⏳ 17 min read · Last updated: September 2026
A one reservoir hydroponic salad garden is the simplest way to keep two people in fresh leaves every week. Instead of a row of jars, each with its own pH reading and its own fill line, you run one opaque tote with six plants in the lid. You test once, top off once, and change the water once. The trick is choosing crops that are happy on the same water, and replanting on a rhythm so the tank never empties all at once.
This guide is the plan for that tank: which system to use, which crops share a reservoir well, how strong to mix it, where the light goes, and a planting calendar that gives you a salad every week. If you have never grown anything hydroponically, the apartment hydroponics beginner’s guide is a gentler first read.
The One Reservoir Hydroponic Salad Plan in Brief
- Use an aerated tote (DWC) for a salad you keep replanting. A Kratky tote suits one batch planted at once, but it cannot take new seedlings beside rooted plants.
- Build the tank around lettuce, then add arugula, basil or parsley. Mint, spinach and cilantro each need their own container.
- Run the shared solution at EC 1.5 and hold the pH near 6.0, which sits inside the range of every crop in the tank.
- Give it 14 hours of light a day with the panel 6 to 8 inches above the leaves, and keep the water at 65 to 75°F (18 to 24°C).
- In the aerated tote, top off daily with plain pH-adjusted water, change the whole reservoir every 2 weeks, and sow two new lettuce plugs every 3 weeks.
The Numbers for the Shared Tank
These are the settings for the whole tank, so every crop in it has to be happy with them.
DWC or Kratky for a Shared Salad Tank
Both systems can grow a tote of salad. They suit different plans, and choosing the wrong one is the most common reason a shared tank fails.
A Kratky tote is filled once, and the plants drink the level down. As it falls, a layer of air opens between the solution and the lid, and the upper roots breathe in it. That works beautifully for a batch planted on the same day, because every plant’s roots follow the level down together. It is the ideal first tote, and the Kratky tote setup guide walks through one. Kratky’s own lettuce method budgets 1.5 to 2 gallons of solution per plant, so a batch of six wants a big bin.
Why a Rolling Salad Needs an Air Stone
A weekly salad is different, because you keep pulling old plants and dropping in new seedlings. A new seedling needs the solution touching the bottom of its cup. Meanwhile, the plants beside it have spent weeks growing roots into the air layer, and raising the level for the newcomer drowns them. So a Kratky tote cannot be replanted a few cups at a time.
DWC solves that. The water stays at one level, just under the cups, and an air stone keeps it full of oxygen, so old and new plants live side by side. The price is a small air pump. It hums, but on a folded towel or a foam pad, and away from the bedroom, most people stop hearing it within a day. The quiet air pump roundup compares the quietest ones, and DWC vs Kratky for apartments sets out the trade-offs in full.
- Want silence and happy to plant in batches? → a Kratky tote, replanted all at once when the batch is done
- Want a salad every week without gaps? → an aerated tote, replanted two cups at a time (the plan below)
- Short on counter space? → two or three jars of lettuce on a sunny windowsill may be enough
Building the Tank
The tank itself is a storage tote with holes in the lid. For six plants, choose an opaque tote that holds several gallons and sits steady on the counter or a shelf. Clear or thin plastic lets light through, and light in the water grows algae within days, so wrap anything see-through in foil tape or paint.
- An opaque tote with a flat lid that is stiff enough not to sag
- Six 2-inch net cups and a 2-inch hole saw
- An air pump, tubing, a check valve and one air stone
- Rockwool cubes or plugs for starting seed, plus clay pebbles to hold the cubes
- A pH meter and an EC meter, since one tank means one reading for everything
- A leak tray underneath, because it is cheap insurance in a rental
Lay out the holes in two staggered rows of three, so no plant sits directly in another’s shadow. Keep 6 to 8 inches between lettuce and basil, which grow wide, and 4 to 6 inches for arugula and parsley. Sand the cut edges smooth, so roots do not snag when you lift a cup out.
Mount the air stone in the middle of the floor and run the tubing through a small notch at the back of the lid. Put the check valve in the line, because it stops water siphoning back into the pump if the power goes off. Stand the tote on a leak-safe tray or mat, and the shopping list builder puts the whole kit together if you would rather tick boxes.
