Submerged & trcikle filter media

[Brayden's dad]

G'day all,

I'm a little perplexed. I've always been led to believe that de-nitrifying bacteria live only in wet/dry or trickle filter systems. Further, if that media was submerged, then it will (for want of a better term) drown the little fellas.

Now I see media such as Seachem matrix & Eheim Effisubstrat(?) that is recommended to work better when submerged.

So what's the go? Are we talking 2 types of bacteria here? Are we talking one type of bacteria that nobody really knows how it exists?

Troy.

[Ash]

option 2 - same little beasts, lots of mis-information

If bioballs or any other media only worked in a trickle environment then every tank filtered by a HOB or cannister would have ammonia problems.

Whatever the media is, it is only a surface area for bacteria to populate.

[poncho]

My understanding of the denitrifying bacteria is that they won't live in anoxic or anaerobic conditions - which means conditions in the absence of oxygen.

Therefore, you can have denitrifying bacteria in submerged situations as long as the water has dissolved oxygen in it. In a wet/dry trickle system I'm guessing the amount of Oxygen available to bacteria is much more than in a submerged situation and therefore you have more bacteria if Oxygen is the limiting factor.

[canerod]

ditto wot poncho said,

I dont know if there is an anaerobic denitrifying bacteria in fresh water, but there is in marine aquariums, which is why they use a plenum chamber(check spelling)

Bob

[Colfish]

hi Troy

i was always taught that denitrifying bacteria lived in low oxygen levels and darkness

ie; deep sandbed substrate, plenum systems, denitrifying coils etc.

submerged matrix is a good medium for trickle/wet dry systems

on the other hand nitrifying bacteria live in high oxygen levels, emerged bio balls,

course sponge, koi matting etc.

there are two different bacteria at work here, [don't ask me their names, it's getting too late] check FAQ archives

cheers

[Ash]

ahh, I had assumed you were talking about aerobic bacteria?

My understanding is there are two or more aerobic strains that process NH3/4 --> NO2 and then NO2 --> NO3 and one or more strains that in anoxic or anerobic conditions process NO3 to N & O2

Obviously type 1 or 2 can exist in a wet/dry system with bioballs or whatever material for that matter, they also work submerged. The 3rd type will only work in an oxygen depleted environment in the coils/plenum/DSB

From memory the first two are known as nitrosoma & nitrobacter - never heard of a name for the 3rd type.

[GTR73]

Refer the following info on nitrifying bacteria:

(from http://www.2cah.com/netmax/basics/water/water.shtml)

BACTERIA TRIVIA

Ammonia (NH3/4) is converted to nitrite (NO2) by nitrosomonas bacteria. It has been long held that the NO2 eaters, creating nitrates (NO3) were nitrobacter, but some recent research at Marineland points to a species of Nitrospira being responsible, additionally or solely. Using research done at NitroLabs, I've summarized some bacteria characteristics which could be of interest to hobbyists. I've no idea if NitroSpira's characteristics are similar to the NitroBacters, listed below, but then, we are just having a bit of fun with this.

To recap; NH3/4 => Nitrosomonas => NO2 => Nirobacter/spira => NO3.

The last part of the chain (NO3 => anaerobic bacteria => nitrogen gas) is not covered here. The anaerobic bacteria responsible for converting NO3 back into nitrogen gas (to re-enter our food chain) do not have a significant presence in the small ecosystems that our aquariums represent. A bit more on this is in the Filters page discussing biological filtration and filter servicing of sintered glass.

Note that the following characteristic will vary, depending on your setup's characteristics.

optimum growth: 77-86F

growth decreases by 50% @ 64F

growth decreased by 75% @ 46-50F

no activity at 39F

death at 32F or 120F

nitrobacter (makes nitrates) less tolerant of low temperatures

nitrobacter growth, doubles every 13 hours (very slow!)

nitrosomonas (makes nitrites out of ammonia) growth, doubles every 7 hours (slow!)

nitrobacter optimum pH 7.3-7.5 (african's, look out), inhibited at 6.0pH

nitrosomonas optimum pH 7.8-8.0, inhibited at 6.5pH

maximum nitrification rates exist when dissolved oxygen levels exceed 80% saturation, inhibited at 2.0 mg/l (ppm) or less

nitrobacter more strongly affected by loss dissolved oxygen than nitrosomonas

they require micronutrients (not found in RO, distilled or deionised water), most common is phosphorus

nitrobacter cannot oxidize nitrite to nitrate in the absence of phosphates

nitrifying bacteria are photosensitive (bad), esp. to blue & UV light while suspended in the water column

chlorine & chloramines kill nitrifying bacteria

It's not recommended to alter you pH and temperature to accomodate the bacteria, as later you will change back to where you were before, and the bacteria you want are those which like your normal tank parameters. Having said that, optimal bacteria parameters would seem to be, no chlorine or chloramines, 81F, a pH pf 7.4 to 7.9, lots of aeration and having some trace phosphates.

BIOLOGICAL FILTRATION

This is essentially the most important function a filter performs, and it begins with an understanding of the food chain in an aquarium. You feed your fish some fish food. Their solid wastes drop to the bottom and begins decaying releasing ammonia (NH3/4). The fish are also constantly releasing ammonia from their gills. Ammonia is toxic for fish, and cannot be left to accumulate in the water (would burn their gills). Excluding the diluting effects of water changes, or the effects of plants in the aquarium, NH3/4 would be left to build up if it wasn't for the bacteria which consume and convert it to nitrite (NO2). A different species of bacteria then converts the NO2 into nitrates (NO3).

In nature, the NO3 becomes nitrogen gas and returns to the food chain as the fish food you are dropping into the aquarium. In the small highly compressed environment of an aquarium, the food chain essentially ends with NO3 accumulating, which is then diluted through regular water changes. Plants will consume NH3/4, NO2 and NO3 (in that order of preference), and convert it to cellular growth, but it takes a significant amount of plants to match and keep up with a typical fish-load. It is easier to rely on your filter's biological filtration capability.

The bacteria of interest are nitrifying (the process of oxidizing ammonium salts to nitrite and then to nitrates) and aerobic (uses oxygen). They attach themselves to surfaces, making the surface feel slimy (bio-film). The combination of the moving water and the tremendous surface area of the filter sponge makes an aquarium filter an ideal home for bacteria. All filters have a biological capacity, depending on their flow rate (slow is better) and available surface area (bigger is better). Some filters keep the bacteria closer to the air (wet/dry filters and bio-wheels) resulting in a higher density of bacteria.

(note that last paragraph in particular)

cheers

[Ash]

hrm, are they same bacteria active in both salt and fresh water? I'm pretty sure I've read they are.

Lots of reef guys use denitrification, so why haven't these anerobic bacteria been researched more?