Vendor:The 2Hr Aquarist

2Hr Aquarist APT 1

Q: Which APT is right for me? APT 1 vs APT 3 vs APTe

If you're new to the hobby, have a sparse tank, have more fish or if you are especially wary of algae, start with APT1: it contains no added nitrate or phosphate, so there's less for algae to feed on while you get established. As the tank matures and plant mass grows, take a nitrate reading: Nitrate keeps climbing week to week → your fish are outpacing your plants. Stay on APT 1. Nitrate reads low or zero → your plants are consuming everything. Move up to APT 3 (or APTe for very heavily planted tanks).

Q: Is APT Safe for Shrimp?

APT 1 is safe for shrimp and all aquarium livestock. We keep thriving Caridina and Neocaridina shrimp in every one of our display tanks; some of our Neocaridina colonies are more than 5 years old. APT 1 does not harm shrimp even if it is significantly overdosed. If you are seeing shrimp losses, the cause is almost always a shift in water parameters - KH/TDS, temperature, or a large or rapid water change - or an acclimation issue, rather than fertiliser. If it keeps happening, send us your parameters and we'll help you work through it.

Q: Can I combine with APT 3 or APT e?

Yes, you can do 'half APT1, half APT3' for instance, or dose APT1 on Monday, APT 3 on Tuesday, then APT1 on Wednesday etc. Whatever your chosen pattern, consistency is key and simplicity helps :)

$23.90

2Hr Aquarist APT 1 provides a comprehensive blend of macro, micro and trace nutrients, with zero nitrates and phosphates for tanks with higher fishloads. The choice of award winning aquascapers. Unique Capstone Ratio unlocks richer reds and stronger growth.

INSTRUCTIONS

3ml / 100L per day
0.1 fl oz / 26 USgal per day

Dose any time of day, consistently.
Check Dosage Calculator for tanks without CO2 or mostly slow-growers / shade plants.
Minor sedimentation / crystallization is normal.

WHY

APT 1 (previously called APT Zero) replicates APT 3's winning formula without nitrates and phosphates. This gives maximum algae control for new tanks (we recommend all tanks to start with APT 1 for the first 1-3 months), and optimal long term performance for tanks with more fish. This is because fish food and waste already supply phosphates and nitrates.

INGREDIENTS

GUARANTEED ANALYSIS
Soluble Potash (K2O)....................................... 5.5%
Magnesium (Mg)............................................. 0.85%
Iron (Fe) ...........................................................0.1%
0.1% Chelated Iron

Derived from: Potassium Sulphate, Potassium Chloride, Magnesium Sulphate, DTPA Iron, EDTAIron, EDDHA Iron. Further information here.

Product variants

2Hr Aquarist APT 1

Standard

$23.90

6X Power

Example of APT's relative concentration compared with a 50-year old European 'big brand fertiliser'. APT contains 5X the amount of Phosphorus (P) and 6X Potassium (K) per ml. That is like having 5 shots instead of 1 in your morning espresso, if you are into coffee :)

Optimal Balance

Simply 'more' is not always better. Lower Nitrogen (N) delays chlorophyll production and promotes richer colors- up to a point. Nitrogen is also essential for metabolism. APT pushes the limits of that balance. Maximum color before diminishing returns.

Superior Form

Similar to food labels, "20% protein" or "1% Iron" tells little about actual absorbability, efficacy, and impact. APT's components are up to 50X more absorbable and accessible across a wider range of pH and other water parameters.

Dosage

Use the Dosage Calculator. Absolute precision isn't necessary: when in doubt, dose slightly less, not more. Consistency is much more important than being 100% accurate.

Timing

Changing fertilizers can trigger a temporary system shock. In rare cases, this results in widespread algae. This can be mitigated by introducing APT incrementally over 2 weeks.

Switching?

Changing fertilizers can trigger a temporary system shock. In rare cases, this results in widespread algae. This can be mitigated by introducing APT incrementally over 2 weeks.

Which APT?

APT 1 is perfect for tanks with more fish, fewer plants. Also for new tanks (<3 months) with aquasoil. Enjoy comprehensive nutrition without nitrates and phosphates for maximum algae control.

APT 3 is perfect for tanks with more plants, fewer fish. Enjoy 100% comprehensive macro, micro and trace minerals. Unlocks the full potential of the hobby's most demanding plants.

APT e is perfect for heavily planted Dutch Style tanks and users who understand EI methodology. Supremely concentrated and expertly balanced.

Deeper Reds Built-In

APT 3's nitrate-limiting ratio is specifically engineered to bring out deeper reds in species like Rotala rotundifolia and Ludwigia arcuata, while still providing everything plants need to thrive.

Modern Plant Science

APT's proprietary Capstone formulation was developed specifically for today's planted aquariums, factoring in current tank environments, new plant hybrids, and evolving light and CO2 technologies, unlike conventional fertilisers that trace their origins to 1970s fish-focused tanks.

FAQs

Please read our FAQs page to find out more.

Which APT is right for me? APT 1 vs APT 3 vs APTe

If you're new to the hobby, have a sparse tank, have more fish or if you are especially wary of algae, start with APT1: it contains no added nitrate or phosphate, so there's less for algae to feed on while you get established. As the tank matures and plant mass grows, take a nitrate reading:

Nitrate keeps climbing week to week → your fish are outpacing your plants. Stay on APT 1.
Nitrate reads low or zero → your plants are consuming everything. Move up to APT 3 (or APTe for very heavily planted tanks).

Is APT Safe for Shrimp?

APT 1 is safe for shrimp and all aquarium livestock.

We keep thriving Caridina and Neocaridina shrimp in every one of our display tanks; some of our Neocaridina colonies are more than 5 years old. APT 1 does not harm shrimp even if it is significantly overdosed.

If you are seeing shrimp losses, the cause is almost always a shift in water parameters - KH/TDS, temperature, or a large or rapid water change - or an acclimation issue, rather than fertiliser. If it keeps happening, send us your parameters and we'll help you work through it.

Can I combine with APT 3 or APT e?

Yes, you can do 'half APT1, half APT3' for instance, or dose APT1 on Monday, APT 3 on Tuesday, then APT1 on Wednesday etc. Whatever your chosen pattern, consistency is key and simplicity helps :)

The 2Hr Way

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June 19, 2026
0 commentson Good parameters, Good CO2, Good light, Poor plant growth?

Good parameters, Good CO2, Good light, Poor plant growth?

This article explains why aquatic plants sometimes do not grow well in a planted aquarium despite having good growth parameters available. It demonstrates how clearing old growth above and below the substrate allows new growth to be rejuvenated better than just trimming.