Apex Grow Hydroponics

PlantMDx™

What's wrong with my plants?

Describe what you're seeing for a straight answer. For a proper diagnosis, fill in your numbers below. The tool ranks likely causes, rules out what doesn't fit, and tells you what to go and check when it can't decide.

Quick answer

Or run a full diagnosis
1 · The grow

The system list narrows to methods commonly used for the plant you choose, leafy greens and vine crops don't run the same way.

2 · Where the damage is

These two questions do more diagnostic work than any measurement. Leaf age separates the mobile nutrients that move out of old leaves from the immobile ones that show on new growth. Position separates light burn, heat and wind burn from anything systemic.

3 · Root zone oxygen

In water culture there is no dry-back and no such thing as overwatering. Roots sit in solution permanently and get their oxygen entirely from aeration and dissolved oxygen, which is governed by water temperature.

In media there are two strategies that both work: dry back properly between feeds so air is drawn in, or feed often enough with real runoff that fresh oxygenated solution keeps displacing the stale. What fails is the middle, frequent feeding with no runoff gives you neither.

Choose a system above and this section will ask the right questions for it.

4 · Water source

Hard water pushes pH up and adds EC before you've dosed anything. RO and rainwater have almost no buffering, so pH moves the moment anything changes.

5 · Readings

A small daily EC drift is normal, evaporation concentrates the solution faster than plants take it up. Top up with plain water and judge the trend over several days, not one reading.

6 · Climate
7 · Light

No PPFD meter? Check your fixture's spec sheet at your hanging height, or leave it blank. Fixture type still matters. HPS radiant heat lifts leaf temperature above air temperature and changes your VPD.

8 · What you're seeing

How PlantMDx reaches a diagnosis

PlantMDx is a rules engine, not a guessing machine. The same inputs always produce the same ranking, and every score is traceable to a stated reason.

Evidence is weighed, not counted

Each measurement and symptom you enter adds weighted evidence toward specific causes, and just as importantly subtracts evidence from causes it argues against. A reservoir at 19 degrees does not simply fail to indicate root rot, it actively counts against it. Greyed reasons in a result are evidence pointing away from that cause.

Work in layers, from the outside in

Every cause carries a layer tag: environment, hydration and root zone, chemistry, then nutrition. That order matters. Most growers start at nutrition because deficiency charts are the easiest thing to find, but a yellowing leaf far more often traces back to root zone oxygen, pH blocking uptake, or a climate that has stalled transpiration. When two causes score closely, PlantMDx breaks the tie toward the outer layer.

Position beats measurement

Two questions do more diagnostic work than any meter reading. Which leaves are affected first separates mobile nutrients, which the plant strips out of old growth, from immobile ones that show on new growth. Where the damage sits separates light burn, heat stress and wind burn from anything systemic. A pH pen cannot tell you either of these.

Root zone oxygen, not overwatering

There is no such thing as overwatering in hydroponics. Deep water culture roots sit in solution permanently and thrive. What matters is oxygen at the root surface, and water only matters because it displaces air. In water culture that oxygen comes from aeration and from what warm water can no longer hold. In media there are two strategies that both work, drying back properly between feeds or feeding often enough with real runoff, and the failure case is the middle ground where you get neither. PlantMDx asks different questions depending on which kind of system you run.

Confidence is separate from match strength

Match strength shows how strongly your inputs point at one cause relative to the others. Confidence shows how much the reading as a whole can be trusted, and it falls when data is thin or when two causes sit too close to separate. When that happens the tool tells you what to go and physically check rather than picking a winner.

Built for Australian conditions

Target ranges assume Australian indoor growing. Source water varies enormously across the country, from very soft supplies in Melbourne and Hobart to hard alkaline water in Adelaide and Perth, and that changes both your starting pH and how much calcium and magnesium you need to add. Summer reservoir control is the single biggest seasonal problem for Australian growers, and the thresholds here reflect that.

