Common Problems: Tip Burn, Algae, Root Issues

Most hydroponic failures come from the same three issues: tip burn, algae, and root rot. This guide shows you how to diagnose each one from what you see on the plants and system, then walks you through the exact fixes and hardware tweaks to stop it coming back.

6 min read

Most hydroponic crops fail for the same three reasons: tip burn, algae, and root issues. The symptoms look different, but they all come back to how you manage water, nutrients, and the root environment. This guide gives you a fast way to identify the problem, fix it now, and stop it from coming back.

Hydroponic lettuce in an NFT system showing early tip burn on the center plant, with clean white channels and LED grow lights above.

Step 1 Quick Diagnosis

Match what you see to the descriptions below, then jump to the right section.

What you see Most likely issue Check first Fix section
Leaf edges dry, brown, or crispy. Centers still green. Tip burn (calcium delivery issue). , pH, airflow, temperature in the canopy. Step 2: Fix tip burn
Green or brown slime on channels, tank walls, or media surface. Algae. Any light hitting nutrient solution, warm spots, dirty tank or channels. Step 3: Stop algae
Roots turning beige to brown, slimy texture, bad smell. Plants wilt even in wet media. Root disease / low oxygen. Root color & smell, solution temperature, aeration, drift in and pH. Step 4: Rescue roots

Step 2 Fix Tip Burn

Tip burn shows up most in fast-growing leafy greens (lettuce, basil, brassicas). It’s rarely a “no calcium in the tank” problem; it’s almost always a calcium transport problem inside the plant.

Macro close-up of lettuce crown showing severe calcium tip burn with brown, dried inner leaf edges.

How tip burn looks

  • Brown, dry, or translucent edges on young inner leaves.
  • Outer leaves can still look decent, so damage hides in the core.
  • Plants may still be growing fast, just with ugly centers.

Why it happens

Calcium moves with water. Anything that reduces water flow to new leaves causes tip burn:

  • High humidity + poor airflow: low transpiration = poor calcium delivery.
  • Hot canopy: growth outpaces calcium transport.
  • too high: roots struggle to take up water.
  • pH out of range: calcium is present but less available.
  • Genetics: some cultivars are very tip-burn prone under stress.

Immediate actions

  1. Lower EC slightly (for leafy greens).
    • Target EC around 1.0–1.6 for lettuce and similar greens.
    • If you’re already high for the crop, drop EC by about 0.2–0.3 and watch new growth.
  2. Bring pH into the calcium “sweet spot”.
    • Keep pH roughly 5.5–6.2 for mixed greens.
    • Avoid shock adjustments; correct in small steps.
  3. Increase airflow through the canopy.
    • Add or redirect fans so leaves gently move everywhere in the system.
    • Remove dead-air pockets behind tanks, under benches, and between channels.
  4. Control heat and humidity.
    • For lettuce: aim for ~20–23 °C (68–73 °F) in the crop zone.
    • Try to avoid sitting above 75–80% all day.
  5. Confirm your calcium source.
    • Make sure your program includes calcium (commonly calcium nitrate).
    • Keep calcium stock separate from phosphates/sulfates to avoid precipitates.

Preventing tip burn on future runs

  • Use tip-burn tolerant lettuce / leafy cultivars for warm or humid environments.
  • Log , pH, temp, and daily. Tip burn usually follows a pattern.
  • Size fans and vents so you can turn airflow up when growth is at peak speed.
  • Don’t stack high light, high EC, and high temperature unless your environment is tightly controlled.

Step 3 Stop Algae Before It Spreads

Algae is what you get when nutrient solution, light, and warm temperatures meet. It steals oxygen, clogs hardware, and builds that shelters pathogens.

Side-by-side hydroponic troughs showing heavy green algae buildup in the contaminated channel and a fully cleaned white channel next to it.

How algae looks

  • Green or brown slime on channels, lids, tank walls, or media surface.
  • Slippery feel on any surface that gets wet regularly.
  • Water surface looks filmy or has floating mats.
  • Emitters and drippers clog more often than they should.

Core causes

  • Light leaks: any clear/transparent plastic or uncovered solution.
  • Warm solution: warm water + nutrients = rapid algae growth.
  • Stagnant zones: slow-moving corners of tanks or channels.
  • Organic load: dead roots, leaf bits, media fines feeding growth.

