Terra Aquatica Feeding Guide: EC Targets, Ratios and How to Build Your Program

Every Terra Aquatica feeding chart comes with recommended doses. Those numbers are a ceiling, not a target. Running your plants at the maximum recommended EC from day one is one of the most common mistakes in hydroponic growing, and it costs growers yield, quality, and often entire crops.

This guide covers how to build a Terra Aquatica feeding program that actually works across different plant varieties, grow systems, and Australian growing conditions — starting with the principle that matters most: start lower than you think you need to, and build up deliberately based on what your plants are telling you.

The Bottle Is a Ceiling, Not a Target

Terra Aquatica, like every serious nutrient manufacturer, prints maximum dosage recommendations on their products. These numbers represent the upper limit a typical healthy plant in optimal conditions can handle without showing stress. They do not represent the dose every plant needs, or the dose your plant needs right now.

Plant nutrient requirements are not fixed. They vary based on growth stage, plant size, root development, light intensity, environment, and genetics. A small seedling in a cool room under modest lighting needs a fraction of the EC that a large, well-rooted plant in a dialled-in environment under high DLI can handle. Feeding both at the same EC based on the bottle recommendation will overfeed one and potentially underfeed the other.

The correct approach is to start at a conservative EC, observe your plants, and build up only when the plant demonstrates it can handle and use more.

Start Low and Build Up

A practical starting point for most seedlings and young vegetative plants is 50 to 60 percent of the maximum recommended dose. For Terra Aquatica NovaMax, that means starting around 1.0 to 1.5ml per litre rather than the maximum 2.5ml. For TriPart, start with ratios that produce an EC of 0.6 to 1.0 mS/cm rather than targeting 1.8 to 2.0 from the outset.

From that starting point, increase EC gradually over successive feedings as the plant grows, the root system develops, and environmental conditions stabilise. Small, regular increases give you visibility into how your plants are responding. A single large increase makes it impossible to identify what caused a problem if one develops.

It is always safer to err on the side of caution. A plant running slightly under its optimal EC will grow a little more slowly. A plant running above what it can handle will show nutrient stress that can take a week or more to recover from, and in some cases will never fully recover before harvest. The asymmetry of those outcomes makes conservative feeding the correct default.

What Actually Determines How Much EC Your Plants Need

Four variables interact to determine the EC your plants can productively use at any given point in the grow. Understanding each one helps you make better feeding decisions than any fixed chart can provide.

DLI: Daily Light Integral

DLI measures the total amount of photosynthetically active light your plants receive over a 24-hour period, expressed in mol/m²/day. It is the most important factor in determining how hard your plants are working and how much they can eat.

Plants under low DLI — a seedling tent, a propagation space, a grow room with older or lower-output lights — are photosynthesising less and therefore processing fewer nutrients. Feeding these plants at the EC appropriate for a high-DLI flowering environment will overfeed them. Plants under high DLI — a well-dialled LED grow at optimal PPFD, CO2-enriched environments, peak summer outdoor light — can handle and benefit from higher EC because they are converting more light into growth and using more nutrients to do so.

As you improve your lighting, move to higher-output fixtures, or increase your photoperiod, your plants' capacity to use nutrients increases. EC should follow that increase, not precede it.

Environment and VPD

Plants in a well-managed environment — stable temperature, correct VPD, good canopy airflow — transpire efficiently and move nutrients through their tissue at a higher rate than plants in a suboptimal environment. A plant in correct VPD range with strong canopy movement can absorb and use significantly more nutrient than the same plant in a hot, still, or overly humid environment where transpiration is suppressed.

If your environment is still being dialled in — if temperatures are irregular, if humidity swings between lights on and lights off, if VPD is outside the optimal range — reduce your EC target until conditions stabilise. Pushing EC in a stressed environment compounds the stress rather than improving growth.

Plant Health and Root Development

The root system is the plant's nutrient absorption interface. A small, underdeveloped root system limits how much nutrient the plant can take up regardless of EC. A large, healthy, well-oxygenated root mass can handle and actively use higher EC without accumulation stress.

Watch root development as your indicator of when to increase EC. When roots are visibly healthy and vigorous — white, dense, well-oxygenated — increase EC. When roots are stressed, brown, or limited, hold EC at current levels or reduce slightly until root health recovers.

Plant Size and Growth Stage

Larger plants with more leaf mass and greater canopy area have higher nutrient demand than smaller plants, even at the same growth stage. A large, well-trained canopy heading into mid-flower is drawing on significantly more resources than the same plant in week one of flower. EC should reflect the actual size and demand of your canopy, not a stage-based assumption.

Every Variety Is Different

One of the most consistent observations from experienced growers is that different plant varieties respond differently to EC, even under identical growing conditions. Some genetics are heavy feeders that push confidently through higher EC and show deficiencies at lower levels. Others are sensitive and show tip burn or lockout at EC levels that would be conservative for a different variety.

This means feeding charts, including this one, are starting points and frameworks. The only reliable guide to the optimal EC for your specific variety is direct observation of that variety across a grow cycle. Keep notes. If a variety consistently shows claw, tip burn, or lockout at a given EC, that is your data point. If a different variety looked underfed at the same level, that is equally useful information. Over time, your notes on variety-specific EC responses are more valuable than any published chart.

TriPart Ratios by Growth Stage

TriPart gives you three adjustable components: Micro, Grow, and Bloom. Always add Micro to water first, then Grow, then Bloom, mixing thoroughly between each addition.

Seedling and early propagation: EC 0.4 to 0.6 mS/cm. Start with a light Micro-forward mix. Some growers use Micro only at this stage. The priority is root development, not pushing vegetative growth.

