Methods for Filtration in Planted Aquariums

Volume 2, Issue 9 September 2006

Barr Report

Barr Report with Tom Barr and the Plant Guru Team

Special points of interest:

• Feature Article “Methods for “… the bulk of nitrogen Filtration in Planted Aquariums” waste is never trans- formed into nitrate • Circulation, import/ export of waste and (NO3) nor nitrite nutrients, and the (NO2).” loading rate or balance of the system. • Other divalent micro- nutrient cations do not compete with Manganese for other membrane transport sites. Considerable debate in the last 25 years has revolved around filtration of planted aquariums. This is understandable due to the livestock and plant biomass differences hobbyists and aquaculturalist have in their systems as well their expectations. Aquatic macrophytes are used extensively for Inside this issue: wastewater treatment (Reddy et al, 1984, 1989, 1991, 1992). As such, some aquarists forgo any filtration in lieu of the macrophytes being the Feature Article 1 primary filtration component for removal of fish “waste”. Marine aquar- “Methods of Filtration ist routinely utilize refugiums filled with marine macrophytes and deep in Planted Aquari- bed sand beds (DBS’s) for removal of PO4- (phosphate)and NO3- ums” (nitrate) and NH4+.(Ammonium: most is NH3 at these marine pH’s). The Biological Filtration 3 aquarist often removes the mechanical and/or chemical filter entirely. At low fish loads, this appears to work well, although some flow/current is Cycling 4 still required for the best results. This is due to several factors, one being (6) circulation and import/export of waste and nutrients. Another factor is the loading rate of the tank, the “balance”, or, the import load of the Natural Systems 5 system and the means of export. Water changes are not required on systems that have low loading rates as biological processes alone can miti- Chemical Filtration 7 gate the transformations required for export (plant growth/assimilation, bacterial conversions to N2 gas sequestration into the sediments and so Mechanical Filtration 8 forth). No filtration of any kinds is required if large daily water changes are performed also. Some aquarist have done 80% daily water changes

and dosed NH4+ at significantly high levels that would induce algae if Continued on page 2

Barr Report

Methods for Filtration in Planted Aquariums

the water changes where not done. This is one reason why frequent water changes in the initial start up phase is important. Filter bacteria can act as a back up to mitigate NH4+ (ammonium) production from fish waste, leaching and decomposition of plant leaves. These “waste” can induce algae blooms. But what is fish waste? Generally, “plant food”, much like other animal waste; sheep, cattle, chicken manures are used extensively for agriculture for soil enrichment. … Biological filitration is Some addition of inorganic sources can be used to top off the needs of the plants and error in typically the focus of general should be in favor of more plants for the system rather than too many fish to supply the most aquarist..…. plant needs for nutrients. This is primarily due to the production and rapid assimilation (if the system is well designed) of NH4+, and organic nitrogen waste. Both of these (organic nitrogen and inorganic NH4+) have very toxic effects on most all aquatic life and are good algal germina- tors (EPA, 2006; Barr, 2001). Many non carbon enriched planted aquariums require no water changes for many moths and years, the macrophytes effective removing all waste products from the livestock and being exported out as macrophyte biomass. Many non plant aquarists are initially uncomfortable with this filtration concept and lack of water changes, but further investiga- tion clearly shows macrophytes are highly effective at nutrient removal for both fresh and marine aquariums and wastewater treatment systems. Why aquarium manufactures’ have been resistant to produce and market a “plant filter” is still a nagging question in the freshwater hobby, yet the marine aquarist have been utilizing refugiums for many years with very high success rates. Such plant filters can be used for any type of aquarium/closed ecosystem, not just the planted interiors of the tank. Macrophytes can be sold, fed to herbivorous fish, provide cover, export large amounts of waste and have a nice appearance. Bacteria? Chemical media? Water changes? Can any of these be sold and have a nice appearance? The argument for plant filtration is very strong in the hobby. Macrophytes will directly remove ammonia and ammo- “Biolgocial filtration nium (NH3)/ (NH4+) and assimilate these into biomass thereby relieving the loading on the Bio- logical and chemical oxygen demands of a system. The bulk of nitrogen waste is never trans- creates a drain on O2 formed into nitrate (NO3-) nor nitrite (NO2-). levels due to bacteria..” Figure 1 Fig 1 illustrates various forms of nitrogen that may be used and assimilated in plants. As plants can use NO3- and NH4+ (you will note, that there is no NO2- (nitrite) on there). Thus the plant short circuits the bacterial cycling and pre- vents accumulation of