Which Crops Share One Reservoir
Everything in the tank drinks the same water, so the crops have to agree on pH, feed strength, light hours and temperature. Lettuce is the anchor. It grows fast, forgives mistakes, and gives you outer leaves 4 to 5 weeks from seed and full heads at 7 to 8 weeks. The rest are chosen to fit around it.
| Crop | Its own EC | First harvest | In the shared tank? |
|---|---|---|---|
| Lettuce | 1.0 to 1.4 | Outer leaves at 4 to 5 weeks from seed | Yes, because it anchors the tank |
| Arugula | 1.4 to 1.8 | 30 to 40 days | Yes, especially when the room stays cool |
| Basil | 1.0 to 1.6 | 5 to 6 weeks from seed | Yes, though it needs regular pinching |
| Parsley | 1.4 to 1.8 | 6 to 8 weeks | Yes, since one plant lasts for months |
| Mint | 2.0 to 2.4 | 4 to 5 weeks from a rooted cutting | No, because it wants a much stronger feed and its roots take over |
| Spinach | 1.4 to 1.8 | 35 to 45 days | No, since it needs 12 hours of light and colder water |
| Cilantro | 1.4 to 1.8 | 6 to 8 weeks from seed | Better in its own jar, although the feed matches, because it bolts in a warm tank |
Pair the Crops by Room Temperature
Temperature decides the final mix more than feed does. Arugula and lettuce are happiest in a cool room, and arugula in particular bolts quickly once it runs warm. Basil and parsley like the warmer end. So in a room that rarely passes 70°F (21°C), fill the tank with lettuce and arugula. In a warmer flat, run lettuce with basil and parsley, and give arugula a miss until autumn.
What Stays Out of the Tank
Mint is the hardest no. It wants EC 2.0 to 2.4, which would burn the lettuce, and its roots form thick ropes that wrap around everything else in the water. Give it a jar of its own. Spinach needs 12 hours of light rather than 14, and water at 59 to 68°F, so it cannot share a lamp or a tank with this crew. Cilantro would accept the feed, but it is an advanced crop that bolts fast in warm water, so it does better in its own jar in the coolest spot you have. The best herbs for small hydroponics covers each of these in its own right.
Mixing One Solution for Everything
A shared tank runs on a compromise. At EC 1.5, lettuce is fed a little above its own range but rarely burns, while basil, arugula and parsley get enough to grow well. If the tank is mostly lettuce, you can run it at lettuce’s own 1.0 to 1.4 instead, and the herbs will simply grow a little slower. Hold the pH near 6.0. That sits inside the range of every crop in the tank, so a small drift in either direction does no harm.
- Fill the tote with water at room temperature. If your tap water is very hard or very soft, using tap water for hydroponics explains what to adjust.
- Add part A, stir well, then add part B and stir again. Never pour the two concentrates together undiluted.
- Check the EC and bring it to 1.5, either with a little more concentrate or with plain water.
- Check the pH last and adjust toward 6.0, because the nutrients themselves move it.
The pH and nutrient calculator works out the doses for your tote size, and mixing two-part nutrients shows the method step by step. If the EC ends up too high, lowering EC safely is the fix.
The Daily and Two-Week Routine
Every day, top the tank back up with plain water adjusted to pH 6.0, never with nutrients. Plants drink water faster than they use the salts in it, so feeding at every top-off pushes the strength up week by week. The top-off guide explains the reasoning. Every 2 weeks, change the whole reservoir. Lift the lid, with the plants still in it, onto a tray, empty and rinse the tote, refill it with fresh solution, and put the lid back. The two-week rule covers why that interval works.
Light and Temperature
A tote of salad needs a real grow light. Hang the panel 6 to 8 inches above the tops of the leaves and put it on a timer for 14 hours on and 10 off. Raise it as the plants grow, so the gap stays the same. Those inches are a starting point for a typical home LED, and the leaves tell you whether it is right: stretching and pale means lower, bleached or crisp edges mean higher.
In intensity terms, lettuce does well at about 240 to 340 PPFD at 14 hours, and basil and the other herbs are happy in the same band. A countertop LED of 20 to 36 real watts per 2-foot footprint usually covers a tote this size. The grow light calculator checks whether your fixture reaches the corners, and one light over basil, mint and lettuce explains how to keep a mixed canopy even. A plug-in timer from the compact timers roundup keeps the 14 hours honest.