Vegetative growth: EC 0.8 to 1.4 mS/cm, building gradually as the plant establishes. Use a balanced Grow-forward ratio — typically equal parts Micro and Grow with a smaller Bloom component. Build toward the upper end of this range only when root development is strong and environment is stable.

Transition and early flower: EC 1.2 to 1.6 mS/cm. Begin shifting the ratio toward Bloom while maintaining Micro. Reduce Grow as the plant's nitrogen demand decreases and phosphorus and potassium demand increases.

Mid to late flower: EC 1.4 to 1.8 mS/cm for most varieties in optimal conditions. A Micro and Bloom dominant ratio. Build to the upper end of this range only in well-established plants with high DLI and stable environment. If your environment has issues, stay in the lower half of the range.

Final flush: Reduce EC significantly in the final one to two weeks. Many growers flush with plain pH-adjusted water or a very light Micro-only solution to clear residual salts from plant tissue before harvest.

NovaMax Dosing by Growth Stage

NovaMax simplifies the ratio decision — Grow for veg, Bloom for flower. The EC management principles are identical.

Seedling and early veg: 0.5 to 1.0ml per litre of NovaMax Grow. Start at the lower end and build as the plant establishes.

Vegetative growth: 1.0 to 1.5ml per litre of NovaMax Grow, building gradually. Maximum 2.0ml per litre for large, well-rooted plants in high-DLI environments.

Flowering: Transition to NovaMax Bloom. Start at 1.0ml per litre at the beginning of flower and build to 1.5 to 2.0ml per litre through mid-flower as plant demand increases.

Final flush: Reduce to 0.5ml per litre or flush with plain water in the final week or two.

Hard Water and Soft Water in Australia

Water quality varies significantly across Australian regions and affects how you approach EC management. TriPart Micro is available in both hard water and soft water versions specifically to address this.

If your tap water has a baseline EC above 0.4 mS/cm, account for that in your total EC target. A target of 1.2 mS/cm does not mean you add nutrients to reach 1.2 mS/cm on top of your tap water EC — it means your final solution should read 1.2 mS/cm total, including the baseline.

Perth and much of regional Western Australia have notably hard tap water with high mineral content. Sydney and Melbourne tap water is generally softer. If you are unsure of your water quality, a baseline EC reading before adding nutrients will tell you what you are working with. If tap water EC is consistently above 0.5 mS/cm, consider using TriPart Micro Hard Water version and reducing your nutrient dose accordingly, or use RO or filtered water as your base.

Reading Your Plants

No feeding chart replaces direct observation of your plants. The signs your plants give you are the most accurate data you have.

Signs your EC may be too high: Tip burn on new growth, curling or clawing of leaves, brown leaf edges, slow growth despite good light and environment, visible salt deposits on growing media or reservoir walls.

Signs your EC may be too low: Yellowing of lower leaves, pale or light green colouration, slow growth rate relative to your DLI and environment, weak stems, reduced flower development.

Signs your EC is in range: Deep green healthy colour appropriate to growth stage, strong vigorous growth rate, good stem strength, active flowering development without tip burn.

When in doubt, reduce EC by 10 to 15 percent, observe for three to five days, and adjust from there. It is far easier to recover a slightly underfed plant than to reverse the damage from overfeeding.

Terra Aquatica Nutrients at Apex Grow

The full Terra Aquatica range is available at Apex Grow with fast tracked shipping Australia-wide. TriPart Micro, TriPart Grow, and TriPart Bloom are available individually or as a complete system. NovaMax Grow and NovaMax Bloom are stocked for growers who prefer the 1-part approach. Browse the full Base Nutrients collection for the complete range.

Frequently Asked Questions

What EC should I start with for seedlings using Terra Aquatica?
Start at 0.4 to 0.6 mS/cm for seedlings and young clones. This is significantly lower than most feeding charts suggest but matches what a young root system can actually process. Build up gradually as roots develop and plants establish.

Can I use the same EC for all plant varieties?
No. Different varieties have genuinely different nutrient requirements. Some are light feeders that show stress at moderate EC. Others are heavy feeders that benefit from higher EC through mid-flower. Use the ranges in this guide as starting points and adjust based on how your specific variety responds over time.

Should I follow the Terra Aquatica feeding chart exactly?
Use it as a reference for ratios and a ceiling for EC, not as a precise recipe. The chart assumes optimal conditions, established root systems, and average genetics. Your actual situation likely differs from all three of those assumptions. Start at 50 to 60 percent of the maximum recommended dose and build up based on plant response.

How often should I change my nutrient solution?
In recirculating systems, a full reservoir change every 7 to 10 days is a common practice. Between changes, top up with fresh nutrient solution at a slightly lower EC than your target to account for the concentration that occurs as plants drink water and leave some nutrients behind. Test EC before topping up and adjust accordingly.

What is the difference between TriPart Hard Water and Soft Water Micro?
Hard Water Micro is formulated for water sources with high calcium and magnesium content, reducing the risk of nutrient lockout from excess minerals. Soft Water Micro adds calcium and magnesium to compensate for water that lacks these elements. Use Hard Water Micro if your tap water EC is consistently above 0.4 to 0.5 mS/cm, and Soft Water Micro if your water is very pure or if you are using RO water as your base.

My plants look pale but my EC is already at the recommended level — what should I do?
Check pH first. Nutrient lockout from pH drift is far more common than actual nutrient deficiency and produces identical symptoms. If pH is correct and locked out nutrients are ruled out, check your environment — low VPD, poor airflow, or root zone issues can all suppress uptake regardless of what is in the reservoir. Only increase EC after ruling out environmental and pH causes.