Hydroponics 101
The short version of what a vertical tower needs: water + dissolved nutrients, oxygen at the roots, light, and a stable temperature. Everything else is detail.
How a vertical tower works
The tower in these notes (see The Tower) has a submersible pump in a 40+ L pot at the base. The pump pushes solution up a 20 mm center pipe to a sprinkler head at the top, and it rains down through the stack of grow pots, past the roots of plants held in net cups, and drains back through the pot floors into the reservoir. Roots get water, air, and a shallow standing layer in each pot between cycles; one commenter on the model found roots look healthier this way than in designs that drain dry.
A bigger reservoir is more forgiving: pH and nutrient concentration drift more slowly. This design’s 40+ L pot is a good size.
How often to run the pump
The model page gives no pump schedule, and the designer calls the system low-maintenance, so treat these as starting points borrowed from university-extension trickle towers, then adjust by watching the roots:
| Stage | Pump schedule (lights on) | Notes |
|---|---|---|
| Seedlings just transplanted | 15 min on / 15 min off | Roots are short; keep them damp |
| Established plants | 15 min on / 30–45 min off | Cut back if the cups stay soggy or algae shows |
| Lights off | Keep cycling, e.g. 15 min on / 45 off | Don’t leave a trickle tower dry overnight; the pump runs 24 h on its own timer, separate from the light timer |
Use a plain mechanical or digital outlet timer. Watch the roots, not the clock: white and fuzzy is healthy; slimy, brown, or smelling bad means too wet, too warm, or too little oxygen. Wilting at midday with a dry cup means run it more often.
A pump that fails while the lights are on can kill a tower in hours, so check it the first thing every day.
Feeding: pH and EC
- pH — keep the solution at 5.5–6.5 (aim ~5.8–6.0). Outside that range, plants cannot take up some nutrients even though they are in the water.
- EC (electrical conductivity, how strong the nutrient mix is) — the one number that tells you when to add nutrients. Measured in mS/cm.
| Crop group | pH | EC (mS/cm) |
|---|---|---|
| Lettuce, arugula, bok choy | 5.5–6.5 | 1.2–1.6 |
| Basil, other herbs | 5.5–6.5 | 1.0–1.6 |
| Kale, chard | 5.5–6.5 | 1.2–2.0 (the same solution as lettuce works) |
| Strawberries | 5.5–6.2 | 1.8–2.2 |
| Dwarf tomatoes | 5.8–6.3 | 2.0–4.0 |
| Peppers | 5.8–6.3 | lower than tomatoes, roughly 0.8–1.8 |
Start seedlings at roughly a quarter to half strength and work up. (Commercial growers feed seedlings at full strength; weak is the cautious choice for a first run.)
Routine for a small tower:
- Daily — look at the tank level and the roots. Top off with plain water (plants drink water faster than nutrients, so topping off with plain water keeps EC from creeping up).
- Daily for the first few weeks, then every 2–3 days once readings are stable — check pH and EC at the same time of day. Adjust pH after measuring EC. Adjust pH with small doses of pH-down (or up); add nutrients if EC has dropped below target.
- Every 2 weeks — drain, rinse, and refill the whole reservoir with fresh solution. Top-offs cannot fix an unbalanced mix.
- As needed — wipe slime off the pump intake and any drip points.
Use a complete hydroponic nutrient (two- or three-part) rather than garden fertilizer, and follow its label for the dilution. Miracle-Gro and similar lawn-and-garden products are not formulated for this.
Water temperature (important in a garage)
Keep the reservoir around 68–72 °F; treat 75 °F as the ceiling. Warmer water encourages root rot (often Pythium) and holds less oxygen; much colder water slows growth. In an unheated garage in winter, the problem is cold, not hot — see Garage Grow Setup.
Good first crops
| Crop | Why it works | Roughly seed to first harvest |
|---|---|---|
| Loose-leaf and butterhead lettuce | Fast, low EC, tolerates cool temperatures; cut-and-come-again | 5–8 weeks |
| Basil | Loves the tower, lots of leaf; needs warmth | 5–7 weeks |
| Arugula, bok choy | Fast and forgiving | 4–6 weeks |
| Kale, Swiss chard | Cold tolerant; good for a cool garage | 6–8 weeks |
| Mint, parsley, cilantro | Mint grows like a weed (give it its own spot); cilantro bolts quickly | 6–10 weeks |
| Strawberries (day-neutral) | A reasonable second project; buy bare-root crowns, not seed | months |
The tower is built for more (the designer lists tomatoes, cucumbers, broccoli, kohlrabi, peppers, and eggplant, with an optional ring support for heavy crops) and offers three pot sizes: GrowBig4 for large crops, Grow8 for radishes and small salad, GrowSmall4 for head lettuce, herbs, and flowers. For a first winter in a garage, fill it with the leafy crops above: fruiting crops need much stronger light and more heat than a winter garage gives them. Dwarf cherry tomatoes and peppers are a step-two project once the routine is working.
Common problems
| Symptom | Likely cause |
|---|---|
| Pale new leaves | pH out of range, or EC too low |
| Brown, slimy roots | Water too warm or low dissolved oxygen (root rot, often Pythium) |
| Brown leaf tips on lettuce | Usually a calcium-delivery problem from fast growth under strong light with poor airflow: add a fan and ease the light. Very high EC causes a different, general leaf-edge burn |
| Algae in the tank or on the cups | Light reaching the solution; cover the tank and use opaque parts |
| Tall, floppy plants | Light too weak or too far away |
| Lettuce bolting (flower stalk) | Heat or very long days |
Safety
Water and mains power share a space. Plug everything into a GFCI-protected outlet, use drip loops on cords, and keep power strips and timers well above the reservoir.