Wet-Dry = Nitrate Factory?

Discussion in 'Tank Talk' started by MFish, Nov 19, 2006.

  1. MFish

    MFish Pygmy Octopus Registered

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    All along I've been told that wet dry filters are just 'breeding grounds' for nitrates because there is no anaerobic bacteria [since the bioballs/whatever you use] and the aerobic bacteria always has access to the oxygen in the air.

    How have you combated this issue? By filling your wetdry so much that some of the bioballs/biobale/biowhatever is partially underwater?
     
  2. DHyslop

    DHyslop Architeuthis Supporter

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    There are a lot of nooks and crannies in a wet/dry filter that can trap detritus that might otherwise be exported via a filter sock or protein skimmer. That stuff will decompose and add more nitrogen to the system. This can be mitigated very well by filtering the water physically before it enters the wet/dry, and keeping the filter clean.

    There's also a misconception here about aerobic and anaerobic bacteria. The only places in an aquarium where you'll have anaerobic bacteria are deep within rock and deep within a sand bed (4+ inches deep) where water doesn't flow. Anywhere water is flowing will be dominated by aerobic bacteria because, well, your water is oxygenated. A wet/dry filter is extremely effective at turning ammonia to nitrite to nitrate because it is exposed to the air. Submerging part of the filter in water isn't effective because it a) reduces the exposed surface area for those bacteria to grow on and thus actually reduces the amount of filtration capacity and b) does nothing to stop detritus from getting trapped and decomposing, which is what causes excess nitrate in the first place!

    Having anaerobic zones (live rock and deep sand beds) are a good way to reduce nitrates in a reef (the anaerobic bacteria turn nitrate into nitrogen gas), but remember that a tank for a large ceph is a whole different animal. Reefs generally have a lot of this bacteria in the rocks and very little bioload. Reefs tend also to be very stable over long periods of time because corals and small fish grow very slowly and don't generate much waste. Cephs on the other hand grow fast, live hard, and die young: A ceph tank is very "boom and bust" with alternating periods of high and low bioload. The quantity of anaerobic bacteria in LR and a DSB likely won't make a dent in the amount of nitrate you have. Worse, fluctuating nitrate loads probably aren't good for a deep sand bed.

    Dan
     
  3. MFish

    MFish Pygmy Octopus Registered

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    So..basically.. Make sure I have a good pad ontop of the drip plate of my wet dry and I should be fine?

    I'm just so used to building my own refugiums that I never used a wetdry... :X
     
  4. DHyslop

    DHyslop Architeuthis Supporter

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    For a while I was using disposable Marineland filter pads: I could get a big bag of them for $5 and I replaced them once every week.

    Over the last few days I did a major overhaul and found more debris in my wet/dry than I was expecting. Now I've switched to a filter sock, so at my next overhaul in a year I'll take another look in the filter to see if its more effective. I actually have two of them, and after about a week I swap them and soak the dirty one in bleach for a few hours.

    Its also a bit easier to put carbon in the filter sock.

    I want to make sure I don't come across as anti-Berlin. If I was planning a reef I wouldn't dare put a wet/dry on it: its all about having the right tool for the job. I'm a big fan of refugiums and keep one on my octo tank: not so much about 'pods but also a place for more algae in a reverse photo-period. Thanks for the question--I'm writing an article about the nitrogen cycle and filtration to submit to the site and the "nitrate factory" idea is one that had slipped my mind.

    Dan
     
  5. MFish

    MFish Pygmy Octopus Registered

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    I was also planning on incorporating a refugium above the wet dry [small pump in, drain out into the open area, not back over the wet-dry area] for nutrient export with chaetomorpha algae.

    How did you use a filter sock on your wetdry? The space between my input drain, the drip plate, and the bioballs is slim to none.

    Also, thanks for all the input. This is a new experience for me, especially coming from the many different techniques I've used for reefs.
     
  6. DHyslop

    DHyslop Architeuthis Supporter

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    I just made sure there was space between the pipe and the drip plate. My setup is all DIY anyway so it wasn't difficult to plan for it. My wet/dry is a 5 gallon bucket with bulkheads in the bottom, and my drip plate is a plastic pasta strainer.

