Coral Keeping Guide: Water Parameters and Care

Introduction to Corals

Corals are living animals, not plants. They belong to the phylum Cnidaria and host tiny symbiotic algae called zooxanthellae within their tissues. This partnership allows corals to feed in two ways:

1. Photosynthesis – zooxanthellae convert light into energy for the coral.

2. Direct Feeding – corals capture plankton and organic matter from the water using their tentacles.

Because of this dual feeding strategy, corals require stable water parameters and an environment that balances light, flow, and nutrition.

Ideal Water Parameters for Corals

Advanced Coral Nutrition & Trace Elements

The Role of Amino Acids, Carbohydrates & Vitamins

While zooxanthellae provide much of a coral’s energy through photosynthesis, additional supplementation helps improve coral health, polyp extension, coloration, and growth.

• Amino Acids
  • Building blocks of proteins, essential for tissue repair and skeletal growth.
  • Improve polyp extension, coloration, and resilience to stress.
  • Especially beneficial for SPS corals, which have smaller polyps and higher energy demands.
• Carbohydrates
  • Provide an immediate energy source.
  • Support coral metabolism during times of stress (transport, fragging, parameter swings).
  • Help boost mucus production, which protects corals from pathogens and improves feeding.
• Vitamins
  • Act as co-factors in coral metabolism.
  • Boost immune response and help corals withstand oxidative stress from strong lighting.
  • Vitamin C is particularly important in strengthening tissue health.

Why dose? In a closed reef system, natural food sources are limited. Regular dosing of amino acids, carbohydrates, and vitamins helps replicate the nutrient diversity corals receive in the wild.

Trace Elements & Their Importance

Trace elements are present in natural seawater at very low concentrations but are crucial for coral health, coloration, and growth. In aquariums, they get depleted quickly through coral uptake, skimming, and water changes, so dosing is often necessary.

Key Trace Elements and Their Benefits:

• Manganese (Mn)

  • Role: Co-factor in photosynthetic enzymes; helps energy transfer within coral tissues.

  • Beneficiaries: Particularly important for Goniopora sp. (flowerpot corals).

  • Color Effects: Supports polyp extension and healthy tissue growth.
    

• Potassium (K)

  • Role: Helps regulate osmotic balance, aids in protein synthesis, crucial for skeletal growth.

  • Beneficiaries: SPS corals like Montipora and Acropora.

  • Color Effects: Enhances reds and pinks.
    

• Iodine (I)

  • Role: Boosts soft tissue growth, protects against oxidative stress, enhances mucous production (important for defense).

  • Beneficiaries: Soft corals, gorgonians, and anemones especially rely on iodine.

  • Color Effects: Enhances blue and purple hues, also deepens greens.
    

• Iron (Fe)

  • Role: Essential for chlorophyll synthesis in zooxanthellae, improving photosynthesis efficiency.

  • Beneficiaries: Zooxanthellae-rich corals (SPS & softies), macroalgae in refugiums.

  • Color Effects: Brings out vibrant greens.

• Fluoride (F)

  • Role: Strengthens coral skeleton, improves resistance to pests and stress.

  • Beneficiaries: SPS corals that build dense skeletons.

  • Color Effects: Brings out blue coloration.
    

• Boron (B)

  • Role: Involved in skeletal formation and calcification processes.

  • Beneficiaries: LPS and SPS corals needing strong skeleton growth.

  • Color Effects: Enhances reds and purples.
    

• Bromide (Br)

  • Role: Supports the regulation of zooxanthellae populations and mucous production.

  • Beneficiaries: All corals, especially in nutrient-rich tanks.

  • Color Effects: Indirect — improves overall balance of coloration by regulating algae density in corals.
    

• Strontium (Sr) 

  • Role: Strengthens coral skeleton, improves resistance to pests and stress.

  • Beneficiaries: SPS corals that build dense skeletons.

  • Color Effects: Brings out blue coloration.

• Nickel (Ni)

  • Role: Assists in certain enzymatic processes for zooxanthellae photosynthesis.

