water quality presentation with notes
DESCRIPTION
Reef keeping water chemistry presented on 7/19/2014 to CORA by Dick O. and Alex B.TRANSCRIPT
INTRODUCTION TO REEF WATER CHEMISTRY
By:
Alex B.
and
Dick O.
NITROGEN
Main forms of nitrogen we are concerned with include:
• Ammonia (NH3)• Ammonium (NH4
+)
• Nitrite (NO2-)
• Nitrate (NO3-)
NITROGEN – AMMONIA AND AMMONIUM
NITROGEN – USES AND ACCEPTABLE LEVELS
What is nitrogen used for?
• Nucleic acids
• Amino acids proteins
Acceptable levels of nitrogen
Ammonia/Ammonium – < 0.1 ppm
Nitrite – < 0.2 ppm
Nitrate – preferably < 5 pmm
NITROGEN- SOURCES AND PATHWAYS1. Fixation
• Atmospheric nitrogen 78%• Cyanobacteria can fix nitrogen!
2. Mineralization• Decomposition of uneaten fish
food• Fish excretion
3. Nitrification• Ammonium to Nitrite (aerobic)• Nitrite to Nitrate (aerobic)
4. Assimilation• Algae, bacterial, and animal
growth
5. Denitrification• Nitrate into nitrogen (anaerobic,
dissipated through gas exchange)
EXPORTING NITROGEN – CARBON DOSING
Pros:
• Relatively cheap to dose
• Low space requirement
• Can improve coloration of corals
• Also removes phosphorous
Cons:
• Requires a good protein skimmer
• Must watch alkalinity levels
• Dosing can lower pH
• Carbon may promote cyanobacteria
EXPORTING NITROGEN – COIL DENITRATOR
Pros:
• Simple design
• Takes advantage of denitrification bacteria
Cons:
• Requires time for bacteria to colonize
• Must regularly check flow through reactor for changes
• Can get clogged and requires cleaning – resets cycle
EXPORTING NITROGEN – SULFUR DENITRATOR
Pros:
• Can remove large amounts of nitrate
• Media lasts for months
Cons:
• Requires time for bacteria to colonize
• Can lower pH
• Must still maintain water changes to remove sulfates
• Too slow of an effluent rate may release hydrogen sulfide
EXPORTING NITROGEN – MACRO ALGAE
Pros:
• Can help stabilize pH with reversed lighting schedule
• Provides refuge for copepods and other macro-invertebrates
• Also removes phosphorous
Cons:
• Requires regular removal of algae to export nitrogen
EXPORTING NITROGEN – DEEP SAND BED
Pros:
• Simple design
• Takes advantage of denitrification bacteria
• Does not require additional equipment *unless in a remote deep sand bed
Cons:
• Requires time for bacteria to colonize
• Large sand beds can hold lots of detritus, eventually becoming a phosphate source
• Toxic gases can be released if disturbed
EXPORTING NITROGEN – ZEOLITIC MEDIA
Pros:
• Attracts nitrogen ions (NH4+ )
• Can also take advantage of bacteria
• Can create a very low nutrient system
Cons:
• Requires regular dosing of additives
• Media has high affinity for other cations (Ca2+, K+, Mg2+)
EXPORTING NITROGEN – POLYMERS AND SPONGES
Pros:
• Quick acting in case of disasters
• Can absorb both organic and
ionic forms of nitrogen (NH4+
)
(Poly-Filter)
• Some products can be recharged (Purigen)
Cons:
• Media may need replaced frequently depending on bioload
• Purigen only removes organic nitrogen
PHOSPHOROUS
Main forms of ionic phosphorous we are concerned with include:
• Hydrogen phosphate (HPO42-) 79%
• Phosphate (PO43-) 20%
• Dihydrogen phosphate (H2PO4-) 1%
PHOSPHOROUS – USES AND ACCEPTABLE LEVELS
What is phosphorous used for?