Every condition PlantMDx covers

The full reference behind the tool. Search above to filter this list, or browse by category. Each entry links to the detailed guide and the product that addresses it.

Root zone

Stagnant root zone

  • There is no such thing as overwatering in hydroponics. DWC roots sit in water permanently and thrive. What matters is oxygen at the root surface, and water only matters because it displaces air.
  • In media there are two strategies that both work: dry back properly between feeds so air is drawn in as water leaves, or feed frequently with real runoff so fresh oxygenated solution keeps displacing the stale.
  • What fails is the middle ground, frequent feeding with no runoff. You get neither dry-back nor refresh, just warm deoxygenated solution sitting in the medium with salts building alongside it.
  • Pick one strategy and commit. Either extend the gap between feeds until the pot actually gets light, or increase feed volume until you see 20–30% runoff every time.
  • Drooping the day after a feed with leaves still firm and thick is the tell. Limp papery leaves with dry medium is the opposite problem.

Troubleshooting index Grow media

Stale solution in the medium

  • Feeding often without runoff means the same solution sits in the medium getting warmer, more depleted and lower in oxygen with every cycle.
  • Salts concentrate at the same time, so EC in the root zone climbs well above what your reservoir reads.
  • The fix is volume, not frequency. Feed enough that 20–30% comes out the bottom.
  • Measure runoff EC against input. If runoff reads much higher, flush until the two converge before changing anything else.

Lockout & flushing Grow media

Container oversized for the root mass

  • A small root system in a large pot cannot drink enough to create dry-back, so the medium stays saturated no matter how carefully you water.
  • This is not a watering mistake. The plant is sitting in more medium than it has grown into.
  • Most common right after potting up too aggressively, or starting seedlings straight into final containers.
  • Pot down, or step up gradually so root mass and medium volume stay in proportion.

Troubleshooting index Pots & systems

Dissolved oxygen crash

  • In water culture, oxygen reaches the roots only through aeration and what the water can hold in solution.
  • Warm water holds less oxygen. Every 2 °C above 20 costs roughly 10–15% of your dissolved oxygen.
  • A weak air pump, a clogged stone or a kinked line drops it fast, and roots start dying within days.
  • You want a vigorous rolling boil across the whole reservoir, not a lazy trickle in one corner.
  • This is the stage before root rot. Fix it here and you avoid the pathogen entirely.

Air stone guide Air stones

Kratky water level wrong

  • Kratky works because the water level falls as the plant drinks, leaving an air gap where oxygen-seeking roots develop.
  • Keeping the reservoir topped right up removes that gap and drowns the very roots the method depends on.
  • Fill so the level just touches the base of the net pot at the start, then let it fall and don't top it back up mid-cycle.
  • If the level drops past all the roots the plant runs out of water, top up only when the water roots are nearly clear.

Troubleshooting index Pots & systems

Underwatering / dry-back too aggressive

  • Limp, papery, thin-feeling leaves with dry medium, the opposite feel to the firm, thick droop of a wet root zone.
  • Common in small pots, coco under high light, or when demand suddenly outgrows the schedule.
  • Feed more often with smaller volumes rather than one large flood, which channels straight through.
  • If it dries in under 12 hours consistently, the container is too small for the plant, not the schedule too slow.

Troubleshooting index Grow media

Root rot

  • Almost always Pythium, a water mould rather than a true fungus, so antifungal products don't treat it effectively.
  • Healthy roots are white or cream and firm; infected roots turn brown or grey, slimy, with a fishy or sewage smell.
  • Reservoir temperature is the biggest risk factor, above 22 °C dissolved oxygen drops, above 26 °C Pythium can take hold within 24 to 48 hours.
  • Drop reservoir temperature, boost aeration, trim affected root tissue and treat with a root-zone steriliser.
  • In a recirculating system one sick plant infects everything downstream, so treat the whole system, not the plant.

