Effectiveness of Small Refugiums

[tdileo]

I’m curious to see if anyone has studied the effectiveness of NO3 + PO4 export in systems with refugiums that are under the recommended size. I currently have a 90 gallon display, about 105 gallon system total counting displacement, and a refugium of about 5 gallons. My NO3/PO4 is a bit higher than I would like it, and at this point I’m wondering if running the refugium is even worth it, or I’d be better off using the space for a biopellet reactor, GFO reactor, CO2 scrubber, and some other equipment.

 

[Salt1972]

Our refugium is 8-10g on a 125g mixed reef. We use GFO to maintain PO4 at .09 or under. Our nitrates climbed recently to 20ppm. We're not sure why, but we're continuing to watch and monitor. We began dosing iron 3 times per week because it has always seemed to be the limiting factor for caleurpa / chaeto growth in our refugium. Growth has accelerated. We'll see what happens to our NO3 levels.

 

[Gregg @ ADP]

Do you harvest your algae periodically, or let the growth max out and leave it?

 

[tdileo]

Do you harvest your algae periodically, or let the growth max out and leave it?

Harvest of course. Letting it sit can’t do much if anything in the ways of export.

 

[tdileo]

Our refugium is 8-10g on a 125g mixed reef. We use GFO to maintain PO4 at .09 or under. Our nitrates climbed recently to 20ppm. We're not sure why, but we're continuing to watch and monitor. We began dosing iron 3 times per week because it has always seemed to be the limiting factor for caleurpa / chaeto growth in our refugium. Growth has accelerated. We'll see what happens to our NO3 levels.

My nitrates sit steady around 2 and PO4 usually at 0.08, but I’ve seen the PO4 sneak up much higher. I get good growth out of my macros and actually dose a small amount of iron as well

 

[Gregg @ ADP]

Harvest of course. Letting it sit can’t do much if anything in the ways of export.

If you’re regularly harvesting it and still have higher PO4 and NO3, you might have to kick up skimmer usage and/or PO4 export media.

5 gallons isn’t a huge refugium, but it’s big enough to give substantial benefits.

 

[Salt1972]

Do you harvest your algae periodically, or let the growth max out and leave it?

Not sure if you're asking me... We have not harvested. We started with a fist sized bunch of chaeto and didn't get much growth. It didn't recede, but not a lot of growth. (We use a Kessil H80). So, we added a handful of caleurpa. Some growth. We dosed iron for about 2 weeks and both groups took off, over a period of 3-4 months, filled the refugium. Just as we were about to harvest, nutrients bottomed out... .01 PO4 and 1ppm NO3. So, we waited. Over the course of 3-4 months, the refugium receded approx. 50%. We assumed it was starved for nutrients and would achieve a balance. In the middle of this, our Nitrate test kit ran out and when we replaced it, the results were higher. We're not sure if the original test was falsely low or if NO3 increased...

 

[Gregg @ ADP]

My nitrates sit steady around 2 and PO4 usually at 0.08, but I’ve seen the PO4 sneak up much higher. I get good growth out of my macros and actually dose a small amount of iron as well

I wouldn’t worry about your NO3 level...if anything, you might want to bump it up.

PO4 is not ideal, but close enough to get it to where you want it w/o too much work.

 

[Salt1972]

PO4 is not ideal, but close enough to get it to where you want it w/o too much work.

We have to use GFO to maintain PO4 in line with NO3. At one point, PO4 was around .2 while nitrates were running <5ppm. Using GFO in a bag in the overflow, we were able to lower PO4 to .05 and maintain it.

 

[tdileo]

If you’re regularly harvesting it and still have higher PO4 and NO3, you might have to kick up skimmer usage and/or PO4 export media.

5 gallons isn’t a huge refugium, but it’s big enough to give substantial benefits.

Do you definitely think the benefits are that noticeable? I could break down and start a new one easily, but spending a few hundred on reactors and deciding to go back to a refugium would hurt the wallet lol.

 

[ZoWhat]

I’m curious to see if anyone has studied the effectiveness of NO3 + PO4 export in systems with refugiums that are under the recommended size.

I'm telling ya.... if you go to the Chemistry section on R2R and teach yourself how to carbon dose with 50/50 vodka/vinegar....that's all you need.

carbon dosing superchargers good bacteria to overcome bad NO3 PO4 and bad bacteria

my corals are soooooooo much happier since vodka/vinegar dosing a year ago. I have certain SPS thst were nearly dead a year ago that have made a 180deg turn around



.

 

[tdileo]

I'm telling ya.... if you go to the Chemistry section on R2R and teach yourself how to carbon dose with 50/50 vodka/vinegar....that's all you need.

carbon dosing superchargers good bacteria to overcome bad NO3 PO4 and bad bacteria

my corals are soooooooo much happier since vodka/vinegar dosing a year ago. I have certain SPS thst were nearly dead a year ago that have made a 180deg turn around



.

