Terrible Advice Tuesdays: The Real Reason Refugiums Fail

Terrible Advice Tuesdays: Filter socks rob refugiums of the nutrients they need to grow.

The rest of the story: Refugiums are a place where algae can grow outside of your display tank. We know algae needs light, carbon dioxide, nitrogen and phosphates to grow. If you placed your filter socks over your refugium light source, then yes, no light would reach your refugium and the algae wouldn’t grow. Filter socks are placed in the sump, not over a refugium light source so that part of this terrible advice can be thrown out.

Carbon dioxide (CO2), nitrogen (N)  and phosphates (PO4) are simple compounds or elements that are much, much, much smaller than even a 1 micron filter socks. Any CO2, N or PO4 in your water column will pass right through a filter sock with ease and feed your refugium.

Should you worry about your refugium not getting the nutrients it needs because you are running filter socks? Clearly not.

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Comments for this article (14)

  • Matt Lowes says:

    Hi Mark,

    Currently using Red Sea NoPox to reduce Nitrates and Phosphates but I am also running RowaPhos in a reactor.

    If I am dosing, should I take my reactor offline considering what I am dosing?

  • al gougler says:

    Hi Mark
    If someone uses Poly Filters, they should check iron in that Poly Filters remove iron and the algae needs iron.

  • JasPR says:

    In a lecture I used to give I began by saying that in all closed systems, ‘things’ build up and ‘things’ are depleted over time.
    As most of you established hobbyists know, a closed box system like 99% of ours are systems on a eutrophication trend line. So even though we think of our aquariums as established living ecosystems- they are really transitory systems- always heading for over-nitrogen rich boxes of pollution. The ONLY question and art then is ” how long and steep” is the trend line!
    One of the very best things we can do to extend the trend line and keep key readings at their desired base line is to keep organic material at a minimum. Use of water changes, socks and pre filter equipment are all examples of ways to suspend the trend line.
    As for ‘starving the refugium’ this depends on what you want ( or think you want). An ecosystem that thrives on nitrogen rich organic laden water is NOT something you what. Those are heterotrophic bacteria species ( often called ‘wolf packs’ by ecology microbiologists) algae forms and molds. NOT desirable!
    In the end, we cannot duplicate the ocean in every detail. Nor do we want the complexity/diversity of the natural ocean. Ours is a science of closed systems. Not to clean– N.T.D. is the goal– ( Not too clean, Not Too Dirty). Spotte said it best– marine culture, a science and an art.

  • Tommy says:

    Hey Mark…congrats on the new little one…
    Trying to work the trifecta (sock, GFO & Carbon reactor chambers and refugium), but I can’t seem to turn the corner.
    The reactor pickup is in the “in” box (after the sock) and it returns to the refugium compartment. There is some bypass directly to the refugium, so I assume there’s enough nutrient bypass to sustain the Chaeto.
    I am continuing to have cyano outbreaks…what gives? I feed only moderately. Can you recommend high quality, low polluting pellets?
    90gal; Yellow Tang, Hippo Tang, clown pair, flame angel, blue damsel, 3-spot domino damsel

  • CN says:

    Thanks JasPR,
    And thanks to my computer’s ability to provide word definition, I now understand this hobby better. What’s happening is that my bank account is on a hypertrophication trend line leading toward suffocation due to excessive addition of “things” that have built up over time. All I have to do from now on is strive for NTDM (Not Too Damn Much) my wife said it best:
    “You don’t need that”

  • Sean says:

    While macro algae won’t be impacted by using socks, what are your thoughts on using socks when the primary purpose of your fuge is to grow pods to feed fish like Dragonets and Copperband Butterflyfish? Would the fuge pods benefit from food particles and other matter that would otherwise be trapped in socks? Whether socks impact the fuge pods or not, I’ve heard some suggest that you’ll be fine without socks if you have good circulation to keep detritus suspended, dose liquid carbon, have strong skimming and run reactors with GAC and GFO? Would you agree?

  • Ron says:

    What 3 things are the most important in a refugiums. set up?

    Small power head any advantage in refugiums?

  • nicholas says:

    The silly thing is if this advice was true, Then why would you want to remove the fillter socks, to let the macro algae grow. It is far easier to manage fillter socks, than it is to manage a refugium. Many people complain they can’t get their algae to grow. If it won’t grow this is good, because you have a low nutrient system. No algae in the refugium, means NO algae in the D.T!!!!.

  • Keith says:

    Hey Mark, i know today subject is on refugiums but a quick question on filter socks. I have had a local fish store tell me to use a 25 micron sock. Do you have any suggestions?

  • John says:

    I used filter sock for years and they keep big items out of the sump. I use 100 micron any smaller will fill up too fast I tried it and not bigger then 200 microns.

  • Keith..25 micron socks will clog very quickly. Use 200 micron socks

  • Pierre Bouic says:

    I have the filter socks but have a direct line from the near surface to the refugium, with a small bit of fine netting to collect food. This supplies the refuge well with half a dozen different types of algae growing. Then my mud box has 2 small lines also from the top of the tank suppling it. The mud box has a series of sponge filters with the water being forced up & thru mud percolating it, with a lot of bio balls & racks under the mud for a large number of surface area for all the hetrotrophic & anerobes to cling to and also macro algae growing on the mud with lights, this is all then directed straight to a pump in the sump which by-passes the filter socks. every month or so I need to trim all types of macro Its not a low nutrient tank, nor a high, but a balanced system as JasPR refers to. My design & build. I’m going to redo the refugium & mud box making al the area’s larger.

  • Nathan says:

    Ok i have a 75 gal Refugium in my basement that is draining into another 70 gal sump system filled with nothing but LR then plumbed to my DT and also a pressure release line coming from my return line back into my refugium i have right now mangroves and other plants with pods, turbos, crabs in my refuge. I did remove my first filter pad, I’m not using socks just a filter pad, so any extra food will feed my refugium tank mates. So far things are working great and not having to do any extra feeding things look very happy. Was that wise and now im just wondering if i should remove the second filter pad so that way any extra food that the first cycle missed will go into the sump and feed the pods in there. Any advise.

  • Michael says:

    I use the KISS approach and it’s working wonderfully. My water drains through a Poly-filter (check them out, they’ve been around since the seventies and still can’t be beat. Next the water flows through four DIY racks made from egg crate and zip ties and filled with Marinepure Spheres and into my protein skimmer, next is the sump spong and out to the return pump. The Poly-filters change colors making it easy to know when to change them. The racks of Marinepure slide in and out making cleaning as easy as swishing each rack around in your waste water. Squeeze out the sponge when changing water & regular maintenance on the protein skimmer and you’ll be golden.

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