The Complete 2026 Guide to Hydroponic Nutrients & Additives in Australia

Quick-Start Deficiency Cheat-Sheet 🔍

Leaf Symptom

Likely Issue

Fast Fix

Lower leaves yellowing, pale veins

Nitrogen shortage

Increase base feed dosage.

Purpling stems, sluggish growth

Phosphorus gap

Add GP3 Bloom or a PK enhancer

Rusty spots, interveinal yellowing

Ca/Mg deficit

5 ml/L of Pro Cal

Burnt tips, clawing

EC too high

Dilute tank + re-check with a Bluelab Combo Meter

Droopy new leaves, glassy sheen

Silica shortage

1 ml/L of Plant Guard

1. Hydro Basics—Macros, Micros & Why Ratios Rule

Plants devour N-P-K in veg, then swing hard to P & K in bloom. A three-part such as GP3 Grow/Micro/Bloom lets you dial each element instead of being stuck with a single-bottle guess.

Pro tip: Keep your reservoir between EC 1.2–2.0 mS cm⁻¹ and pH 5.8–6.3 (coco or recirculating hydro). Daily measurement beats reviving a salt-locked crop.

2. Additives 101—When the Base Isn’t Enough

Additive Type

What It Does

Dr Greenthumbs Pick

Full Starter Kit

Unlocks bound nutrients & shields roots

Plant Mechanics Starter Kit

Cal-Mag

Buffers RO/tank water, prevents tip necrosis

Pro Cal or CMX

Silica

Thickens stems, boosts pest resistance

Plant Guard or GT Silica

Carb boosters

Feeds microbes, sweetens terps

Liquid Weight or Terpene Gold

Enzymes

Digests dead roots, keeps lines clean

Multizyme 

Add only one new booster at a time and watch runoff EC—additives still count toward total conductivity.

If you’d rather keep things simple with a reliable two-part system, A & B Nutrients: The Ultimate Australian Guide to 2-Part Hydroponic Feeding (2025) shows how to run clean, predictable reservoirs without juggling multiple bottles.

3. Aussie Water Tweaks—City by City

City

Typical Source EC*

pH Tendency

What to Watch

Sydney

0.3 – 0.6

Slightly acidic

Often needs 0.5 mL/L Pro Cal

Melbourne

0.1 – 0.4

Neutral

May need extra Ca late bloom

Perth

0.5 – 0.8

Alkaline

Pre-filter or pH-down aggressively

Brisbane

0.2 – 0.5

Neutral-alkaline

Check bicarbonates after heavy rain

*Ranges from recent BOM reports—always test your own source.

And once pH and water hardness are dialled in, Silica for Plants in Australia: The No-Nonsense Guide to Stronger, Happier Crops explains how silica further stabilises growth during heat spikes.

4. Troubleshooting Gallery

  • Yellow striping up leaf centre: calibrate your meter before blaming iron.

  • Copper mottling on older fans: 1 mL/L Pro Cal & raise pH to 6.2.

  • Leaf tips curling down but EC is fine: root zone too cold—run tank 18–22 °C.

5. Product Picker—Turn Knowledge into Yields

Grower Type

“Can’t-Go-Wrong” Pack

Beginner on coco

GP3 3-Pack + Bluelab pH Pen

LED hobby tent

Green Planet Starter Kit

Recirculating DWC

House & Garden Aqua Starter Kit

Coco × CO₂

GP3 full line + PK Spike + Liquid Weight + Bluelab Combo Meter

Every product links straight to our NSW warehouse shelves for fast Aussie delivery.

6. FAQ

How often should I change my reservoir?
Small hobby setups: weekly. Anything 100 L + with chillers: fortnightly or when EC drift hits ±0.3.

For crop-specific nutrient curves—especially for heavy fruiters—our Hydroponic Strawberry Nutrition: Ultimate 2025 Australian Guide lays out EC, pH and Part A/B adjustments for maximum sweetness.

Do I need RO water?
Only if source EC > 0.8 mS cm⁻¹ or loaded with bicarbonates. Otherwise, Pro Cal balances most tap water.

Ideal pH for NFT herbs?
5.8 – 6.0 keeps iron and calcium in the sweet spot.

Ready to grow smarter?

Have a curly question? Call 1800 983 006 or fire off an email—no bots, just real gardeners.

Happy growing, legends! 🌱

About the Author

Scott Cheney - Dr Greenthumbs
Scott Cheney is the Director and Founder of Dr Greenthumbs, with over a decade of hands-on experience in organic gardening. Growing up in rural NSW, Scott’s passion for unusual plants – from cacti to entheogens – evolved into a full-blown commitment to chemical-free gardening when he bought his first property in Wollongong. For the past 8 years running Dr Greenthumbs, Scott has developed unique, first-to-market products like TurboDirt Water Only soil and 100% dry amendment fertiliser blends. When he’s not testing new mixes, you’ll find him swapping gardening tips like your local mate, not giving the hard sell.