How to Acclimate Coral Frags | UK Reef Tank Guide

When you buy coral frags online, proper acclimatisation is one of the most important steps to ensure long-term success. Whether you’re new to reef keeping or adding to an established system, learning how to acclimate live corals correctly can prevent coral stress, bleaching, and tissue loss.

This UK reef keeper's guide to coral acclimatisation explains the safest way to introduce coral frags into your aquarium, with tailored advice for soft corals, LPS corals, and SPS corals commonly sold by online coral shops.

Why Coral Acclimatisation Matters When Buying Coral Frags Online

Live coral frags experience unavoidable stress during shipping. Even when shipped overnight within the UK, corals can be exposed to changes in:

• Temperature

• Salinity

• pH

• Oxygen levels

• Light deprivation

• 
  

Sudden changes when placing corals directly into your reef tank can cause coral shock. Proper acclimatisation allows corals to gradually adjust to your aquarium’s water chemistry and lighting conditions, improving survival rates and long-term growth.

This is especially important in UK reef tanks, where room temperatures and seasonal conditions vary significantly throughout the year.

Step 1: Temperature Acclimation for Coral Frags

Before opening the bag:

1. Turn off your aquarium lights.

2. Float the sealed coral bag in your tank or sump for 15–20 minutes.

3. Ensure your tank temperature is stable between 24–26°C.

This step equalises temperature and reduces thermal shock.

Step 2: Drip Acclimation (Best Method for Coral Frags)

Drip acclimation is the safest method for acclimating corals purchased online.

How to Drip Acclimate Coral Frags:

1. Open the bag and transfer the coral and shipping water into a clean container.

2. Use airline tubing to start a siphon from your aquarium.

3. Adjust the drip rate to 2–4 drops per second.

4. Allow the water volume to double over 30–45 minutes.

For sensitive corals (especially SPS), extend acclimation to 60 minutes.

Avoid adding shipping water to your display tank.

Step 3: Coral Dipping Before Placement

Dipping coral frags is strongly recommended before placing them into your reef tank.

Coral dips help remove:

• Flatworms

• Nudibranchs

• Copepods and pests

• Hitchhiking algae

Always follow the manufacturer’s instructions and rinse the coral in clean saltwater before placement.

Acclimating Different Types of Coral Frags

Different corals require slightly different acclimatisation approaches.

Soft Coral Acclimatisation (Zoanthids, Mushrooms, Leather Corals)

Soft corals are generally hardy and beginner-friendly.

Best Practices for Soft Coral Frags:

• Drip acclimate for 30–45 minutes

• Place initially in low to moderate light

• Use gentle to moderate flow

• Expect temporary closing for 1–3 days

Soft corals adapt well to UK reef tanks and are ideal for newer systems.

LPS Coral Acclimatisation (Euphyllia, Acan, Favia, Duncan)

LPS coral frags require greater stability due to their fleshy tissue.

LPS Acclimation Tips:

• Drip acclimate for 45–60 minutes

• Maintain stable alkalinity (7.5–9 dKH)

• Start in lower light and increase gradually

• Avoid strong, direct flow

LPS corals are sensitive to sudden changes and should never be rushed into high-light positions.

SPS Coral Acclimatisation (Acropora, Montipora, Stylophora)

SPS coral frags are best suited for mature, stable reef tanks.

SPS Coral Acclimation Requirements:

• Extended drip acclimation (up to 60 minutes)

• Stable parameters:

  • Salinity: 1.025

  • Temperature: 24–26°C

  • Alkalinity: stable with minimal daily swing

• Gradual lighting acclimation over 1–2 weeks

SPS corals are highly sensitive to alkalinity fluctuations, a common issue in smaller UK reef systems.

Lighting Acclimation for New Coral Frags

Modern LED reef lighting can be extremely intense. Improper lighting acclimation is one of the most common causes of coral loss.

Safe Lighting Introduction Methods:

• Reduce lighting intensity by 20–30% for the first week

• Use built-in light acclimation modes if available

• Place coral frags lower in the tank and raise them gradually

Never place newly purchased coral frags directly under full-power reef lighting.

Common Coral Acclimatisation Mistakes to Avoid

❌ Skipping drip acclimation

❌ Pouring shipping water into your display tank

❌ Placing corals directly under high-PAR lighting

❌ Ignoring alkalinity stability

❌ Adding coral frags to immature reef systems

Patience during acclimatisation dramatically improves coral health.

What to Expect After Coral Placement

It’s normal for newly acclimated corals to:

• Close temporarily

• Look dull for 24–48 hours

• Produce mucus

Avoid moving corals repeatedly. Allow time for adjustment before making changes.

Final Advice for Buying Coral Frags Online in the UK

Successful coral acclimatisation is about slow, controlled adjustment. UK reef keepers should pay particular attention to temperature stability during winter and summer months.

• Soft corals are forgiving

• LPS corals need consistency

• SPS corals demand precision

Following this guide will significantly improve the survival and growth of coral frags purchased from online coral shops.