I’ve actually wanted to do a little study into the bacterial growth caused by organic carbon dosing. I know some people that have “ULNS systems” using this method but some filter feeding corals that do poorly for most people seem to thrive. I wonder if the extra bacteria in the water column has anything to do with it, as I’ve read some non-photosynthetic corals filter feed certain species of bacteria.
Beyond that, I currently have no need to drive my nutrients so low but I’ve been considering it just to see how I like the effects on my corals growth and coloration since many SPS keepers seem to do this.

 

[DarkSky]

I have a 220g tank with half of a 75g custom sump as the refugium, filled about halfway with water - so I'd guess I have about a 20g refugium. Along with my skimmer, it keeps my nitrates undetectable, and phosphates below 0.03. I have a sandbed and I've maybe vacuumed it twice. I feed very heavy - acropower, reef chilli, reef roids and several cubes of mysis and pellets daily.

I run a "300w" red LED fixture for 8 hours over the refugium. I harvest about 3 gallons of chaeto every other week.

This has been one of the better export methods I've ever had, honestly.

 

[ZaneTer]

I'm telling ya.... if you go to the Chemistry section on R2R and teach yourself how to carbon dose with 50/50 vodka/vinegar....that's all you need.

carbon dosing superchargers good bacteria to overcome bad NO3 PO4 and bad bacteria

my corals are soooooooo much happier since vodka/vinegar dosing a year ago. I have certain SPS thst were nearly dead a year ago that have made a 180deg turn around



.

That is quite a statement you made there. How exactly does carbon dosing selectively allow “good” bacteria to thrive over bad “bacteria”?

 

[hart24601]

It sounds obvious, but I think this conversation needs to talk about the bioload of the tank when we discuss nutrient exports and the size they require. There is nothing wrong with a smaller fuge if your tank is mostly for coral with just a few fish. I had an sps biocube 14 for years and it only used chaeto in the rear chamber. Of course I had only a couple small fish in there! That chaeto would grow so dense it was amazing though. To the point it was easier to cut then pull out of the media rack and that's no exaggeration.

Now if one wants an ultra fish heavy reef then clearly the export mechanisms need to drastically improve from the above. Reefing has continually pushed stocking density in our systems and people's goals vary so drastically that one person might say "I have a 12" area of chaeto in my 120 that keeps nutrients undetectable" but they only feel a pinch of pellets every day. Another might feed pellets on a timer, multiple frozen cubes, sheets of nori and shrimp/silversides for something like a lionfish and they need carbon dosing, gfo and a huge skimmer. Neither one is wrong. Darksky did bring it up - this is more a rant in general when we discuss export in this hobby, seems like rarely talk about the import especially with beginners!

 

[ca1ore]

My nitrates sit steady around 2 and PO4 usually at 0.08, but I’ve seen the PO4 sneak up much higher. I get good growth out of my macros and actually dose a small amount of iron as well

I’d not judge those levels to be at all problematic (my tank is much higher) unless you’re having pest algae problems. On a space-for-space basis, ATS is better, but only marginally. Whether a 5 gallon refugium is notable for export depends on how much chaeto you harvest.

 

[Belgian Anthias]

Why nitrate may build up in a well lit aquarium with an algae filter not needing any organic carbon and an unlimited energy source? Why nitrate is not used up?
Most probably because all building materials needed for growth can not be provided in time. Or growth is limited by light factors.

What may happen if you start dosing organic carbon in this situation? Where will the building materials come from to support fast bacterial growth?
Dosing carbon to solve a nitrate build up problem will always mess up the reached balance and may remove the installed autotrophic carrying capacity.
A skimmer removes constantly some of the building materials but very selective as mostly apolar and hydrophobic organics are removed. A skimmer will remove max +- 35% of TOC incl DOC leaving 65% mostly polar and hydrophilic organics which may be remineralized and be used by the photo-autotrophs.
As the building materials left are not suitable for most nitrate to be assimilated by the photo-autothrops why should they be suitable to support bacterial growth as they need the same raw materials for growth?

I think kicking up the skimmer ( if possible?) will not bring the solution but doing the opposite will have effect on the assimilation rate if the light intensity is ok.

Very important is the light intensity above the refugium as to much light intensity may slow down the growth due to the fact algae will start to transform the light energy into warmth instead of using it for growth , this to protect there existing cells.

 

[DesertReefT4r]

My little fuge is quite effective. I harvest 80% of the chaeto about every 2 weeks. Sump is a 20L for size ref.

 

[ReeferReefer]

My fuge is only about 2 gallons in my 90g. It helps but I still have nutrient problems. Bigger is better with fuges imo. I still wouldn't run a system without one.