NH4+, NO2- and NO3-. Note: the plant cycle will break down if the plants are not given proper care to grow well. … it is self running to a large degree after a few weeks. Generall the focus is on nitro- (See “free ammonia calculator” below in reference section to read more on this impact on fish). gen waste through bacterial This is not the case to a large degree in terrestrial systems as there is ample oxygen available transformation… the result are and the exchange of gases is 10,000 times more rapid. Nitrogen occurs in natural waters as ni- two chemical ractions which trate (NO3-), nitrite (NO2-), ammonia/ammonium (NH3)/ (NH4+), and organically bound nitro- remove ammonia and oxygen gen. As aquatic plants and animals die, bacteria break down large protein molecules containing from the water. nitrogen into ammonia. Ammonia is then oxidized by specialized bacteria to form nitrites and nitrates. Excessive nitrates and ammonia stimulate growth of algae and other plants, which later

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Methods for Filtration in Planted Aquariums decay and increase biochemical oxygen demand as they decompose.

Filtration is general broken down into three main groups by water engineers:

• Mechanical filtration • Chemical filtration Biological filtration

Biological filtration:

Biological filtration is typically the focus of most aquarist; it is self running to large degree after a few weeks. Gener- ally the focus is on nitrogen waste and the generalized equation for bacterial transformation is: 4 NH3 + 7 O2 => 4 NO2¯ + 6 H2O + energy Note the large oxygen requirement. Now look at nitrite(NO2¯)to nitrate (NO3¯): This is important as plants 2 NO2¯ + O2 = 2 NO3¯ + energy may not yet be geared up to assimilate and take in NO3 Also here again, a drain on O2 levels due to bacteria. The combined result of these two chemi- when nitrate is provided cal reactions is to remove ammonia and oxygen from the water and to produce nitrate and energy. Few aquarium hobby books and nitrogen cycling diagrams make this point very clear and prior to treatments ... the oxygen part of the cycle is typically left out. Ammonia and nitrite are removed from aquarium water in this way, the bacteria need plenty of oxygen in the water. Ammonia is very toxic to fish, nitrite is also toxic but less toxic than ammonia, and nitrate is much less toxic (EPA, 2006). So the beneficial bacteria take oxygen and toxic ammonia from the water and produce rather harmless nitrate and more water. These kinds of beneficial bacteria and lots of oxygen are the crucial factors in eliminating toxic waste and maintaining excellent quality water in an aquarium. Of special note: Timothy Hovanec’s Ph.D. dissertation investigated the bacteria of interest and found that Nitrosococcus oxidized NH4+ to NO2- and Nitrospiro oxidizes NO2- to NO3-, previously the bacteria thought to be responsible where Nitrosomas and Nitrobacter re- spectively. Nitrosomas and Nitrobacter appear to play little role in the cycling of nitrogen in aquariums (Hovanec et al, 1998, 2001).

Generally the Berlin style of wet/dry filter may be used if a sump is a preferred method. A CO2 reactor should replace the protein skimmer, but the overall design with the bag mechnical filter is very good. The wet dry section may still be used, as long as it’s sealed to the outside air to prevent exchange of gases. This removes O2 from the water, and the bacteria use that and give off CO2, so the effect should be similar to that of a canister filter if the overflow section is splash is reduced/minimized. Page 3 Continued on page 4 Barr Report

Methods for Filtration in Planted Aquariums

“… without ample oxygen to supply the bacteria, many aquatic macrophyte systems can become anaerobic

quickly … thus adding Figures 2 and 3. macrophytes can increase the stability of NO3-(nitrate), NO2-(nitrite), NH3/NH4+(ammonia/ the system ...” ammonium) typical cycling time frames in aquariums without plants.

