb and clip on light fixture over a small section of my 20 gallon sump. I had this over a fist sized piece of chaeto. The chaeto doubled it's size every month and was able to bring down both nitrates and phosphates over several months. It took about a year for them to be very low to not detectable on Salifert kits.

Granted I was doing frequent water changes, siphoning out algae, cutting back feeding, improving skimming.

So the last couple of years my nutrient levels were still running practically undetectable, new LPS additions grew well, softies ran rampant as always. Last year I was waiting for disaster via low nutrients, so I was doing less water changes, dry skimming, feeding about twice as much. Chaeto was hardly growing so I cut back the hours, but still kept a few strands alive.

This summer I started to feed a little bit of reef roids, about half of what was recommended. It shot my nitrates up from 5 ppm to 25 ppm in a month so I stopped doing that. Nitrates were still high the following month so I turned up the hours on the chaeto. The stuff responded well and my nitrates are back down to 2.5 ppm. I never saw a phosphate boost during the reef roid feeding, I assumed that was getting consumed/absorbed quickly by something.

Edit : I forgot to mention that during the lean years I had bought a stronger 20 watt square light which is the current light that is growing chaeto. I have to mounted outside on one side of the sump. I also don't use any grow type additives or add iron.

 

[pixelhustler]

I don't run my tank like a science experiment, so take the data as such. I also don't run my chaeto refuge for biodiversity purposes, I use it for algae growth.

I have a 29 gallon DT with a 20 gallon high sump, LPS/softy reef. The tank has been running since around 2010, some of the rock is over 20 years old. I neglected the tank for a while and the tank became a GHA forest where only 5 different softies survived.

I started bringing the tank back to life about 5 years ago, nitrates were around 30 to 40 ppm and phosphates were 1 to 2 ppm (Salifert tests). I used a small 9 watt Feit grow bulb and clip on light fixture over a small section of my 20 gallon sump. I had this over a fist sized piece of chaeto. The chaeto doubled it's size every month and was able to bring down both nitrates and phosphates over several months. It took about a year for them to be very low to not detectable on Salifert kits.

Granted I was doing frequent water changes, siphoning out algae, cutting back feeding, improving skimming.

So the last couple of years my nutrient levels were still running practically undetectable, new LPS additions grew well, softies ran rampant as always. Last year I was waiting for disaster via low nutrients, so I was doing less water changes, dry skimming, feeding about twice as much. Chaeto was hardly growing so I cut back the hours, but still kept a few strands alive.

This summer I started to feed a little bit of reef roids, about half of what was recommended. It shot my nitrates up from 5 ppm to 25 ppm in a month so I stopped doing that. Nitrates were still high the following month so I turned up the hours on the chaeto. The stuff responded well and my nitrates are back down to 2.5 ppm. I never saw a phosphate boost during the reef roid feeding, I assumed that was getting consumed/absorbed quickly by something.

Edit : I forgot to mention that during the lean years I had bought a stronger 20 watt square light which is the current light that is growing chaeto. I have to mounted outside on one side of the sump. I also don't use any grow type additives or add iron.

Seems like it worked out well for you. My chaeto doesn’t grow much even with long photo periods. I was talking to someone else and they speculated that some strains of chaeto don’t grow nearly as fast - he swears he bought new chaeto and it suddenly started growing quickly. I don’t know if this is true or possible, but there are over 50 species of chaeto described so who knows.

I’m adding live rock to my fuge and I’ll be taking it offline in the next few months. I guess that should answer some of my questions.