Root rot guide Guardian Hydro Clean

pH & EC

Inconsistent batch mixing

  • In drain-to-waste there is no reservoir chemistry to drift, you mix fresh every time, so variation between readings means variation in your mixing, not in the solution.
  • Common causes: not stirring fully between additives, dosing by eye, or adding pH adjuster before the nutrients are fully dissolved.
  • Mix the full batch, stir, wait 15 minutes, then take your reading and adjust. pH moves after nutrients dissolve.
  • Keep a written recipe and follow the same order every time. Consistency is the entire game in DTW.

Meter calibration Probe care kit

pH keeps dropping

  • Most often driven by nutrient uptake patterns, and later in a grow by decaying root matter in the reservoir.
  • Check root health first, a dropping pH can be an early warning of root problems before anything else shows.
  • Correct with pH Up, but treat the underlying cause rather than chasing the number daily.

pH dropping guide pH Up & Down

pH keeps rising

  • Most often caused by alkaline source water, particularly in harder water areas like Adelaide or Perth.
  • Algae in the reservoir consumes CO2 during the day, which pushes pH up as a side effect.
  • A small reservoir with less buffering capacity swings pH faster in both directions.
  • Repeatedly dosing pH Down without addressing the cause means it creeps back within a day.

pH rising guide pH Up & Down

Australian tap water

  • Yes, you can use tap water for hydroponics in Australia, but suitability varies significantly by city and region.
  • Hard water regions typically push pH upward and add background EC before you've dosed any nutrients.
  • Test your specific source water's pH and EC before assuming a feeding schedule applies as written.

Australian tap water pH & EC meters

Chlorine and chloramine

  • Chlorinated tap water kills beneficial bacteria and fungi on contact, so a bioactive program can fail on day one.
  • Chlorine gasses off if water stands for 24 hours. Chloramine does not, it needs filtering or a treatment product.
  • Most Australian mains supplies use chloramine rather than free chlorine, so ageing water alone often isn't enough.
  • If you're running sterile this doesn't matter. If you're paying for beneficials, it matters completely.

Sterile vs bioactive Water testing

pH meter inconsistent

  • Most inconsistent readings come from the probe, not the water. Recalibrate with fresh buffer solution.
  • If readings still drift after fresh calibration, the probe may be reaching end of life.
  • Store the probe wet between uses, letting it dry damages the sensing membrane permanently.

Meter calibration guide Probe care kit

What EC should I run

  • Target EC depends on crop type and growth stage, lower at seedling, higher through veg and flower.
  • Heavy flowering crops peak in early flower and often want a taper back down through the final weeks as uptake slows.
  • Evaporation concentrates the solution faster than plants take it up, so EC creeping upward over several days is expected, not a fault.
  • Top up a rising reservoir with plain water rather than more nutrient solution.

EC targets guide EC meter

EC rising or falling

  • Rising EC almost always means water is evaporating or being taken up faster than nutrients.
  • Falling EC usually means plants are taking up nutrients faster than water, common through heavy vegetative growth.
  • A small daily drift is completely normal. React to the trend over several days, not one reading.
  • A sudden large swing points to a meter fault, a dosing mistake or a leak, not normal plant behaviour.

EC drift guide EC meter

Cloudy reservoir / nutrient lockup

  • A cloudy tank with sediment means nutrients have precipitated out of solution and are no longer available.
  • Calcium locks with phosphate and sulphate when concentrates meet before they're diluted.
  • Mixing order matters: most of your water first, then silica, then cal-mag, then base A, stir fully, then base B.
  • Never pour concentrates together or into a part-filled tank. Once precipitated you can't stir it back in.

Troubleshooting index Base nutrients

Nutrients

Nutrient lockout

  • Deficiency despite a correctly mixed feed is a pH problem blocking uptake far more often than an actual shortage.
  • Salt buildup in the media can also block uptake even when the reservoir reads correct.
  • A full flush with plain, pH-adjusted water clears buildup and gives a clean baseline to re-diagnose from.

