Dashboard
Dashboard
Quick reference
The three numbers every hydroponic grower needs
pH target
5.5 – 6.5
For most crops. Outside this range nutrients are in the water but roots cannot absorb them.
EC target (mS/cm)
Reservoir changes
7 – 14 days
Full replacement. Top up with plain pH-adjusted water between changes — plants drink water faster than nutrients.
Nutrients
By HiGroPonics Team · Updated June 2026
Of all the variables in hydroponics, two numbers are responsible for more plant problems than everything else combined: pH and EC. Get these right and most other problems take care of themselves.
This guide explains what each number means, why it matters, how to measure it accurately, and how to correct it when it drifts.
Part 1
Keep pH between 5.5 and 6.5 — outside this window nutrients are dissolved in the water but your plant cannot absorb them.
pH measures how acidic or alkaline your nutrient solution is, on a scale of 0–14, with 7 being neutral. In hydroponics, most crops grow best between pH 5.5 and 6.5.
Each nutrient has a specific pH range in which it becomes available for roots to absorb. Outside that range the nutrient is still present in the solution — but it forms compounds that roots cannot access. This is called nutrient lockout, and it is the most common cause of deficiency symptoms in hydroponic plants.
Key rule
If your plant looks deficient but your EC is correct, check pH first — every time. pH out of range causes deficiency symptoms even when nutrients are present.
Scale shown from pH 4.0 to 8.0 — coloured bar shows the optimal absorption window.
Part 2
EC tells you how strong your feed is — too low and plants starve, too high and roots burn. The right target changes with crop and growth stage.
EC (Electrical Conductivity) measures how many dissolved nutrient salts are in your water, expressed in mS/cm. Pure water conducts no electricity — the more dissolved minerals, the higher the reading.
EC tells you how much nutrient is in the solution, not what nutrients. Too low and plants are underfed; too high and the osmotic pressure pulls water out of roots rather than in — causing nutrient burn and wilting even with plenty of water present.
Note on TDS/PPM
TDS meters show PPM, converted from EC using a factor (usually 0.5 or 0.7). EC is more universal — always record EC rather than PPM to avoid confusion between meter conversion factors.
| Crop | Seedling / Clone | Vegetative | Flowering / Fruiting | Late Stage / Flush |
|---|---|---|---|---|
| Lettuce / Leafy Greens | 0.8–1.2 | 1.2–1.6 | — | 0.0 (plain water) |
| Herbs (Basil, Mint) | 0.8–1.2 | 1.2–1.8 | — | 0.0 |
| Tomatoes | 1.0–1.5 | 2.0–2.5 | 2.5–3.5 | 0.0–0.5 |
| Peppers | 1.0–1.5 | 1.8–2.2 | 2.0–3.0 | 0.0–0.5 |
| Cucumbers | 1.0–1.5 | 1.5–2.0 | 2.0–2.5 | 0.0–0.5 |
| Strawberries | 0.8–1.2 | 1.4–1.8 | 1.6–2.2 | 0.0–0.5 |
Plants are being underfed. Leaves may be pale, growth slow, older leaves yellowing from nitrogen deficiency.
Fix: Add more nutrient concentrate to the reservoir in small increments. Do not jump EC by more than 0.2–0.3 mS/cm per day to avoid shocking plants.
Nutrient burn. Leaf tips and edges brown and curl. Wilting despite adequate water. Roots may look stressed.
Fix: Dilute the reservoir by removing some solution and replacing with pH-adjusted plain water. Avoid large sudden EC drops.
Part 3
Plants require 17 essential elements to complete their life cycle. In soil, many are supplied naturally — in hydroponics, every one must come from your nutrient solution.
Needed in the largest quantities. The three numbers on every nutrient label.
Role
Drives leafy, vegetative growth. A key component of chlorophyll and amino acids. High-N formulas are used during the vegetative stage.
Deficiency / Excess signs
Deficiency: yellowing of older leaves, starting at the tips. Slow, stunted growth. Excess: very dark green leaves, soft lush growth susceptible to pests.
Role
Essential for root development, flower initiation, and energy transfer (ATP). High-P formulas (PK boosters) are used during flowering and fruiting.
Deficiency / Excess signs
Deficiency: purple or red tinting on leaf undersides, slow growth. Excess: can lock out zinc and iron at high concentrations.
Role
Regulates water movement in plant cells, strengthens cell walls, and improves disease resistance. Works alongside P during flowering to improve fruit quality and yield.
Deficiency / Excess signs
Deficiency: brown scorching on leaf edges (marginal necrosis), starting on older leaves. Weak stems. Excess: can inhibit calcium and magnesium uptake.
Needed in significant quantities — often missing from low-quality nutrient formulas.