• Adenosine Triphosphate (ATP) and other organic compounds
• Phospholipids
• Bones (calcium phosphate)
Acceptable levels of phosphorous
< 0.03 ppm or as low as possible
PHOSPHOROUS – SOURCES AND PATHWAYS
1. Mineralization• Decomposition of uneaten fish
food2. Assimilation
• Algae, bacterial, and animal growth
3. Sorption• Binding of inorganic
phosphorous (Fe, Al, Mn oxides; clays and detritus)
4. Desorption• Release of inorganic phosphate
5. Precipitation• Phosphate falling out of solution
6. Dissolution• Dissolving of soluble phosphate
or introduction via input water (top-off or water change water)
EXPORTING PHOSPHOROUS – OXIDES
Pros:
• Quick acting and highly absorbent
• Some reports of recharging GFO
• May bind some organic phosphate
Cons:
• Media may need replaced frequently depending on feeding
• Some reports of aluminum oxide causing problems with corals
• Can clump up from calcium precipitation
EXPORTING PHOSPHOROUS – BIOLOGICAL CONTROL
Pros:
• Can be relatively inexpensive
• Allows algae and bacteria to do the work for you
Cons:
• Not as quick to export phosphate as other methods
• If using a pro-biotic system, a good protein skimmer is required
• Biota can only consume phosphate if nitrogen is present (Redfield stoichiometry)
Carbon : Nitrogen : Phosphorous 106 : 16 : 1
EXPORTING PHOSPHOROUS – PRECIPITATION
Pros:
• Immediately reacts with phosphorous
• Large amounts of phosphorous can be removed through precipitation
Cons:
• Requires a fine filter removal (5 µm)
• May precipitate carbonates if no phosphate is available
TEMPERATURE
• Appropriate temperature range: 76° F - 81° F (24 – 27°C)
• Lower temperatures can hold more dissolved oxygen
• Higher temperatures can facilitate coral bleaching
PH SALINITY• pH should range from 8.1 - 8.3
• Major source of pH issues is CO2
CO2 + H2O H2CO3
Ways to cure low pH issues:
• Proper aeration can alleviate seasonal low pH issues
• Use an aragonite based substrate
• Dosing calcium hydroxide (kalkwasser)
• Scrubbing the air of CO2 with soda
lime can help with most extreme pH issues
• Appropriate salinity can range from 1.025 to 1.027sg (34-36 ppt)
• Consistency of the desired salinity is most important
• For best results use a calibrated refractometer with an accurate auto top off system.
CALCIUM – USES AND ACCEPTABLE LEVELS
• Main form of calcium we are concerned with: Ca2+
• Calcium is a component of coral skeletons (calcium carbonate) and fish skeletons (calcium phosphate)
• Appropriate calcium range: 380-450 ppm, stability is most important
DOSING CALCIUM – CALCIUM REACTOR
Pros:
• Cheap media lasts for months
• Doses calcium and alkalinity in appropriate proportions
• Can accommodate big systems with large calcium demands
Cons:
• Larger start up cost
• Small adjustments of effluent flow rate may be needed periodically
• Complexity
DOSING CALCIUM – CALCIUM CHLORIDE SOLUTION
Pros:
• Accurate and independent dosing can maintain very consistent results
• Can easily adjust water (tank or water change water) using reef calculators
• Some brands contain other important trace elements (B-Ionic)
Cons:
• Chemicals may become expensive over time with higher calcium demand
• Daily dosing is required for best results
• Will raise salinity over time
DOSING CALCIUM – CALCIUM HYDROXIDE SOLUTIONPros:
• Can assist in keeping pH within desirable ranges
• Also increases alkalinity
• Good for maintaining consistency
• Low start up costs, cheap to maintain
Cons:
• Very alkaline (pH of 12.4) solution can raise pH too fast with quick additions
• Must be dosed in a high flow area to reduce precipitation
• Not ideal for raising calcium by large amounts
• Limited by evaporation
ALKALINITY – USES AND ACCEPTABLE LEVELS
Main forms of alkalinity we are concerned with:
• Carbonate (CO32-)
• Bicarbonate (HCO3-)
• Alkalinity is a component of coral skeleton and helps buffer the water