  • Beneficiaries: SPS corals in particular.

  • Color Effects: Helps deepen coloration through stronger symbiotic activity.

• Zinc (Zn)

  • Role: Involved in enzyme activity, protein synthesis, and immune defense.

  • Beneficiaries: All corals in trace amounts, especially stressed or recently fragged colonies.

  • Color Effects: Supports overall tissue health and color vibrancy.

• Cobalt (Co)

  • Role: Co-factor for vitamin B12 synthesis, critical for zooxanthellae growth.

  • Beneficiaries: SPS and soft corals alike.

  • Color Effects: Helps maintain natural coral glow

Key Takeaways for Reef Keepers

1. Balance is crucial – Overdosing trace elements can be more harmful than underdosing.

2. Different corals have different needs:

   • Softies → Iodine, Iron

   • LPS → Strontium, Manganese, Boron

   • SPS → Potassium, Fluoride, Iron, Strontium

3. Color tuning with trace elements:

   • Green: Iodine + Iron

   • Blue: Fluoride + Iodine

   • Red/Purple: Potassium + Boron

   • Overall health & polyp extension: Manganese, Zinc, Strontium

Summary

• Amino acids, carbohydrates, and vitamins supplement corals’ diet beyond photosynthesis, strengthening tissue, boosting immunity, and enhancing coloration.
• Trace elements are tiny but mighty—each one plays a specialized role in coral health and color expression.
• For optimal coral keeping, dosing should be balanced and guided by water testing (ICP tests are ideal).

Coral Feeding Guide

Why Feed Corals?

Corals gain energy from two main sources:

1. Photosynthesis – via their symbiotic zooxanthellae algae.
2. Direct Feeding – capturing plankton, dissolved organic matter, and prepared foods.

In the wild, corals benefit from a constant supply of dissolved nutrients and plankton carried by ocean currents. In aquariums, this natural food supply is limited, so targeted feeding ensures they receive the protein, lipids, and carbohydrates needed for optimal health.

Soft Corals (Softies: Leathers, Mushrooms, Zoanthids, Xenia, etc.)

Feeding Style:

• Soft corals rely heavily on photosynthesis but also absorb dissolved organic matter (DOM) and can trap microplankton.
• They don’t have large mouths, so they cannot take in large food particles.

Suitable Foods:

• Phytoplankton (live or preserved) – excellent for filter-feeding softies.
• Marine snow or dissolved organic supplements.
• Amino acid supplements to aid tissue health and pigmentation.

Feeding Tips:

• Broadcast feeding works best: dose liquid phytoplankton or amino acids into the tank.
• Avoid overfeeding, as softies thrive in slightly nutrient-rich water but can trigger algae growth if nutrients spike and bacteria bloom which may decrease pH level. 

LPS Corals (Large Polyp Stony: Euphyllia, Acanthastrea, Trachyphyllia, Lobophyllia, etc.)

Feeding Style:

• LPS corals have large fleshy polyps with visible mouths, designed for capturing and digesting larger prey.
• They are strong feeders and can show dramatic growth with regular supplemental feeding.

Suitable Foods:

• Mysis shrimp (chopped for smaller species).
• Krill, copepods, and enriched brine shrimp.
• Specialized LPS pellets (sinking pellets designed for corals).
• Liquid coral foods containing proteins, fatty acids, and amino acids.

Feeding Tips:

• Target feeding with a turkey baster or pipette is most effective, delivering food directly to the polyp.
• Feed 2–3 times per week for best results.
• Feeding at night often yields better polyp extension (many LPS extend feeding tentacles in darkness).

SPS Corals (Small Polyp Stony: Acropora, Montipora, Stylophora, Pocillopora, etc.)

Feeding Style:

• SPS corals have tiny polyps and rely more on zooxanthellae photosynthesis than direct feeding.
• However, supplemental feeding can greatly enhance growth, color, and resilience in low-nutrient systems.