These are two of the better diagrams explaining the cycling, but they still lack the oxygen part of the cycling and it’s very questionable to assume that all aquatic plants remove much NO2-. Although there is a reference for NO2- uptake in Spirodela oligorrhiza, the addition of NH4+ and the subsequent build up of NO2- thereafter and it’s persistence for 2 weeks in new set up aquatic plant tanks lacking the bacteria Nitrospora indicate and suggest that aquatic plants do not use NO2-. NO2- levels do not decline for the 2 week bacterial colonization period. Fishless cycling is widely popular and this pattern of high NO2- persistence for several weeks is widely seen when planted tanks have this cycling method done. This would suggest that most aquatic macrophytes do not use NO2-, rather, it’s a mild toxicant to most macrophytes and very toxic inside the cell. The reference for NO2- uptake also has the “NH4+ adapted” plants being added to the medium with NO2- and NO3-. This is important as the plants have not yet geared up to assimilate and take in NO3- that is inducible uptake (Barr, 2005 => Nitrogen) when nitrate is provided prior to treatments. It would be interesting to see how the Spirodela oligorrhiza responded to the same test when grown prior on a medium containing only NO3- before transfer. Further, the concentration was nearly 133 ppm of NO2- and the concentration of NO3- was nearly 200ppm (Freguson and Bollard, 1969). This fishless cycling method should not be used in a planted tank for multiple reasons (see below)

But are they that crucial in the context of a well planted aquarium?

Compare photosynthesis in terms of oxygen: Carbon Dioxide + Water + Light energy → Glucose + Oxygen + Water 6 CO2 + 12 H2O + ATP + NADPH → C6H12O6 + 6 O2 + 6 H2O

Here, there is oxygen production, rather than a consumption of oxygen in the aquatic ecosystem. Sugar is assimilated, oxygen is produced, not just consumed. This results in a reduction of the biological and chemical oxygen demand (BOD and COD), this results in lower ammonia and ammonium (NH3)/(NH4+). Plants do respire when they use their sugars (glucose), but the net gain is much higher. The aquarist will export these sugars as plant biomass out of the tank also, so the net gain is more oxygen. At night, the plants do not produce oxygen (this occurs only when the light reactions take place) thus the levels of oxygen will decline. This allows more bacteria to respire at maximal rates (higher oxygen levels) than a non planted tank during the day when many fish are most active. Additionally, there is ample organic carbon available for both fungi and bacteria to use for growth in the assimilation of nitrogen (Reddy et al, 2004). Page 4 Continued on page 5 Volume 2, Issue 9

Methods for Filtration in Planted Aquariums

This diurnal pulsing of strong bacterial respiration may reduce the ammonium and increase the decomposition cycling rates of organic detritus. Such cycling will occur at faster rates at warmer temperatures as well (Reay et al, 1999). Both bacteria and algae both assimilated more nitrate as temperature increased from 10 C to 20 and 30 C whereas the assimilation of ammonium remained con- stant throughout the experiment (Reay et al, 1999). This would suggest that macrophytes will use and require more nitrate at warmer optimal temperatures, thus showing dependence on optimal temperatures, whereas the ammonium uptake is independent over a wide range of temperatures.

Without ample oxygen to supply the bacteria, many aquatic macrophyte systems can become anaerobic quickly. This is especially true when the macrophytes are not growing well due to a limitation/s and under another stress. Bacterial respiration and cycling rates are higher in natural system where aquatic macrophyte production is present (Reddy et al, 1998). New aquariums are generally organic carbon limited, thus adding macrophytes can increase the stability of the system and provide faster bacterial growth rates as well as reduced ammonia and ammonium (NH3)/(NH4+) concentrations.