Nutrient lockout guide Base nutrients

Cal-Mag deficiency

  • Interveinal chlorosis, yellowing between veins while veins stay green, most common on RO or naturally soft water.
  • Calcium deficiency always makes brown spots. Spider mite damage starts pale or white and comes with visible bugs or webbing. That's how you tell them apart.
  • High-intensity LED lighting increases calcium and magnesium demand, so it shows even on adequate feed. Heavy flowering crops under strong light are the most common case.
  • Often worse on leaves at the top of the plant close to the light, which can be mistaken for light burn.
  • Low pH at the roots is the most common single cause. Check pH before adding anything.

Cal-Mag guide Cal-Mag

Potassium deficiency

  • Necrosis around the leaf margins of older leaves, a band following the edge, working inward.
  • The worst lookalike for nutrient burn, and the fix is the opposite direction.
  • Burn starts at the tip and works back; potassium bands the whole edge.
  • Potassium is mobile, so it always shows on older leaves first while new growth stays clean.
  • Very common in heavy flowering crops through peak bloom, when potassium demand climbs faster than most feed charts allow for.

Troubleshooting index Bloom additives

Phosphorus deficiency

  • Older leaves go dark, dull and slightly blue-green, often with bronze or purple patches and purpling petioles.
  • Cold root zones cause this far more often than an actual shortage, phosphorus uptake falls away below about 18 °C.
  • Check reservoir temperature before adding a bloom booster. Warming the root zone fixes most cases.
  • Also blocked at high pH, so confirm pH is in range before assuming the feed is short.

Troubleshooting index Bloom additives

Nitrogen deficiency

  • Uniform pale yellowing of the whole leaf, starting at the oldest lowest leaves and advancing upward.
  • Uniform is the key word, if the veins stay green it's cal-mag or iron, not nitrogen.
  • Nitrogen is mobile, so the plant strips it from old growth to feed new growth.
  • Some fade in late flower is normal and expected as the plant remobilises reserves. In veg it isn't.

Troubleshooting index Base nutrients

Iron deficiency

  • Interveinal yellowing on the newest growth with sharply defined green veins, often quite bright.
  • Almost always a pH problem rather than a shortage, iron availability collapses above about pH 6.3.
  • Usually has no necrotic spotting, which separates it from cal-mag.
  • Correct pH first and wait. Adding more iron to a high-pH tank does nothing.

Nutrient lockout guide pH Up & Down

Sulphur deficiency

  • Looks like nitrogen deficiency but appears on new growth instead of old, leaf age is the whole diagnosis.
  • Sulphur is immobile, so the plant can't move it out of older leaves to rescue the top.
  • Uncommon on complete nutrient lines, more likely on heavily supplemented or homemade mixes.

Troubleshooting index Base nutrients

Boron deficiency

  • The growing tip dies back and stems go brittle, corky or hollow. Nothing else looks quite like it.
  • Boron moves only with the transpiration stream, so low VPD and poor airflow cause it as often as a shortage.
  • Check VPD and airflow before adding boron, overdosing is toxic and the window is narrow.

Troubleshooting index Additives

Zinc deficiency

  • New leaves come out small and distorted, and internodes shorten so the top bunches into a rosette.
  • Like iron, usually a high-pH availability problem rather than an actual shortage.
  • Easy to confuse with broad mites, check under magnification before treating either.

Nutrient lockout guide Additives

Nutrient burn vs transplant shock

  • Nutrient burn shows as crispy, browning leaf tips and edges, typically starting on the oldest lowest leaves first.
  • Transplant shock shows as general wilting and slowed growth after moving a plant, without the crisped leaf-edge pattern.
  • The fixes are opposite: burn needs a flush and reduced feed, shock needs time and stable conditions, not less feed.

Burn vs shock guide Base nutrients

Light

Light burn

  • Bleached pale or white leaves and flower tips at the very top, worst directly under the fixture centre, following the light footprint rather than plant age.
  • Affected tissue usually stays pliable rather than going crispy, which separates it from nutrient burn.
  • More common under LED than HPS, because without radiant heat nothing warns you the light is too close.
  • Calcium deficiency is also worse near the light, so check for brown spotting before blaming intensity alone.
  • Raise the fixture or dim it. Judge the fix by whether new growth comes in clean.