Role
Cell wall structure, root development, and nutrient transport. Immobile — must be continuously supplied as new growth cannot borrow calcium from older tissue.
Deficiency / Excess signs
Deficiency: tip burn, blossom end rot on tomatoes/peppers, distorted new growth. Poor airflow worsens deficiency even with correct pH and EC.
Role
The central atom in every chlorophyll molecule — no magnesium means no green colour and no photosynthesis. Mobile in plants, so deficiency shows in older leaves first.
Deficiency / Excess signs
Deficiency: interveinal chlorosis on lower/older leaves — veins stay green while the leaf yellows between them. Often confused with iron deficiency (which affects new growth).
Role
Component of amino acids and proteins. Involved in flavour and aroma compounds. Rarely deficient in hydroponic systems as it is present in most sulphate-based nutrients.
Deficiency / Excess signs
Deficiency: uniform yellowing of young leaves. Rare in hydroponics with a complete nutrient formula.
Needed in tiny quantities — but deficiency causes serious symptoms. A complete base nutrient formula should supply all of these.
| Element | Symbol | Key Role | Deficiency Sign |
|---|---|---|---|
| Iron | Fe | Chlorophyll synthesis, enzyme function | Interveinal chlorosis on new leaves — most common micronutrient deficiency |
| Manganese | Mn | Photosynthesis, nitrogen metabolism | Interveinal chlorosis on middle-aged leaves, similar to iron |
| Zinc | Zn | Enzyme activation, growth hormone production | Small, distorted new leaves; short internodes |
| Copper | Cu | Protein synthesis, disease resistance | Bluish-green wilting leaves; tips curl and die. Rare in hydroponics |
| Boron | B | Cell wall formation, pollen viability | Distorted, brittle growing tips; hollow stems in some crops |
| Molybdenum | Mo | Nitrogen processing within the plant | Cupping or rolling of leaves. Very rare |
| Chlorine | Cl | Water regulation, photosynthesis | Deficiency extremely rare — tap water provides ample chlorine |
Seedling / Propagation
Low overall EC, balanced NPK
Young plants need gentle, balanced nutrition. High EC at this stage causes root burn. Use a half-strength or seedling-specific formula.
Vegetative Growth
High N, moderate P & K
Nitrogen drives leaf and stem development. A "grow" or "veg" formula (e.g. 3-1-2 ratio) supports rapid canopy expansion.
Flowering & Fruiting
Lower N, high P & K
Plants shift energy from leaves to flowers and fruit. Switch to a "bloom" formula and consider a PK booster at peak flowering. Excess nitrogen at this stage delays flowering.
Part 4
Liquid A+B is the industry standard; dry powder costs less per litre but needs precise scales; avoid organic nutrients in recirculating DWC or NFT systems.
The industry standard for home and commercial hydroponic growing. Nutrients are split into two bottles — Part A contains calcium and nitrogen, Part B contains phosphorus, potassium, and sulphates. They must be kept separate in concentrate form. Always add A to the water first, stir, then add B.
Pros
Cons
Popular brands
Canna Aqua, Canna Coco A+B, Athena Grow/Bloom, General Hydroponics Flora Series
All nutrients in a single bottle, stabilised with chelating agents to prevent precipitation. Convenient for small grows and beginners who want simplicity over fine control. Suited to leafy greens and herbs rather than fruiting crops.
Pros
Cons
Popular brands
Formulex, Ionic Grow/Bloom, MaxiGro (liquid), Vitalink Buddy
Highly concentrated salts that dissolve in water before use. Significantly cheaper per gram of nutrient than liquid equivalents. Require accurate scales (0.1g precision at minimum) and mixing order discipline. Long shelf life when kept dry.
Pros
Cons
Popular brands
GH MaxiGro / MaxiBloom, Plant Magic Mush Coco, Masterblend 4-18-38
Derived from plant, animal, or mineral sources. Organic nutrients are broken down by microbial activity, making them slower acting. Better suited to media-based grows than recirculating DWC/NFT systems where undissolved organics can foul reservoirs.
Pros
Cons
Popular brands
BioBizz Grow/Bloom, BioTabs, Plagron Organic, Canna Bio Vega/Flores
This is the most critical concept for anyone using a multi-part nutrient system — and the most common mistake beginners make.
The chemistry
Certain elements — specifically Calcium — react violently with Sulphates and Phosphates when they meet in a concentrated form. The reaction causes them to bind together and fall out of solution as a white, chalky solid. This is called precipitation.
Once precipitated, those nutrients are locked into an insoluble solid your plants cannot absorb — even though they are physically present in the water. This is nutrient lockout caused by chemistry, not pH.
