Alkalinity Burn (KH Burn)

About this condition

A condition where rapid increases in alkalinity (KH) or excessive dosing damage the growing tips and tissue of corals, causing bleaching and tissue loss. It is especially pronounced in SPS corals, and stable dosing management is the key to prevention.

Common symptoms

• Growing tips (corallite tips) turn white
• Bleaching gradually spreads toward the base
• Polyp extension suddenly worsens
• Tissue thins and the skeleton becomes visible beneath
• Symptoms may appear within hours of dosing

Common causes

• Rapid spike in alkalinity (large addition over a short period)
• Error in dosing concentration or volume
• Incorrect calcium reactor or dosing pump settings
• Sudden parameter shift from a water change
• Quickly raising KH from a low baseline to target values

Prevention (husbandry & daily care)

Make alkalinity adjustments gradually in small increments over time to avoid spikes, and keep values within the target range through regular testing. Having an experienced reefer or specialist review dosing equipment settings is advisable.

Related species guide

When to see a vet

What can a specialist store do?

Consultation with a specialist aquarist or marine aquarium store experienced in coral husbandry is recommended. Presenting records of alkalinity, calcium, and magnesium readings before and after symptoms appeared — along with dosing amounts — helps pinpoint the cause and plan corrective steps. Guidance on gradual parameter adjustment to prevent future spikes and on configuring stable automated dosing systems can be obtained.

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