Natural systems:

Aaquatic macrophytes can play an important role in the production processes, nutrient status and oxygen budgets of water bodies (Wetzel and Hough, 1973). Some of the chemical parameters influenced by plants that have been observed to reach lethal limits for common freshwater fish are dissolved oxygen, acidity and ammonia. In some Amazonian floodplain lakes, oxygen concentrations are typically very low and anoxia is frequent, at least in deeper waters where circulation is low. Lago Camaleao in Brazil is located about 15 km above the confluence of the Amazon River as it leads into the Rio Negro. At low water, the lake is dry, apart from a small, muddy pool of 1–2 ha of 50–80 cm depth (Junk et al., 1983) and the dry lake bottom is covered by terrestrial and semi-aquatic or amphibious herbaceous plants, which produce large amounts of organic material. When the water level rises, the lake floods, the terrestrial plants die and decompose, while aquatic plant biomass increases dramatically, with grasses being the most abundant among them. When some of the aquatic plants start dying due to increases in depth/light penetration, about 60% of the lake is still covered by the grass Echinochloa polystachia, and floating plants Eichhornia crassipes and Salvinia auriculata become abundant. Such seasonality and dramatic changes is why many of these plants become weedy when water levels are stabilized in man made lakes and for flood control. They are well adapted to brief periods of suitable habitat and die back naturally due to water level changes. The highest levels of dissolved oxygen have been recorded in the lake when there are still large open water spaces, but low oxygen levels is present when there is a large-scale plant decomposition in progress due to release of organic materials and bacterial decomposition. This may reduce the values at the water surface to 0.5 mg L-1 and even lower below the water surface. An increase in dissolved oxygen concentration is noticed with the reduction in the macrophyte cover which initially may seem counter intuitive. Junk et al. (1983) described the impacts of the low dissolved oxygen concentrations in this lake: fish are forced to expend much energy and time in the search for oxygen, for instance coming to the surface to swallow air, or staying near the surface to use the oxygen-rich surface layer. This may increase the risk of being caught by predators. Food diversity is considerably reduced because phytoplankton and zooplankton become scarce due to high feeding pressures. The bottom fauna is lacking because of the lack of oxygen and is where much of the decomposition by bacteria occurs. A study of numerous shallow lakes in Florida with some macrophytes has shown that leaving a small fringe of vegetation around a lake for the purpose of water quality improvement will have little or no effect on the lake's trophic status (Canfield and Hoyer, 1992). Significantly reducing macrophyte coverage of a lake, for example from 60% to 20% or from 40% to 0% will cause major and observable water quality (water clarity) changes. Conversely, the cover must be raised to 30% to 50% before significant improvement in water clarity will be observable. A similar observation can be made in reference to aquarium plant den- sities. A few macrophytes will have little effect on the system, algae and health, whereas a larger percentage of macrophyte coverage will have much more dramatic impacts.

Within aquatic macrophyte horticulture, the aquarist typically removes the decomposed materials, thus this does not negatively impact oxygen levels in aquariums or ponds if maintained. Aquarist may use “gravel vacuums” to remove excess leaves, particulate organic matter on the surface and within the sediment grains.

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Methods for Filtration in Planted Aquariums Nitrification and organic carbon.

Researchers investigated the effects of organic carbon quantity and quality on nitrification rates in stream sediments. “First, we hypothesized that when environmental C:N ratios are high, heterotrophic bacteria are subject to N limitation and will out compete nitrifying bacteria for available NH4+, thereby reducing nitrification rates. In laboratory experiments, organic carbon amendments (30 mg C/liter, as glucose) to stream sediments completely inhibited nitrification with or without addition of NH4+ (P < 0.0001), whereas amendment with NH4+ only (0.75 mg N/liter) increased nitrification by 40% compared with unamended controls (P < 0.0001). Carbon amendments also increased microbial respiration rates over controls by 4-6 times. Therefore, organic carbon additions significantly decreased nitrification rates but increased total microbial activity. Second, we hypothesized that carbon of high quality would have a stronger negative effect on nitrification than would carbon of low quality. To stream sediments, we added organic carbon as either glucose (higher quality) or sugar maple leaf extract (lower quality). Nitrification rates were reduced by the addition of either organic carbon source but were more severely inhibited by glucose (P = 0.001). Our results suggest that organic carbon is an important regulator of nitrification rates and is of key importance in understanding N dynamics in freshwater ecosys- tems.” (Strauss and Lamberti, 2000).

