FishScience kH Reducer (250ml) – Carbonate Hardness Reducer for Freshwater Aquariums

Getting water chemistry right matters far more for some species than others – and if you're keeping fish that need softer, lower-mineral water, carbonate hardness (kH) is one of the key parameters to get under control. FishScience kH Reducer lowers carbonate hardness gradually and predictably, helping you create the softer water conditions certain species genuinely need to thrive.

Because kH directly influences how stable your pH is, reducing it can also help with pH control – though it needs to be approached carefully and gradually, which is exactly how this product is designed to work. Ideal for aquarists managing precise water chemistry, whether that's for soft water species or general fine-tuning of tank conditions.

Key Features & Benefits

• Reduces Carbonate Hardness (kH): Gradually lowers kH to help create softer water conditions.
• Supports pH Stability: Helps with pH control as part of a considered water chemistry management approach.
• Controlled, Gradual Action: Designed to change water chemistry steadily rather than abruptly, reducing stress on fish.
• Supports Soft Water Species: Ideal for fish that naturally prefer lower mineral content water.
• Suitable for Freshwater Aquariums: Formulated specifically for freshwater set-ups.
• Precise Dosing: Clear dosing guidance allows for accurate, controlled adjustments to water chemistry.

Why We Rate This

Water chemistry products like this one are genuinely for the more experienced end of the fishkeeping hobby – if you're managing a tank for species with specific kH or pH requirements, you already understand why precision matters here. Sudden changes in water chemistry are far more dangerous to fish than the underlying parameter being slightly off, which is why a controlled, gradual-action product is so important.

The dosing guidance is genuinely strict for good reason – never reduce kH by more than 1 per day. Rushing this kind of adjustment is one of the most common mistakes we see, and it can cause far more stress to fish than the original water chemistry issue ever would. Patience and precision are the name of the game with a product like this.

Dosage Guide

Dose 25ml per 100 litres to reduce kH by 2.

Important: Do not reduce kH by more than 1 per day. Always make adjustments gradually and monitor your water parameters closely throughout the process.

Suitable For:

• Freshwater aquariums requiring kH adjustment
• Soft water species that need lower mineral content water
• Aquarists managing precise water chemistry
• Tanks needing gradual, controlled pH stabilisation

Precise water chemistry, properly managed – add FishScience kH Reducer to your basket today.