Immediate actions

  1. Block light from the nutrient solution.
    • Use opaque lids on reservoirs; no clear totes.
    • Cover any open channels or troughs.
    • Swap clear tubing for opaque (black or white) where possible.
  2. Physically remove algae.
    • Drain and scrub channels, lids, and tank walls between crops.
    • Use a suitable cleaner or sanitizer, then rinse thoroughly.
  3. Improve circulation.
    • Add a small circulation pump in large tanks to keep water moving.
    • Check slopes so solution doesn’t pool in low spots.
  4. Manage nutrient temperature.
    • For leafy greens, target ~18–22 °C (64–72 °F) solution temperature.
    • Shade tanks and lines; avoid running pipes where they bake in the sun.

Notes by system type

  • : Light entering through planting holes is the usual starting point. Use net pots or collars that actually shade the nutrient film.
  • : Large exposed surfaces are algae magnets. Tight-fitting, opaque lids are mandatory, not optional.
  • Drip / Dutch buckets / grow bags: Cover the media surface so light doesn’t hit wet substrate (discs, mulch, or fitted lids).

Step 4 Rescue and Protect Roots

Roots are the part of the plant you see the least and lose the most money to. Healthy roots are white to cream, firm, and neutral smelling. Anything trending toward brown, slimy, and foul is a problem you need to treat quickly.

Hand holding two hydroponic lettuce plants above a DWC reservoir, comparing healthy white roots to brown, slimy roots damaged by disease.

How root problems look

  • Roots go from white/cream to beige, then tan, then dark brown.
  • Texture shifts from crisp to soft or slimy.
  • Reservoir or roots smell sour, swampy, or rotten.
  • Plants wilt even though the media is clearly wet.
  • Growth stalls; older leaves yellow from the bottom up.

Core causes

  • Low in solution, especially when warm.
  • Pathogens like in recirculating setups.
  • Chronic overwatering in media systems with poor drainage.
  • High organic load from dead roots, algae, and debris.

Immediate actions

  1. Check solution temperature.
    • Consistent readings above ~23–24 °C (73–75 °F) push you toward root problems.
    • Short term: shade tanks, increase airflow, and remove any heat sources near plumbing.
  2. Increase aeration and circulation.
    • Add or upsize air pumps and stones in or main reservoirs.
    • Make returns splash into the tank instead of trickling to boost oxygen.
  3. Remove the worst plants.
    • Plants with mostly rotten roots should be culled so they stop feeding the problem.
  4. Clean and refresh when infection is widespread.
    • Drain, clean, and sanitize tanks, channels, and plumbing between crops.
    • Start with fresh nutrient solution instead of trying to “fix” a dirty one forever.

Notes by system type

  • : Lives and dies on aeration. Undersized air pumps or clogged stones = slow death.
  • : Long runs and warm rooms mean the solution at the far end is the warmest and lowest in oxygen. That’s where problems show first.
  • Drip / Dutch buckets / grow bags: Too many short irrigations can keep media constantly saturated. You want moist, not anaerobic.

Preventing root issues run after run

  • Size pumps, air stones, and plumbing for your peak plant load, not the day you start up.
  • Keep solution temperature and dissolved oxygen in a realistic range for your crop, not for your comfort.
  • Stop letting dead roots and algae accumulate in tanks and channels “for later”. They’re food and shelter for problems.
  • Make a real sanitation step part of your crop cycle plan, not an emergency response.

Still fighting the same problems every cycle?

Share your system type, reservoir size, and main crop. We’ll help you spot weak points in your design and point you to hardware that keeps EC, pH, temperature, and oxygen in the safe zone.

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Further reading

These guides connect directly to the same root causes behind tip burn, algae, and root health. If you haven’t read them yet, they’ll fill in the gaps fast:

EC (Electrical Conductivity)

A measure of how much dissolved fertilizer is in your nutrient solution. Higher EC = more concentrated solution. Used as a fast proxy for overall nutrient strength.

Biofilm

A slimy layer of microorganisms and organic matter that sticks to wet surfaces in your system. It protects algae and pathogens and reduces flow through pipes and emitters.

Pythium

A water-borne pathogen that causes root rot in hydroponics. It thrives in warm, low-oxygen, dirty nutrient solutions and spreads quickly in recirculating systems.

NFT (Nutrient Film Technique)

A hydroponic system where a thin film of nutrient solution flows along a slightly sloped channel, bathing the roots while keeping plenty of air around them.

DWC (Deep Water Culture)

A hydroponic method where plant roots hang directly into a reservoir of aerated nutrient solution, relying on strong air pumps and stones for oxygen.

RH (Relative Humidity)

The amount of moisture in the air compared to the maximum it can hold at that temperature. High RH reduces transpiration and can worsen tip burn.

Dissolved Oxygen

The oxygen held in your nutrient solution. Roots need it to respire; low dissolved oxygen, especially in warm water, leads quickly to root stress and disease.

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