Troubleshooting index Grow lights

Wind burn

  • Clawing, tattered or leathery edges on one side of the plant only, the side facing the fan.
  • Constant direct airflow strips moisture from leaf surfaces faster than the plant can replace it.
  • Fans should move air around the canopy, not blast at it. Aim across or above the plants.
  • Easy to misread as a nutrient problem, but the one-sided pattern gives it away immediately.

Troubleshooting index Fans & climate

Growth

Dead air inside the canopy

  • A dense canopy creates a pocket of still, humid air in the middle that your room readings never see.
  • Inner leaves yellow and die, and mould starts in the centre while the outside of the plant looks perfect.
  • Measure humidity inside the canopy, not just at the wall. The difference is often 10–15%.
  • Open the plant up, remove inner leaves that get no light, and add a fan that moves air through the canopy rather than over the top of it.
  • This is the single biggest preventable cause of bud rot in dense flowering plants.

Botrytis guide Clip fan

Poor flowering or fruit set

  • No flowers at all points to plant maturity, insufficient light, temperature stress, or excess nitrogen delaying reproductive growth.
  • Flowers that form then drop point to environmental or root-zone stress rather than nutrients.
  • Light is the main driver of flower development, under-lit plants set flowers that never fill.
  • Diagnose which stage is failing before changing your nutrient program.

Troubleshooting index Cal-Mag

Stretching and leggy growth

  • Light too weak, too far away, or unevenly distributed, so the plant grows upward searching for it.
  • Long thin stems with unusually large gaps between leaf sets rather than compact growth.
  • The stem that already stretched won't shorten back, but correcting conditions improves all growth from that point.
  • Some stretch at the start of flowering is normal for many crops, judge it against the first two weeks, not the whole cycle.

Stretching guide SANlight FLEX II

Leaves curling or clawing

  • Curling downward like claws most often points to nitrogen excess or overfeeding, especially with dark green foliage.
  • Curling upward can indicate heat stress or the light sitting too close.
  • Curling with crispy or browning edges usually means nutrient burn from EC running too high.
  • Curling combined with wilting points toward a root problem rather than the leaves.

Curling & clawing guide EC meter

Wilting despite water

  • Wilting despite adequate water almost always means roots can't take up that water, not that water is missing.
  • Low root zone oxygen is the most common cause, roots need oxygen to function, not just moisture.
  • Root rot, high EC and warm reservoir water are the three biggest reasons roots stop working.
  • Drooping leaves that feel firm and thick mean a wet root zone. Limp, papery leaves mean genuine drought.

Wilting guide O16 Stabilised Oxygen

Root bound

  • A plant that dries out unusually fast, stalls, and shows several mild deficiencies at once is often simply out of root room.
  • Roots circling the inside of the pot in a dense mat is the confirmation.
  • Every correction gives a small temporary improvement, which is what makes it confusing to diagnose.
  • Pot up rather than trying to feed your way out of it.

Troubleshooting index Pots & systems

Pests

Spider mites

  • Arachnids, not insects, so most standard insecticides have little effect.
  • Damage starts as pale or white speckling on upper leaf surfaces, the key difference from calcium deficiency, which always makes brown spots.
  • Check leaf undersides for mites, eggs and fine webbing. With a calcium problem you'll never find bugs or webbing.
  • Treat with a miticide, rotating products between applications so resistance doesn't build.
  • Spray during lights-off. They don't thrive above 60% RH or below 25 °C.

Spider mites guide Mite-Rid

Broad and russet mites

  • Too small to see without magnification, so growers usually chase nutrient problems for weeks first.
  • They live in the crevices of leaves, stems and flowers, and new growth goes glossy or wet-looking, twisted and blistered.
  • Damage concentrates at growing tips because that's where they feed. Older leaves stay normal.
  • If new growth is distorted and your numbers are in range, suspect these before anything else.
  • Treat the whole room, they move on air currents, hands and tools.

