APT - SKY For RO Remineralizer, Good for shrimp health in softwater and good for hardwater and softwater plants

Quick Answer

2Hr Aquarist APT SKY is a concentrated GH booster and remineraliser designed primarily for RO/RODI water and naturally soft water.

It replenishes important minerals—especially calcium and magnesium—while raising General Hardness (GH) without increasing KH or changing pH.

APT SKY is particularly useful for:

• Planted aquariums using RO/RODI water

• Soft-water aquascapes

• Shrimp tanks

• Aquariums where additional calcium and magnesium are required

• Hobbyists who want to increase GH while keeping KH low

APT SKY is not medication and does not treat fish disease.

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Product Overview

RO and RODI water contain very little mineral content. While this gives aquarists greater control over water chemistry, important minerals must usually be added back before the water is suitable for aquarium use.

APT SKY is designed specifically for this purpose.

It increases General Hardness (GH) by supplying calcium, magnesium and trace minerals while avoiding significant changes to:

• KH (Carbonate Hardness)

• pH

• NPK nutrient levels

This makes it particularly useful in planted aquariums where aquarists want sufficient mineral availability for livestock and plants while maintaining soft, low-KH water conditions.

At the manufacturer's reference dosage:

3.5 g / 5 ml per 60 L
adds approximately:

• 12 ppm Calcium

• 3.5 ppm Magnesium

• +2.5 dGH

The manufacturer's recommended baseline dosage for RO/RODI water is:

10.5 g / 15 ml per 60 L

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Who Is This For?

APT SKY is especially suitable for:

• RO/RODI water users

• Aquarists with naturally soft tap water

• Planted aquarium hobbyists

• Aquascapers

• Freshwater shrimp keepers

• Caridina shrimp setups

• Neocaridina shrimp kept in suitable soft-water setups

• Soft-water community aquariums

• Aquariums containing plants that prefer low KH

• Hobbyists who need to increase GH without deliberately increasing KH

Particularly useful when:

• Your source water has very low GH

• You use RO/RODI water for water changes

• Your aquarium needs more calcium and magnesium

• You want to maintain low KH for sensitive plants or soft-water fish

• You want better control over aquarium mineral levels

You may not need APT SKY if:

Your tap water already has sufficient GH for your livestock and plants.

Always test your source water before adding a remineraliser simply because the aquarium contains shrimp or plants.

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Variant Guide

APT SKY – 150 g

Best for: Small to medium aquariums, first-time users and hobby tanks.

Same standard APT SKY formulation in a smaller pack.

Raises GH only while leaving KH and pH essentially unchanged.

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APT SKY – 800 g

Best for: Larger aquariums, multiple tanks or regular RO/RODI users.

Same APT SKY formula as the 150 g pack, in a more economical larger size.

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APT SKY+ – 150 g

Important: SKY+ is a different formula, not simply another pack size.

APT SKY+ increases GH and also raises KH moderately, while buffering pH.

Choose between them according to the water chemistry you want:

APT SKY

• Raises GH

• Leaves KH unchanged

• Leaves pH unchanged

• Better suited to soft-water planted tanks and soft-water fish

APT SKY+

• Raises GH

• Raises KH to approximately 2 dKH

• Buffers pH approximately 7.2–7.6

• More suitable where livestock benefits from some carbonate hardness

The manufacturer specifically suggests SKY+ for guppies, mollies and snails, while standard SKY is better suited to tetras and rare soft-water plants. Both can be used for suitable shrimp setups.

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Key Specifications

Brand: The 2Hr Aquarist
Product: APT SKY
Product Type: GH Booster / Aquarium Remineraliser
Form: Powder
Primary Function: Increase General Hardness (GH)
Designed For: RO/RODI and soft water
Effect on GH: Raises GH
Effect on KH: Does not intentionally increase KH
Effect on pH: Leaves pH unchanged
Effect on NPK: Designed not to alter calibrated NPK nutrient levels

Reference Dosage

3.5 g / 5 ml per 60 L provides approximately:

• Calcium: +12 ppm

• Magnesium: +3.5 ppm

• GH: +2.5 dGH

Recommended RO/RODI Baseline

10.5 g / 15 ml per 60 L

Manufacturer-Listed Composition

• Calcium (Ca): 21.5%

• Magnesium (Mg): 5.4%

• Iron (Fe): 0.06%

• Boron (B): 7 mg/L

• Copper (Cu): 1 mg/L

• Manganese (Mn): 17 mg/L

• Molybdenum (Mo): 0.01 mg/L

• Zinc (Zn): 9 mg/L

• Seaweed extract: <1%

Available YASAM Variants

• SKY 150 g

• SKY 800 g

• SKY+ 150 g

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Additional Product Notes

Raises GH Without Raising KH

This is the defining feature of APT SKY.