Suitable Foods:

• Rotifers and copepods (nano-sized zooplankton).
• Coral powders (micro-particulate food designed for SPS).
• Phytoplankton (smaller strains like Nannochloropsis and Isochrysis).
• Amino acids for skeletal growth and pigmentation.

Feeding Tips:

• Use broadcast feeding with fine particle foods 2–3 times per week.
• Ensure strong flow to distribute food evenly but not so strong that polyps cannot capture it.
• SPS benefit from constant low-level feeding rather than large single feedings.

Feeding Balance & Nutrient Control

• Softies: More forgiving, can thrive in nutrient-rich systems.
• LPS: Thrive with moderate nutrients + supplemental feeding.
• SPS: Require low nutrients (nitrate 1–5 ppm, phosphate 0.01–0.05 ppm) but still benefit from targeted micro-feeding.

Key is balance: too little food starves corals, while too much causes algae and cyanobacteria outbreaks.

Summary:

• Softies – mostly photosynthetic, occasional broadcast phytoplankton feeding.
• LPS – big eaters, target feed with meaty foods 2–3x per week.
• SPS – rely on light, but small frequent feedings of micro-foods and amino acids dramatically improve color and growth.

Advanced Coral Feeding Strategies

When to Feed Corals

• Daytime Feeding: Many corals rely on photosynthesis, so their polyps stay partly retracted. However, some soft corals (zoanthids, leathers) respond to broadcast feedings in daylight.
• Nighttime Feeding: Most LPS and SPS extend their polyps fully at night, mimicking wild reef conditions where plankton blooms occur after sunset. Feeding at night increases capture rates significantly.
• Best Practice: Feed 1–2 hours after lights out, when fish are less active (to reduce food theft) and coral feeding tentacles are extended.

Feeding Techniques

1. Broadcast Feeding

• How it works: Add liquid or powdered coral foods directly into high-flow areas.
• Best for: Soft corals, SPS, and filter feeders (gorgonians, feather dusters, clams).
• Pros: Easy and covers entire tank.
• Cons: Less efficient; leftover food can spike nutrients if overused. 

2. Target Feeding

• How it works: Use a pipette or turkey baster to deliver food directly onto coral polyps.
• Best for: LPS corals (e.g., Acanthastrea, Trachyphyllia, Euphyllia) and anemones.
• Pros: Highly efficient, reduces waste, corals show immediate feeding response.
• Cons: More time-consuming in large tanks.

3. Continuous Micro-Feeding

• How it works: Small amounts of coral food (e.g., rotifers, phytoplankton, powdered foods) are dosed several times a day using a dosing pump.
• Best for: SPS-dominant aquariums where stability is key.
• Pros: Mimics natural reef plankton flow, supports sensitive SPS species.
• Cons: Requires dosing system and careful nutrient management.

Natural Feeding Support

1. Refugium Plankton Production
   • A refugium with chaetomorpha macroalgae and live rock can produce copepods, amphipods, and rotifers that drift into the display tank — natural coral snacks.
2. Live Phytoplankton Dosing
   • Regular addition of live phytoplankton supports filter feeders and boosts overall biodiversity.
3. Bacterial Foods
   • Products like Reef Energy AB+ (Red Sea) or Reef Roids are designed to mimic dissolved organic compounds that corals naturally absorb.

Suggested Feeding Schedules

Soft Corals

• 2–3x per week broadcast feeding of phytoplankton or amino acids.
• Supplement with trace elements (iodine, iron) weekly.

LPS Corals

• Target feed 2–3x per week with mysis, krill, or pellets.
• Feed after lights out for maximum polyp extension.

SPS Corals

• Micro-feed daily or every other day with phytoplankton, rotifers, or powdered SPS foods.
• Amino acids 2–3x per week for improved coloration.

Summary:
Corals may survive with only light and stable parameters, but they thrive when fed correctly. By combining broadcast, target, and natural feeding strategies, reef keepers can unlock faster growth, vibrant coloration, and stronger resistance to stress.