Troubleshooting index Pest control

Caterpillars, slugs and snails

  • Actual holes mean something is eating the plant. No deficiency or environmental problem makes holes.
  • Slugs and snails come out at night, leave scalloped-edge holes and slime trails.
  • Caterpillars leave dark frass pellets in leaf joints and inside flowers, and caterpillar damage inside a dense flower is a common starting point for grey mould.
  • Mostly a greenhouse and outdoor problem, but they get carried indoors on clothing and new plants.

Troubleshooting index Pest control

Diatomaceous earth for gnats

  • Only works while completely dry, and loses effect the moment media gets wet.
  • In an actively watered system the media is wet most of the time, which is why DE under-performs.
  • A moisture-resistant top dressing holds up far better.
  • Letting the top layer dry between waterings interrupts the larval lifecycle directly.

DE for gnats Gnat Nix

Fungus gnats

  • Adults are mostly a nuisance, the larvae in the media damage roots.
  • Let the top layer dry between waterings to break the larval lifecycle.
  • Combine sticky traps for adults with a larval treatment applied to the media at the same time.
  • Treating adults alone means the problem returns within days.

Fungus gnats guide Gnat Nix

Root aphids

  • The most commonly misdiagnosed pest in hydroponics, it looks exactly like a stubborn nutrient deficiency.
  • Plants go pale and stunted, feeding and pH corrections do nothing, and it slowly gets worse.
  • Check the root mass for small white waxy specks that look like mould but move.
  • If a deficiency won't respond to any correction, pull a plant and inspect the roots before changing anything else.

Troubleshooting index Pest control

Whitefly

  • Small white flies that lift in a cloud when the plant is disturbed, then settle again.
  • Nymphs on leaf undersides do the actual feeding damage and are easy to miss.
  • Honeydew leads to sooty mould, which blocks light and compounds the problem.
  • Yellow sticky traps tell you whether numbers are climbing or falling.

Troubleshooting index Pest control

Scale insects

  • Small raised bumps or a waxy coating on stems and leaves, easy to mistake for a plant feature.
  • Horticultural oil or insecticidal soap suffocates them on contact, coverage matters more than concentration.
  • Repeat every 7 to 10 days, since one application rarely gets every insect and egg.
  • Prune heavily infested stems rather than treating them in place.

Scale insects guide Pest control

Powdery mildew

  • Spores are in ambient air almost everywhere, so the goal is denying it the conditions, not excluding exposure.
  • Keep humidity below 50% during late flowering, when plants are most vulnerable.
  • Dense canopies hold humidity in the middle regardless of your room reading, airflow through the plant matters as much as the dehumidifier.
  • Treat at the very first white patches rather than waiting for spread, and rotate products between applications.

Powdery mildew guide Micro Kill

Aphids

  • Soft-bodied sap suckers that cluster on new growth and leaf undersides.
  • A botanical spray is one of the most effective natural treatments available in Australia.
  • Yellow sticky traps near the canopy catch winged aphids before a colony establishes.

Aphids guide Zero Tolerance

Mealybugs

  • White waxy powder with cottony egg masses, usually in leaf joints and along stems.
  • Diluted isopropyl on a cotton swab dissolves their protective wax on contact.
  • Check leaf joints and stem crevices carefully, they hide in gaps sprays miss.

Mealybugs guide Isopropyl alcohol

Thrips

  • Silvery streaking and distorted new growth usually show before you spot the insects.
  • Treat during lights-off and target leaf undersides where they shelter.
  • Blue sticky traps catch thrips more effectively than yellow.

Thrips guide Pest control

Grey mould (Botrytis)

  • Needs both high humidity and dead or dying plant matter to establish, and it starts inside the densest flowers where you can't see it.
  • Genetics play a major role, some lines are naturally resistant, others susceptible almost regardless of environment.
  • Keep humidity around 55% RH through late flowering. A realistic practical minimum for most spaces, not an extreme target.
  • Measure humidity inside the canopy, not at the tent wall, a dense plant holds its own microclimate.
  • Remove dead or dying leaves promptly, especially those touching flower sites, and check for caterpillar damage, which opens the door for it.