GH primarily reflects minerals such as calcium and magnesium, while KH reflects carbonate hardness and buffering capacity.

APT SKY allows aquarists to increase mineral hardness without simultaneously pushing KH upward.

This is useful in planted aquariums containing species that benefit from additional minerals but where low KH is desirable.

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Designed With Planted Tanks in Mind

Many commercial aquatic plants tolerate or prefer relatively low KH, while livestock such as shrimp still require adequate mineral availability.

APT SKY is designed to help provide these minerals without interfering with the aquarium's existing fertiliser NPK balance.

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Useful for Shrimp Tanks

Calcium and magnesium are important minerals in freshwater aquarium systems.

APT SKY can therefore be useful when remineralising very soft or RO/RODI water used for shrimp aquariums.

However, different shrimp species require different GH, KH, pH and TDS ranges, so the correct dose should be determined by the livestock being kept rather than assuming one universal shrimp-water target.

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SKY vs SKY+

Do not choose based only on price or container size.

Choose according to the water chemistry required:

Want GH ↑ while KH stays low? → APT SKY

Want GH ↑ plus some KH and pH buffering? → APT SKY+

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How To Use

For RO/RODI or Very Soft Water

The manufacturer's baseline recommendation is:

10.5 g / 15 ml per 60 L of RO/RODI water.

However, dosing according to your measured starting GH and desired target GH is more precise.

Step-by-Step

1. Test the GH of your source water.

2. Determine the GH appropriate for your aquarium's livestock and plants.

3. Calculate the amount of APT SKY required.

4. Measure the powder accurately.

5. Either:

   • add the powder directly to the aquarium or water-change water, or

   • mix it first with some water in a separate container and add the milky mixture.

6. Allow the aquarium water to circulate.

7. Retest GH where necessary.

8. During future water changes, remineralise based on the volume and GH of the new replacement water, rather than repeatedly dosing the entire aquarium volume.

Reference Increase

Every:

3.5 g / 5 ml per 60 L

raises GH by approximately:

2.5 dGH

and adds approximately:

• 12 ppm calcium

• 3.5 ppm magnesium

For accurate and repeatable remineralisation, measuring the product by weight is preferable to relying only on volume.

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Good To Know Before Buying

This is not medication

APT SKY does not treat:

• Fin rot

• Ich / white spot

• Velvet

• Bacterial infections

• Fungal infections

• Parasites

It is a water remineralisation product used to adjust mineral hardness.

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APT SKY does not raise KH

This is intentional.

If your livestock requires additional carbonate hardness and pH buffering, APT SKY+ may be the more appropriate product.

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Do not automatically use it just because you keep shrimp

Measure your water first.

If your water already has an appropriate GH for your shrimp species, adding more remineraliser may be unnecessary.

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Dose according to GH, not TDS alone

TDS measures the total amount of dissolved ions but does not tell you which minerals are present.

The manufacturer recommends using GH and an accurately measured dose rather than trying to reach a specific TDS number alone.

As a rough reference, the manufacturer notes that RO water remineralised to approximately 5–7 dGH often measures around 85–150 ppm TDS, but this varies and should not be treated as the main dosing target.

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Do not make large water-parameter changes suddenly

When changing GH or switching from tap water to remineralised RO water, consider the needs of your existing livestock and avoid abrupt changes in water chemistry.

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APT SKY is concentrated

The manufacturer describes APT SKY as approximately 3× as concentrated as conventional remineralisers, so measure carefully rather than adding powder freely.

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It cannot make hard water soft

APT SKY adds minerals—it does not remove them.

If your tap water is already hard or has high KH, adding APT SKY will not turn it into soft water.

For aquariums requiring genuinely soft water, starting with RO/RODI or naturally soft water may be necessary.

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Standard planted-tank reference ≠ universal livestock target

The manufacturer notes that many planted tanks perform well around GH 6, but this is not a universal requirement.

The correct GH depends on:

• Fish species

• Shrimp species

• Snails

• Plants

• Existing water chemistry

Always target parameters appropriate for the livestock you actually keep.