What goes in each part
Part A — the calcium side
Contains Calcium Nitrate and Iron. These are kept away from sulphates and phosphates in concentrate form.
Part B — the phosphate/sulphate side
Contains Phosphates, Sulphates, Potassium, and remaining micronutrients.
The safe mixing method — always
Note: Never pour A directly into B in the bottle, or mix them in a concentrated stock solution. Always dilute into water separately.
Base nutrients provide the full spectrum of what plants need. Supplements are optional additions. Do not reach for additives to fix a problem — first check pH, then EC, then root health.
CalMag
Calcium and magnesium supplement. Essential with soft water, RO water, or coco coir grows. Always use alongside A+B.
PK Boosters
High phosphorus and potassium formulas (e.g. Canna PK 13/14) added during peak flowering to support fruit development.
Silica
Strengthens cell walls, improves heat and pest resistance. Add before other nutrients — silica raises pH significantly.
Beneficial Bacteria
Products like Hydroguard colonise roots and suppress Pythium (root rot). Particularly useful in DWC and warm climates.
Enzymes
Break down dead root matter in the reservoir, reducing the load on beneficial bacteria and preventing blockages.
Amino Acids
Ready-made building blocks for plant proteins. May improve stress recovery and nutrient uptake efficiency.
Part 5 — Raw Salts
Three starting-point formulas using five raw salts — measure by weight, dissolve calcium nitrate first, then check pH after mixing.
For growers using dry raw salts. All quantities are per 4 litres of water. Always add salts one at a time, stirring fully between each, then check and adjust pH before use.
.webp&w=3840&q=75)
.webp&w=3840&q=75)
Per 4 litres of water
Target EC: 1.2–1.8 mS/cm
Ingredients
Compatible Plants
Per 4 litres of water
Target EC: 1.5–1.8 mS/cm
Ingredients
Compatible Plants
Per 4 litres of water
Target EC: 2.0–3.5 mS/cm
Ingredients
Compatible Plants
Note: These are starting-point recipes for fresh water at average mineral content. Your tap water's base EC and mineral profile will affect results — always measure EC and pH after mixing.
Calcium Nitrate must always be dissolved first, before any other salts. It contains Calcium, which reacts with the Sulphates and Phosphates in other components when concentrated — forming an insoluble white precipitate that locks out those nutrients. Adding each salt separately to water (not to each other) prevents this reaction. See the Why You Can Never Mix A and B Together section above for the full explanation.
Disclaimer: These are general-purpose mixes intended as a starting point only. Always research the specific nutritional needs of your chosen plants. Start with a weaker solution and increase strength gradually as plants establish.
Part 6 — pH & Nutrients
Most deficiency symptoms in hydroponics are pH lockout in disguise — check pH before buying supplements.
The most common nutrient lockout scenarios — knowing which pH range locks out which nutrient helps you diagnose deficiency symptoms faster.
Symptoms: Yellowing between veins on young leaves, veins stay green. Affects new growth first — iron is needed for chlorophyll production.
Fix: Reduce pH to 5.5–6.2. Iron becomes available again rapidly once pH is corrected.
Symptoms: Similar to iron deficiency but typically affects middle-aged leaves. Pale yellow patches between veins while veins remain green.
Fix: Reduce pH to the 5.8–6.3 range. Add a trace element supplement if symptoms persist.
Symptoms: Purple or red tinting on leaf undersides and stems. Slow growth, unusually dark green leaves in early stages.
Fix: Keep pH in the 5.8–6.5 range. Phosphorus is available across a wide window when pH is correct.
Symptoms: Brown scorching at leaf tips on young growth, blossom end rot on tomatoes and peppers, distorted new leaves.
Fix: Raise pH above 5.5. Add a CalMag supplement. Ensure good airflow — calcium uptake is driven by transpiration.
Symptoms: Interveinal chlorosis on older, lower leaves — yellowing between the veins while veins stay green.
Fix: Raise pH above 5.5. Add CalMag or Epsom salts. Check for calcium excess — high Ca can antagonise Mg uptake.
Symptoms: Distorted, thick, or brittle new growth. Growing tips may die or fail to develop. Hollow stems on some crops.
Fix: Reduce pH below 6.5. Do not over-supplement — boron toxicity appears at only slightly higher concentrations than deficiency.
Part 7
Most hydroponic problems come down to the same handful of avoidable errors.
More nutrients does not mean faster growth. Pushing EC above the recommended range stresses roots, causes tip burn, and makes plants more vulnerable to disease. Start at the lower end of the target range and only increase once plants are established and thriving.
pH drifts constantly — nutrient uptake, CO₂ from roots, and evaporation all shift it. Checking once a week is not enough. Once a day is the minimum for an active grow. A cheap digital pen pays for itself in avoided plant stress.
