2Hr Aquarist APT SKY GH Booster & RO Remineraliser

2Hr Aquarist APT SKY – Precision GH Booster & RO Water Remineraliser

2Hr Aquarist APT SKY is a highly concentrated GH booster and aquarium remineraliser developed for planted aquariums, shrimp tanks and aquariums using RO/RODI or naturally soft water.

Unlike conventional remineralisers that may also increase carbonate hardness (KH) or alter pH, APT SKY raises General Hardness (GH) while leaving KH and pH unchanged. This allows aquarists to replenish essential calcium, magnesium and trace minerals while maintaining the soft-water conditions preferred by many aquatic plants and fish.

Precision GH Boost Without Raising KH

One of the key advantages of APT SKY is its ability to increase GH without unnecessarily changing other important water parameters.

It is designed to:

• Increase General Hardness (GH)
• Supply essential Calcium and Magnesium
• Replenish minerals in RO/RODI water
• Leave KH unchanged
• Leave pH unchanged
• Avoid interfering with calibrated NPK fertilizer ratios

This makes APT SKY particularly useful for planted aquariums where precise control over water chemistry and fertilizer dosing is important.

Calcium & Magnesium for Planted Aquariums and Shrimp

RO and RODI water contain very little mineral content and therefore require remineralisation before use in most aquariums.

APT SKY provides 21.5% calcium and 5.4% magnesium, together with trace elements. The manufacturer specifically positions SKY for creating mineral-rich GH conditions while retaining low KH and soft-water characteristics.

This combination can be particularly useful when keeping:

• Caridina shrimp
• Neocaridina shrimp
• Tetras and other soft-water fish
• Soft-water aquatic plants
• Plants that benefit from higher calcium and magnesium availability
• Mixed planted aquariums containing plants with different mineral requirements

Designed for Shrimp Tanks

Calcium availability is particularly important in shrimp aquariums.

APT SKY allows aquarists using acidic aquasoils and RO/RODI water to increase calcium and magnesium availability without simultaneously increasing KH.

According to 2Hr Aquarist, both Caridina and Neocaridina shrimp can benefit from the mineral environment created with SKY, while the low-KH conditions required by many soft-water plants can still be maintained.

APT SKY Dosage

For RO/RODI or soft water, the manufacturer’s baseline recommendation is:

10.5g / 15ml per 60 litres of water.

For precise adjustment:

3.5g / 5ml per 60 litres adds approximately:

12ppm Calcium
3.5ppm Magnesium
+2.5 dGH

If your tap water already contains measurable GH, test the existing GH first and adjust the amount of SKY according to your target hardness rather than automatically using the full baseline dosage.

How to Use APT SKY

APT SKY can be added directly to the aquarium, although adding it to the fresh replacement water during a water change is often more convenient.

The powder can also be mixed with water in a separate container before being added to the aquarium. A temporary milky appearance while the minerals dissolve is normal.

The manufacturer advises that SKY should not be prepared as a highly concentrated stock solution for automatic dosing, because its calcium and magnesium salts require a larger volume of water to dissolve properly.

What GH Should You Target?

The correct GH depends on the aquarium’s livestock, plants and water conditions.

As a general planted-aquarium reference, 2Hr Aquarist notes that many planted tanks perform well at around GH 6.

Rather than relying solely on TDS, use a GH test kit and dose according to the required GH increase. TDS measures total dissolved ions but does not identify which minerals are present, so it is less precise for determining remineraliser dosage.

APT SKY vs APT SKYPLUS

This section is important for both SEO and customers, because Aqua Zones sells both products.

APT SKY

Raises GH only while leaving KH and pH unchanged. It is generally the better choice for planted aquariums, tetras, soft-water plants and aquariums where low KH is desirable.

APT SKYPLUS

Raises GH while also moderately increasing KH to around 2 dKH and buffering pH to approximately 7.2–7.6. It is more appropriate where livestock such as guppies, mollies and snails benefit from additional carbonate hardness.

Both products can be suitable for shrimp; the main difference is whether you want to preserve low KH or deliberately increase it.

Highly Concentrated GH Booster

APT SKY is a concentrated remineraliser. The manufacturer describes it as approximately 3× as concentrated as conventional GH remineralisers.

Because only a relatively small amount is required to produce a measurable GH increase, accurate dosing is recommended, particularly when adjusting water to a specific target hardness.

APT SKY Ingredients

According to the current manufacturer specification:

Available Sizes

2Hr Aquarist APT SKY is available in two sizes:

70gm | 150gm

Select the appropriate size according to your aquarium volume, water-change volume and remineralisation requirements.

Need to increase both GH and KH? Consider 2Hr Aquarist APT SKY Plus which raises GH while moderately increasing KH to around 2 dKH and buffering pH to approximately 7.2–7.6.

Explore more 2Hr Aquarist Planted Aquarium Products available at Aqua Zones.

For the latest dosage guidance, water-parameter recommendations and technical information, visit the official 2Hr Aquarist APT SKY Product Guide.

If you have softwater or use RO water, then simply add 15ml per 60L.

If you have hardwater or are unsure, obtain a GH reading using any common test kit.

Use the SKY Dosage Calculator (below) to determine dosage. For the very first dose, Water Volume = tank’s water volume. GH Reading is your tank’s GH level.

Subsequently, during water change, Water Volume = Volume of new tap water added. GH Reading = tap water GH level.

One way is to first mix APT SKY in a small container with some water and add the milky solution into the tank.

Or you can simply add APT SKY powder directly into the tank. It is OK if it covers the plants.

Use the official APT SKY GH Dosage Calculator to calculate the required amount based on your water volume and current GH