# No fresh white root tips: likely causes and fixes

> No fresh white root tips on cannabis is most often Low dissolved oxygen in the root zone, Chlorine or chloramine in tap water harming roots and soil life or Pump, timer, air or emitter failure in a hydro, aero or drip system. How to tell them apart, the fix for each and what recovery looks like.

Also called: roots not growing, no new roots, roots stopped growing, roots look old.

Run the checker with this sign: https://genetixbay.com/knowledge/diagnose/?at=roots&s=no-new-root-tips

## Likely causes, most likely first

### Low dissolved oxygen in the root zone (Possible)

- Kind: Root zone; urgency: Act within a day or two
- Fix: Restore oxygen: clean or replace air stones, size the air pump for at least ~1 L/min per 4 L, keep a 2-5 cm air gap under net pots once roots reach the water, cool the solution to 18-22 °C (64-72 °F). Aim for 6-8+ mg/L DO.
- Recovery: Fresh white root tips within 3-5 days; wilting stops.
- Confirm: Dissolved oxygen check: Measure DO with a meter in the root zone, or check the system: air pump running, stones bubbling evenly, return water splashing, no dead spots. Target 6-8+ mg/L. Without a meter: if stones are clogged or the pump is undersized for the volume, assume low DO.
- Confirm: Measure reservoir and root-zone temperature at the end of the light period: Measure the solution in the reservoir and in the root chamber or bucket, at the warmest time of day. Target 18-22 °C (64-72 °F). Above about 23-24 °C (73-75 °F), dissolved oxygen falls and Pythium risk rises; below 16 °C (61 °F) uptake slows.
- Confirm: Look at the roots: Hydro: lift the net pot and look at the root mass in good white light. Containers: tip the plant out with a hand over the medium and look at the edges and bottom of the root ball. Healthy roots are white to cream with fine fuzzy tips. Brown roots whose outer layer slides off between the fingers leave a bare thread: rot. Firm, evenly tan roots with white tips in coloured solution are staining.
- Confirm: Check pumps, timers, nozzles and drippers: Watch one full cycle: the pump starts on time, every nozzle mists or every dripper delivers, NFT channels have flow end to end, air stones bubble. Clear clogged emitters and filters. In HPA, a failed pump or blocked nozzle can kill exposed roots fast, so check this first when plants on one system wilt together.
- Article: [Deep water culture (DWC)](https://genetixbay.com/knowledge/systems/dwc.md)

### Chlorine or chloramine in tap water harming roots and soil life (Less likely)

- Kind: Root zone; urgency: Low urgency
- Fix: Usual tap levels rarely hurt the plant directly; the concern is living soil, beneficial microbes and young roots. Chlorine gasses off in 24 h of aeration; chloramine does not. Remove chloramine with long-contact or catalytic carbon, or about 1 g of ascorbic acid per 100-400 L, or use RO.
- Recovery: Biology recovers over weeks; seedlings resume growth within a week.
- Confirm: Get a water report (or test your water): Ask your water utility for the annual report or test well water: alkalinity (mg/L CaCO3), pH, EC, Ca, Mg, Na, Cl, B, and whether it uses chlorine or chloramine. Alkalinity above ~100-150 mg/L as CaCO3 pushes root-zone pH up; sodium above ~50 mg/L and chloride above ~70 mg/L are a problem; softened water is high in sodium.
- Article: [Water quality for cannabis: RO vs tap, alkalinity, bicarbonates and chloramine](https://genetixbay.com/knowledge/ph-ec/water-quality.md)

### Pump, timer, air or emitter failure in a hydro, aero or drip system (Less likely)

- Kind: Root zone; urgency: Act now
- Fix: Restore flow or air immediately: check power, timer, float switches, filters and nozzles. Mist exposed roots by hand or lower plants into solution while you fix it. In HPA and NFT, fit an alarm and a backup pump; roots die fast when misting or flow stops.
- Recovery: Plants regain turgor within hours if roots were not dead; brown, collapsed roots mean rot risk next.
- Confirm: Check pumps, timers, nozzles and drippers: Watch one full cycle: the pump starts on time, every nozzle mists or every dripper delivers, NFT channels have flow end to end, air stones bubble. Clear clogged emitters and filters. In HPA, a failed pump or blocked nozzle can kill exposed roots fast, so check this first when plants on one system wilt together.
- Article: [High-pressure aeroponics (HPA)](https://genetixbay.com/knowledge/systems/hpa-aeroponics.md)

## Note

Guidance, not a guarantee. The checker weighs common causes against what you tell it; confirm with the tests before you treat, change one thing at a time and watch the new growth.