• Appropriate alkalinity range: 7-11 dKH, stability is most important
DOSING ALKALINITY – CALCIUM REACTOR
Pros:
• Cheap media lasts for months
• Doses calcium and alkalinity in appropriate proportions
• Can accommodate big systems with large calcium demands
Cons:
• Larger start up cost
• Small adjustments of effluent flow rate may be needed periodically
• Complexity
DOSING ALKALINITY – SODIUM BICARBONATE SOLUTION (BAKING SODA)
Pros:
• Accurate and independent dosing can maintain very consistent results
• Can easily adjust water (tank or water change water) using reef calculators
• Most common form of alkalinity in sea water
Cons:
• Chemicals may become expensive over time with higher calcium demand
• Daily dosing is required for best results
• Slight pH lowering effect upon initial dose
DOSING ALKALINITY – SODIUM CARBONATE SOLUTION (SODA ASH)
Pros:
• Accurate and independent dosing can maintain very consistent results
• Can easily adjust water (tank or water change water) using reef calculators
• Helps maintain high pH
Cons:
• Chemicals may become expensive over time with higher calcium demand
• Daily dosing is required for best results
DOSING ALKALINITY – CALCIUM HYDROXIDE SOLUTIONPros:
• Can assist in keeping pH within desirable ranges
• Also increases calcium
• Good for maintaining consistency
• Low start up costs, cheap to maintain
Cons:
• Very alkaline (pH of 12.4) solution can raise pH too fast with quick additions
• Must be dosed in a high flow area to reduce precipitation
• Not ideal for raising alkalinity by large amounts
• Limited by evaporation
MAGNESIUM – USES AND ACCEPTABLE LEVELS
• Main form of magnesium we are concerned with: Mg2+
• Magnesium helps balance calcium and alkalinity by allowing both to co-exist without excessive precipitation
• Magnesium is used in the building of the corals skeleton
• Appropriate magnesium range: 1200-1400 ppm, or 3x your calcium level
Table 1. Magnesium in calcium carbonate skeletons
Organisms
Magnesium content of skeleton (weight %)
Faviid 0.07 - 0.36%
Fungia 0.095-1.22%
Tubiporidae 2.98-3.52%
Porites 0.095-1.22%
Pocillopora 0.34%
Dendrophyllia 0.05%
Coralline algae: Lithophyllum and Lithotamnium
2.0-2.8%
benthic marine Ostracoda (crustaceans)
0.5-1.3%
DOSING MAGNESIUM – CALCIUM MAGNESIUM CARBONATE (DOLOMITE)
Pros:
• Media lasts for months
• Doses magnesium, calcium, and alkalinity
• Can accommodate big systems with large magnesium demands
Cons:
• Must be used in a calcium reactor (larger start up cost)
DOSING MAGNESIUM – MAGNESIUM CHLORIDE AND MAGNESIUM SULFATE
• For best results use a mixture of both with ratios depending on current dosing regime
Pros:
• Accurate and independent dosing can maintain very consistent results
• Can easily adjust water (tank or water change water) using reef calculators
Cons:
• Chemicals may become expensive over time
• Calcium Reactor
• Kalkwasser
• Two-part systems
HELPFUL TIPS AND LINKS
• Reef Chemistry Calculator: http://reef.diesyst.com/chemcalc/chemcalc.html
• DIY Two-part recipes: http://www.reefkeeping.com/issues/2006-02/rhf/
• Remember to always use reverse osmosis de-ionized water!
• Common misunderstanding is 2-part “must” be dosed in equal proportions
REEF PARAMETERSTable 1. Parameters critical to control in
reef aquaria.
Parameter:Reef Aquaria
Recommendation:Calcium 380-450 ppm
Alkalinity
2.5-4 meq/L7-11 dKH
125-200 ppm CaCO3 equivalents
Salinity35 ppt
sg = 1.026Temperature 76-81° F
pH7.8-8.5 OK
8.1-8.3 is betterMagnesium 1200-1400 ppmPhosphate < 0.03 ppmAmmonia <0.1 ppm
Table 2. Other parameters in reef aquaria.
Parameter:Reef Aquaria
Recommendation:
Silica < 2 ppm, much lower if diatoms are a problem
Iodine Control not recommended
Nitrate < 5 ppm
Nitrite < 0.2 ppm typically
Strontium 5-15 ppm
ORP Control not recommended
Boron < 10 ppm
Iron Below Kit Detection Limits (additions OK)
QUESTIONS?