It has been suggested adding sugar to increase bacterial cycling rates in aquariums, but plants leach a good deal of sugars. Therefore, rather than the view of competing for waste nutrients, it would likely be a better argument that the aquarist view bacteria and plants are complementing each other. Given that other bacteria compete for NH4+ when macrophytes are present at a much more significant rate, and the macrophytes themselves assimilate and take up NH4+ rapidly as well, it stands as a strong comparative argument for both fish health and algal suppression to add macrophytes to an aquarium. Few aquarist have realized that the organic fraction produced by macrophytes will enhance nitrification rates since most aquariums tend to be organic carbon limited, especially in the start up new phase. Adding macrophtyes off sets that and increases both reductions of NH4+ as well increased nitrification, this is a syner- gistic effect to reduce NH4+ to the lowest possible level, rather than to be viewed as bacterial plant competition in the context of algae and water quality. Figure 4 The relation of total nitrogen (sum of total organic nitrogen plus ammonia and nitrite plus nitrate) at Glensboro is similar to that of nitrite plus nitrate because dissolved nitrite plus nitrate constitutes most of the total nitrogen. The median concentrations of organic nitrogen plus ammonia are highest in late summer and early autumn and lowest in late autumn through spring(from the USGS Kentucky Salt Creek water shed data). Here we can view the total individual Nitrogen forms through a season. This type of data is useful for aquariums in terms of algae and plant growth. Algae bloom observa- tions in relation to increases in NH4+ is often noted in such seasonal nitrogen levels.

Fishless cycling in aquatic plant aquariums:

Should an aquarist first cycle their new planted tanks? This is a very common question. Fishless cycling involves adding house- hold ammonia to the aquarium and until the levels of ammonium and nitrite are reduced. The fish are not added unit the after this procedure, generally about 20 days(see figure 1 above), while this can apply to some degree for fish only tanks, NH4+ is used as fast Aquatic weeds up to your as it’s produced and combined with water changes that are com- neck! monly done in planted tanks, ameliorate such waste build ups. Consideration should be made to what the plants utilize in their growth, namely NH4+. The uptake of the primary waste build up

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Methods for Filtration in Planted Aquariums by macrophytes short circuits this process. Macrophytes produce a “silent cycle”. The net result means that there is little reason to worry about ammonium build up to begin with since the macrophytes assimilate it as fast as it’s produced. Some aquarist will sometimes try and take this too far, adding too many fish, over feeding, not performing routine water changes and this will result in an algae bloom. Common sense, good maintenance and reasonable stocking levels should be applied. Macrophytes also possess large amounts of bacteria to seed a new aquarium as well as enhance the growth of nitrifying bacteria (Strauss and Lamberti, 2000). If proper conditions are provided for the macrophytes to grow well, there is no need to worry about cycling such aquariums. Adding seed bacteria from an established tank will also rapidly, rather instantly cycle a new tank. By vacuuming the gravel from an existing planted aquarium, the detritus or “mulm”, may be added to a new aquarium’s gravel bed and filter intake. This adds precisely what is missing in the new aquarium’s gravel and filter bed: bacteria and organic carbon. Adding macrophytes, “mulm” and seasoned filter media allows the aquarist to addressed the cycle and has little need to wait for the three weeks for the tank to cycle the tank. Addi- tionally, many planted aquarist tend to do large frequent water changes, this exports the waste products quickly and these should be done often in the start up phases when using carbon enrichment/fertilization (CO2 gas and/or SeaChem “Excel”). Non carbon enrichment methods are slower growing, lower light in general, and should not use frequent water changes, rather, rely on lower initial fish loads, high plant density and biological processes to stabilize their aquariums. If the aquarist decides to do the fishless cycling, no plants nor lights should be used, as this can lead to green water algae blooms, NH4+ additions and high light are excellent methods to induce green water culture (Barr, 2000). Note:Freuqent water changes can remove any such need for a tank to biologically cycle in terms of ammonium production sense the ammonium is being removed often and large volumes of clean water is replacing it. All filtration does is maintain a lower level of waste in the in term. This is very useful still even with the macrophtyes ammonium removal. Sometimes due to neglect and human error, the macrophytes may not be growing and assimilating optimally and cause a slight back up in the ammonium that might induce algae germination. Such patterns can explain algae outbreaks in many tanks.

