# Low-pressure aeroponics (LPA)

> LPA uses an ordinary submersible pump and spray heads to drench roots hanging in a dark chamber with coarse droplets. It is essentially a spray-assisted hydro system: forgiving (a pool on the chamber floor keeps roots wet for hours), cheap, and easier than true high-pressure aeroponics. Run sprays continuously or on short cycles such as 1 minute on, 4 off, with a chamber humidity watchdog and solution at 18–22 °C.

- Canonical: https://genetixbay.com/knowledge/systems/lpa-aeroponics.html
- Category: Systems · Level: Intermediate
- Evidence: Supported · Status: Draft: awaiting expert review (some figures are being checked)
- Stage: Veg, Flower · Systems: Aeroponics
- Updated: 2026-10-31 · Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay Knowledge Base (genetixbay.com/knowledge)"

## Questions and answers

**What is low-pressure aeroponics?** Low-pressure aeroponics is a hydro system in which an ordinary submersible pump feeds 360° sprayers or a spray bar inside a dark root chamber, drenching hanging roots with large droplets of hundreds of micrometres. [True aeroponics](https://genetixbay.com/knowledge/glossary/hpa.md) research uses much finer droplets of about 10–100 µm made at high pressure, so low-pressure aeroponics is better described as spray-assisted hydroponics.

**LPA vs HPA: which is better?** Low-pressure aeroponics is the better choice for most growers because it is cheaper and far more forgiving: the pool on the chamber floor keeps roots wet for 1–4 hours if the pump fails. High-pressure aeroponics makes a true 10–100 µm mist and outstanding roots, but roots can be harmed in tens of minutes. No published study compares their cannabis flower yields.

**What spray cycle for low-pressure aeroponics?** Low-pressure aeroponics usually sprays continuously or on a short cycle such as 1 minute on and 4 minutes off, a grower setting to verify for your chamber. Spray continuously for clones until roots are well developed. Keep chamber humidity at about 95–100% during the cycle with a humidity watchdog, and keep the solution at 18–22 °C (64–72 °F).

**Why do my aeroponic sprayers keep clogging?** Aeroponic sprayers clog with fertiliser salts and root fragments. Fit a fine screen on the pump intake, run a daily plain-water spray cycle to [flush](https://genetixbay.com/knowledge/glossary/flushing.md) the lines, keep roots from wrapping the sprayers, and clean the heads between runs with a dilute acid soak and a rinse, wearing gloves and goggles. A slow fall in chamber humidity or dry root patches signals a clog.

**Short answer.** A standard submersible pump feeds 360° sprayers or a spray bar inside a closed, dark root chamber. Droplets are **large (hundreds of µm)**, so the chamber is a constant drizzle rather than a mist [4]. True aeroponics researchers work with much finer droplets, roughly 10–100 µm, produced at high pressure [1]. LPA is forgiving: the pool on the chamber floor keeps roots wet, so a pump failure buys **1–4 hours** [4]. Spray **continuously, or ~1 min on / 4 min off** with a humidity watchdog; solution **18–22 °C (64–72 °F)** [3][4].

## Numbers that matter

| Parameter | Target | Notes |
|---|---|---|
| Spray cycle | Continuous, or 1 on / 4 off | [4] |
| Chamber [RH](https://genetixbay.com/knowledge/glossary/relative-humidity.md) | ~95–100 % during cycle | Falling RH = clog or pump issue |
| Solution temperature | 18–22 °C (64–72 °F) | Pump heat warms the reservoir |
| [pH](https://genetixbay.com/knowledge/glossary/ph.md) / [EC](https://genetixbay.com/knowledge/glossary/ec.md) | pH 5.6–6.0; EC as [DWC](https://genetixbay.com/knowledge/glossary/dwc.md) | |
| Filter | Fine screen on pump intake | Sprayers clog with salts and roots |
| Daily line flush | Plain water spray cycle | Jardin default [4] |

## How to run it

1. Light-proof chamber; sprayers that cover every [root zone](https://genetixbay.com/knowledge/glossary/root-zone.md); [drainage](https://genetixbay.com/knowledge/glossary/runoff.md) back to the reservoir.
2. Start clones in neoprene collars or small [net pots](https://genetixbay.com/knowledge/glossary/net-pot.md); spray continuously until roots are well developed.
3. Keep roots from wrapping sprayers; trim if needed.
4. Clean sprayers between runs (dilute acid soak, rinse; gloves and goggles).

## Failure modes

| Problem | Sign | Jardin response [4] |
|---|---|---|
| Pump dead | RH falls | Alert; LPA buys hours |
| Sprayer clogs | Slow RH decline, dry patches | Daily flush cycle; clean heads |
| Chamber overflow | Float trips | Pump off |
| [Root rot](https://genetixbay.com/knowledge/glossary/root-rot.md) | Brown roots | Cool solution; sanitation |

## Jardin notes

Jardin method "LPA": chamber RH/temperature, pump current, reservoir mass and chamber overflow float; spray scheduler with RH watchdog. Time-to-harm 1–4 h. Automation level 3 [4].

## Common mistakes

- Calling LPA "aeroponics" and expecting HPA root behaviour.
- No intake filter.
- Warm reservoir from a submerged pump in a small tank.

## Evidence

Aeroponics as a method is *Established* in the literature [1]; cannabis roots grow vigorously in aeroponics (13- to 64-fold more root [dry weight](https://genetixbay.com/knowledge/glossary/dry-weight.md) than soil in one study focused on root products) [2]. Head-to-head LPA vs other systems for cannabis flower yield is not published; LPA settings are *Grower practice*.

## Sources

1. Lakhiar IA, Gao J, Syed TN, Chandio FA, Buttar NA, 2018. Modern plant cultivation technologies in agriculture under controlled environment: a review on aeroponics. Journal of Plant Interactions 13(1):338–352. https://doi.org/10.1080/17429145.2018.1472308
2. Ferrini F, Fraternale D, Donati Zeppa S, et al., 2021. Yield, characterization, and possible exploitation of Cannabis sativa L. roots grown under aeroponics cultivation. Molecules 26(16):4889. https://pmc.ncbi.nlm.nih.gov/articles/PMC8401984/
3. Colorado State University Extension PlantTalk 2043. Root disease problems and management in hydroponic systems. https://planttalk.colostate.edu/topics/miscellaneous/2043-root-disease-problems-management-hydroponic-systems/
4. GenetixBay Jardin engineering notes, 2026 (system profiles and failure margins).