Lettuce and tomatoes have very different needs. Leafy greens thrive at EC 1.2–1.6; fruiting plants may need 2.5–3.5 at peak. Check the crop-specific targets in Part 2 and adjust accordingly.
A rising EC trend means plants are drinking water without consuming much nutrient — a sign of stress, heat, or the wrong formulation. A falling EC trend means they are consuming nutrients fast and the reservoir needs refreshing. The direction matters as much as the number.
Tap water already contains dissolved minerals — typically EC 0.1–0.5 depending on your region. If you mix nutrients without subtracting your baseline EC, you may be overfeeding without knowing it. Always measure your plain tap water first and factor it into your target. See Part 9 for more detail.
Part 8
See something wrong? Start here — most symptoms have one or two likely causes in hydroponics.
| Symptom | Where you see it | Most likely cause | First thing to check |
|---|---|---|---|
| Yellowing leaves | Older / lower leaves first | Nitrogen deficiency or pH too high (>6.8) | Check pH. If correct, increase EC slightly or switch to a higher-N formula. |
| Yellowing between veins | New / young leaves | Iron or manganese deficiency — pH too high locking them out | Drop pH to 5.8–6.2. Iron is the first thing to lock out above pH 6.5. |
| Brown tips or edges | Tips and margins of leaves | EC too high (nutrient burn) or potassium deficiency | Measure EC — if above target, dilute with pH-adjusted water. Check pH too. |
| Wilting despite full reservoir | Whole plant droops | EC too high (osmotic stress) or root rot (Pythium) | Check EC first. Then inspect roots — healthy roots are white; brown slime means Pythium. |
| Slow or stalled growth | All new growth affected | EC too low (underfeeding), pH out of range, or low temperature | Check pH and EC in that order. Water temperature should be 18–22°C. |
| No flowers / delayed flowering | Flowering-age plants only | Nitrogen too high in bloom stage, or photoperiod issue | Switch to a lower-N bloom formula. Check that lights are on the correct schedule. |
| Purple/red stems or leaf undersides | Stems and leaf undersides | Phosphorus lockout or cold stress | Check pH (P locks out below 5.0 and above 7.0). Check water temperature. |
Always check pH and EC before concluding there is a genuine deficiency — the vast majority of visual symptoms in hydroponics are corrected by bringing these two numbers back into range.
Part 9
Your water is the base of every nutrient solution — its mineral content affects your EC baseline and your nutrient formula choice.
Most tap water has an EC of 0.1–0.5 mS/cm depending on your local supply. That baseline counts toward your total EC target — always measure plain tap water before mixing nutrients and subtract it from your target.
Tap water also contains chlorine or chloramine. Chlorine dissipates if you leave water sitting in an open container for 24 hours; chloramine does not. In practice, the low concentrations found in tap water rarely harm plants in a properly aerated hydroponic system — but if you notice slow root development or reduced beneficial bacteria activity, it may be worth addressing.
Typical baseline EC
0.1 – 0.5 mS/cm
RO water has an EC near zero — almost pure H₂O with virtually no dissolved minerals. This gives you full control over your nutrient profile, but it also means you must supply everything the plant needs, including calcium and magnesium that tap water provides for free.
Always use a CalMag supplement when growing with RO water. Without it, calcium and magnesium deficiencies will appear even with a full A+B formula, because most base nutrients assume some baseline hardness from the water supply.
Baseline EC
0.0 – 0.05 mS/cm
Collected rainwater is generally soft and clean with a low EC — often similar to RO water. It is a good free alternative, but always check EC and pH before use as it can pick up contaminants from roof catchment or storage tanks.
Bore or well water varies enormously by region. It can have very high EC (hard water areas) or contain iron, sulphur, or other minerals that interfere with nutrient balance. Always test bore water with a full mineral analysis before using it in a hydroponic system.
Rainwater baseline EC
0.0 – 0.1 mS/cm
Takes 5 minutes. Do it at the same time each day — morning is best before lights-on temperature changes.
Full reservoir change schedule
Replace your entire nutrient solution every 7–14 days — not just top it up. Over time, nutrients are consumed unevenly and certain mineral salts accumulate. Topping up corrects volume and EC, but it does not reset the mineral balance.
Change sooner (every 7 days or less) if: EC or pH swings are hard to stabilise, you notice algae, roots look brown or smell off, or you have had a pest or disease issue. Change less frequently (up to 14 days) for established, stable grows with clean roots. Always flush with plain pH-adjusted water for 24 hours before a full change to clear salt buildup from growing media.
FAQ
Related Guides
Ready to set up your grow? Open the System Builder → for a checklist of what you need, indicative prices, and links to find everything.