Chemical filtration:

Given the efficacy of aquatic macrophytes at waste removal, chemical media is seldom used in planted aquariums (Reddy and Smith, 1989). Zeolite and activated granular carbon maybe used in the initial stages (generally 1-2 months) and later act as biological filtration for bacteria as their chemical binding sites are filled and no longer actively removing waste. These are effective at removal of NH4+ , organics and tan- nins. Activated carbon is a standard protocol for a control with allelopathic chemicals in plant-plant interactions (Callaway and Aschehoug, 2000; Nilsson, 1994 and Ridenour and Callaway, 2001). Activated carbon will remove such organic compounds effectively. As such, it may also be used is a similar fashion with respect to aquatic plants and algae as well. Allelopathy is often discussed in context of algaeóplant interaction, yet there is no evidence to date of this occurring in any aquatic ecosystem nor planted aquarium. Likewise, there is no observed evidence to date in the planted aquarium with over 300 species grown, that allelopathy occurs amongst plantóplant interactions. Such protocols may be of use if an aquarist believes they have found some evidence of an interaction.

Reverse osmosis and ion exchange filtration is sometimes used to soft tap water. Chemical filtration is generally used in conjunction with biological and mechanical filtration methods. Some debate exist with respect to activated carbon and other resins removing trace metals added for plant fertilization. While seldom disputed in theory, practical experiences show that few aquarist have any issues with trace deficiencies when using activated carbon or zeolite. Paradoxically, in many cases, the aquarist see improvements in growth. This may be due to the reduced organic forms of nutrients which tend to be less bioavailable and more towards the inorganic nutrients that provide rapid uptake and assimilation. In slower growth aquariums, this has a less pronounced impact but may play a minor role. In general, most aquarist simply perform water changes to remove such waste as DOC (Dissolved organic carbon) and in/organic forms of NH4+ and NO2-.

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Methods for Filtration in Planted Aquariums

Mechanical filtration:

Particulate and polishing filtration are often used in planted aquariums. Planted aquariums often have good clarity, but many times have high detrital loading. This is sometimes vacuumed away during the water change, but may also be removed via mechanical filtration methods.

Types of mechanical filtration and sterilization commonly used in aquaculture • Sponge filtration: widely used by hobbyists, easy to clean and reused • Floss: good for polishing, clogs rapidly • Diatom: good for polishing water, clogs rapidly • Bag filters: good for micro filtration sizing and high flow rates • Canister: often the preferred choice of aquarist due to low maintenance • Sand filters: undergravel filters fall into this group as do large scale water treatment plants, pond and pool filters • Denitrate filters: sometimes used, but seldom for plant tanks since the plants export the NO3 • Hang on the back aquarium filter: inexpensive and widely used • Bead filters: rarely used in large aquariums • Fluidized bed filters: seldom used in planted aquariums • Ozone and Ultra violet sterilization: UV is often used • Vortex and centrifuge filtration: seldom used

Maintaining low ammonium waste is critical to the health of the fish and livestock population. Below is an illustration that shows what processes lead to fish deaths (Figure 5). Stress comes in many forms, but reduction of stress through better water quality (lower NH4+, higher O2 levels, more cover/hiding locations, more oxygen for the bacteria etc) greatly enhance and contribute to healthier fish. Healthy actively growing plants also = healthy fish. Poorly growing plants on the other hand are a detriment to fish (reduce O2 levels, place a strain on the biological system).