    Dan
     
  7. Illithid

    Illithid Vampyroteuthis Supporter

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    I put my refugium after the trickle section. I used the output of the skimmer as the pump for input into the refugium, this than overflows to the sump.
    I wasn't getting any debris in the pre filter on the wet/dry so I stopped checking it so often. I used the blue filter matting in a large sheet over the drip plate (rubbermaid tub that has holes drilled in it). I just checked it last week when I noticed the filter sound had a different pitch. I found that the floss had plugged with bacteria that should have been growing on the bioballs (but the floss was first in line :shock: )
    I removed the floss, wrung it out in the sump, and hope all the bacteria will reseat itself on the live rock and bioballs.
    I am now running without any prefilter. I don't like the idea, but I want everything to get stable first.
    I wonder if there are any little inverts that could crawl around the bioballs like mini serpent stars do in the tank. Maybe tiny fiddlers that go in land and water to pick apart anything that happens through the overflow.
     
  8. MFish

    MFish Pygmy Octopus Registered

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    I like the idea of the skimmer dumping into the fuge, and the fuge into the sump portion of the wet dry. Hmm..
     
  9. OoNickoC

    OoNickoC Blue Ring Registered

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    I highly doubt that bacteria were visible, maybe just bi products of thier waste could collect debris......which woould inturn give a sense to thier presence but......they would have to be in a # that would be impossible or near that by almost any home aquarium to be visible. I too have abonded the commone blue/white filter media in lue of micron socks which seem to prove much more durable and you can select the range of size for the collecte dmatter.....in microns nontheless!!!! Pricey but worth the percision and effectiveness imo. The best prefilter I've ever seen is a large, concentrated aiptasia colony in the overflow of a cust.'s tank.
     
  10. OoNickoC

    OoNickoC Blue Ring Registered

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    I highly doubt that bacteria were visible, maybe just bi products of thier waste could collect debris......which woould inturn give a sense to thier presence but......they would have to be in a # that would be impossible or near that by almost any home aquarium to be visible. I too have abonded the commone blue/white filter media in lue of micron socks which seem to prove much more durable and you can select the range of size for the collecte dmatter.....in microns nontheless!!!! Pricey but worth the percision and effectiveness imo. The best prefilter I've ever seen is a large, concentrated aiptasia colony in the overflow of a cust.'s tank. I give a strong "ya" to the filter socks and wed/drys that incorporate them standard.
     
  11. Illithid

    Illithid Vampyroteuthis Supporter

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    The "film" I saw on the media was a uniform light tan in color, and more concentrated where there was higher water flow. There was nothing that was large enough to hold or see on your finger. It did not cling to itself like algae or mold would have and readily fell off the floss when wrung out. It looked like a strained, purified version of what you would find contained in a undergravel filter - so I always figured it was bacteria.

    The tank is 240 gallons with a 90 gallon sump, the filter processes approx. 25 gpm accounting for the bends in piping. The drilled rubbermaid drip plate is approx. 12" x 32" with 1/4 holes drilled throughout. The first chamber in the sump holds 30 gallons of bioballs in 2 stacked rubbermaids that hold 33 gallons each(20 in the first, 10 partially submerged in the second -I got a deal on bioballs :wink: )
    What else could the film be?

    I could easily put on a micron sock, but I have never used one before. What micron size would be optimum for my system?

    The water enters into the system through a single large overflow, using (2) 1 1/2 inch durso standpipes and drains down clear flexible PVC to the top of the drip plate (tub). I could attach the socks to the pipe outlets which are just bulkheads screwed into the tub top (used to make it quieter and stop splashing.)

    Would the socks restrict flow?
    I currently have a thick course sponge block under each bulkhead to quiet it down even more, but they are course enough not to restrict. The water coming down the pipe is just gravity fed (with a little suction form the Dursos) and I don't want the tank to overflow. With the original floss the tank wouldn't overflow, just the drip plate tub, which would overflow to the top of the wet/dry -so no problem.
     

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