Botrytis guide Micro Kill

Pumps

Water pump not working

  • A humming pump that isn't moving water is usually an airlock or a jammed impeller, not a failed motor.
  • Mineral crystallisation from hard water builds up on the impeller and restricts flow gradually.
  • A pump left running dry, even briefly, can damage the seal.

Water pump guide Rio HF pump

DWC losing oxygen

  • A bad smell and declining plant health in a DWC bucket usually means dissolved oxygen has dropped low enough for anaerobic bacteria to take hold.
  • Check the air stone for clogging first, a partially blocked stone reduces output well before it fails completely.
  • Increasing air pump output and dropping reservoir temperature both raise dissolved oxygen directly.

DWC guide Air stones

Air stone not bubbling

  • A blocked air stone is the most common cause, mineral scale and biofilm clog the pores that create bubbles.
  • Kinked or pinched airline cuts off flow before it reaches the stone.
  • A reversed or stuck check valve can block airflow entirely even with the pump running.
  • A pump underpowered for the depth the stone sits at can't push air down against that pressure.

Air stone guide Air stones

Reservoir

Reservoir turning green

  • Green water means algae, and algae needs light reaching the solution to establish.
  • Common light leaks: lid edges that don't seal flush, net pot gaps, clear tubing, sight tubes, light-coloured walls.
  • Full light exclusion is the actual fix. Cleaning without sealing the leak means it's back within days.
  • Use opaque reservoirs, opaque tubing and a properly sealed lid.

Algae & light leaks Opaque reservoir

Sterile or bioactive

  • Sterile uses oxidisers to suppress microbial activity broadly. Bioactive introduces beneficial bacteria or fungi to the root zone.
  • Oxidisers aren't selective, they don't distinguish pathogens from the beneficials you're trying to establish.
  • Don't introduce beneficial bacteria while an active oxidiser is present.
  • Pick one primary strategy and only switch between cycles, with proper cleaning in between.

Sterile vs bioactive Guardian Hydro Clean

Biofilm in the lines

  • Attached microbial and organic buildup inside wet tubing, drippers and fittings, not floating loose in the reservoir.
  • Signs: uneven flow between outlets, gradually declining flow, slippery internal residue, an off smell.
  • Far more common in recirculating systems, where the same solution passes the same surfaces repeatedly.
  • Isolate the affected section rather than running strong chemicals through lines connected to living roots.

Troubleshooting index Fittings & drippers

Reservoir too hot

  • Above 22 °C dissolved oxygen starts dropping. Above 26 °C Pythium can establish within 24 to 48 hours.
  • The biggest heat sources are the grow light, ambient room temperature, and the pump running inside the reservoir.
  • Moving the reservoir out of direct light, insulating or shading the tank, and increasing aeration all help without a chiller.
  • Frozen bottles work but swing temperature several degrees each cycle, and that swing is its own stressor.
  • A dedicated chiller is the reliable fix if heat is persistent rather than an occasional summer spike.

Reservoir cooling guide Opaque reservoir

Propagation

Damping off

  • A fungal collapse right at the media line, a thin, water-soaked stem is the tell.
  • Driven almost entirely by excess surface moisture and poor airflow, not the nutrient program.
  • Once a seedling has collapsed at the stem it cannot be saved. Prevention matters far more than treatment.
  • A gentle circulation fan across seedling trays is one of the most effective single preventions.

Damping off guide Clip fan

Match strength shows how strongly your inputs point at each cause relative to the others, it is not a probability. Greyed reasons are evidence pointing away from a cause. The layer tag follows the order worth working in: environment first, then hydration and root zone, then chemistry, then nutrition. Guidance only, not a guaranteed diagnosis.

-
confidence -
-