Ammonia is the end product of protein catabolism and is stored in the body of fish in high concentrations relative to basal excretion rates. Ammonia, if allowed to accumulate, is toxic and is converted to less toxic compounds or excreted. Like other weak acids and bases, ammonia is distributed between tissue compartments in relation to transmembrane pH gradi- + ents. NH3 is generally equilibrated between compartments but NH4 is distributed according to pH. Ammonia is eliminated from the blood upon passage through the gills. The mecha- nisms of branchial ammonia excretion vary between different species of fish and different environments, and primarily involves NH3.

Ammonia is toxic to all vertebrates life form causing convulsions, coma and death, probably because elevated displaces K+ and depolarizes neurons, causing activation of NMDA type Figure 5 glutamate receptor, which leads to a rapid influx of excessive Ca2+ and subsequent cell death in the central nervous system. Present ammonia criteria for aquatic systems are typically based on toxicity tests carried out on, starved, resting, non-stressed fish. This is inappropriate for aquariums or field research. During exhaustive exercise and stress, fish increase ammonia production and tend to be more sensitive to external ammonia. Fish have strategies to protect them from the ammonia pulse following large feeding, and this also serves to protect them from increases in external ammonia, as a result starved fish are more sensitive to external ammonia than fed fish. (Randall and Tsui, 2002). Such research suggest that aquarist may not really be provided with the lower levels of ammonium that indicate a healthy environment for their livestock. Past research may be too high in recommendations for acceptable ammonium concentrations. Adding macrophytes that are actively growing and assimilating ammonium may hold more to the health of fish and other livestock than previously consid- ered.

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Methods for Filtration in Planted Aquariums Conclusions: • Aquatic macrophytes enhance the livestock’s resistance to disease and stress

• Reduction in BOD(Biological Oxygen demand) with the usage of macrophytes • Increased reduction of ammonium and nitrite by usage of aquatic macrophytes • Bacteria complement the aquatic macrophytes in the goal of waste removal via assimilation and transformation • Traditional concepts in filter cycling do not apply well or at all in some cases to planted systems • Bacteria use large amounts of oxygen to process waste • Do not use “fishless cycling” with ammonia in planted aquariums

• Nitrosococcus oxidized NH4+ to NO2- and Nitrospiro oxidizes NO2- to NO3-, not Nitrosomas and Nitrobacter • Poorly growing plants decompose, this is worst than no plants at all in a system, Learn to grow the plants well!

• Good filtration and plant growth will defend well against algae blooms as ammonium is an excellent germinating agent for algal spores. • Higher temperatures increase nitrate uptake relative to ammonium. • Higher temperatures place more demand on oxygen, decomposers and livestock due to faster growth demands, as well as less gas in solution at saturation (all gases).

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Hovanec, T. A., L. L. Wilson, Jr., J. Niemans, J. L. Coshland, S. Wirtz and J. R. Sears-Hartley. 2001. A comparison of four types of coral reef filtration systems: preliminary results p. 45-52. In C. M. Brown and L. Young (ed)., Proceeding of the Marine Ornamentals '99. UNIHI-SEAGRANT-CP-00-04. Univ, Hawaii Sea Grant. Hovanec, T. A. L. T. Taylor, A. Blakis and E. F. DeLong. 1998. Nitrospira-like bacteria associated with nitrite oxidation in freshwater aquaria. Applied and Environmental Microbiology 64(1): 258-264.

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Web references: http://fins.actwin.com/aquatic-plants/month.9507/msg00139.html

Free ammonia calculator: http://cobweb.ecn.purdue.edu/~piwc/w3-research/free-ammonia/nh3.html

Allelopathy methods: activated carbon http://www.regional.org.au/au/allelopathy/2005/2/6/2412_weidenhamerjd.htm

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