Keeping the Water Cool
The water should stay at 65 to 75°F (18 to 24°C). Above 72°F (22°C) the air stone matters more, and above 75°F (24°C) root rot becomes a real risk. A tote under a lamp in a summer kitchen warms up, so keep it off the top of the fridge and out of direct afternoon sun. Never drop ice into the reservoir. The sudden cold shocks the roots and the effect fades within an hour. Instead, stand a frozen bottle against the outside of the tote, or move the whole setup somewhere cooler. Small system temperature problems has more fixes for a warm flat.
A Planting Calendar for a Weekly Salad
The point of the plan is that the tank never empties at once. Start seed outside the tank, in rockwool cubes under a small light, and move seedlings in as older plants come out. Seedlings are ready to move once roots show through the bottom of the cube, and when to transplant seedlings covers the signs. My rhythm for six cups looks like this:
- At the start: sow two lettuce plugs plus your chosen herbs, either basil or parsley, or arugula in a cool room.
- Three weeks in: sow two more lettuce plugs, and move the first seedlings into the tank.
- By week 6: sow two more lettuce, and start picking outer leaves from the first pair.
- Every 3 weeks after that: sow two lettuce, and pull the oldest pair when it starts to stretch or turn bitter.
- Basil and parsley: replace them roughly every 8 weeks, when the stems turn woody, while arugula wants a fresh sowing every few weeks because it bolts.
That calendar is my own scheduling habit rather than a rule, and it gives two people a side salad most days with a bigger bowl at weekends. Eat more salad than that? Add a second tote rather than cramming a seventh plant into the lid. For the same idea applied to herbs in jars, see hydroponic herb succession planting, and the seed to harvest calculator turns any sowing date into a likely harvest window.
Harvesting So the Tank Keeps Giving
Loose-leaf lettuce, arugula and parsley are all cut-and-come-again crops. Pick the outer leaves at the base with clean scissors, and leave the young leaves in the center to keep growing. A plant picked this way feeds you for weeks rather than once. When the center starts to stretch upward and the leaves turn bitter, the plant is bolting, and it is time to pull it and move in a seedling.
Basil is different. Pinch or cut the tops just above a pair of leaves every week, so it grows bushy rather than tall and does not shade the lettuce beside it. How to prune hydroponic basil shows exactly where to cut. When you pull an old plant, lift the whole cup out, tease its roots free of the neighbors, and slide the new seedling in the same day, so the hole is never open to the light.
The pH, EC, light, temperature, spacing and harvest figures here are the ones the crop table on this site uses for each crop, and the crop sources page lists the research behind them. Lettuce light and temperature come from the Cornell CEA Hydroponic Lettuce Handbook, and Oklahoma State’s EC and pH guide lists crop ranges. The shared EC of 1.5 is a middle ground I use for mixed herbs and greens, and the six-cup calendar is my own scheduling habit, not a research figure.
Troubleshooting a Shared Reservoir
In a shared tank, one problem in the water reaches every plant at once. The good news is that one fix reaches them all too.
| What you see | Most likely cause | What to do |
|---|---|---|
| Yellowing new leaves across the tank | pH out of range, so nutrients are locked out | Adjust the pH to 6.0 first, then check the EC |
| Brown tips on the outer lettuce leaves | EC too high, so the lettuce edges burn | Dilute with plain water until it reads 1.2 to 1.5 |
| Brown tips on the inner lettuce leaves | Growth so fast that calcium cannot reach the center | Lower the EC to 1.0 and add a fan for airflow |
| Brown, slimy roots and a pond smell | Happens when the water is warm or the air stone has stopped | Cool the tote, check the pump, then treat the rot |
| Green film on roots or tote walls | Light getting in, so algae grows | Wrap the tote and also cover any empty holes |
| Lettuce or arugula shooting up a stalk | Bolting, especially in a warm room | Harvest it and replace it, then cool the room before the next one bolts too |
Root Rot in a Shared Tank
Healthy roots are white or cream and smell of almost nothing. Brown, slimy roots that smell of stagnant water mean rot, and in a shared tank it spreads to every plant. Act the day you notice it. Cool the water, make sure the air stone is bubbling, trim away the dead roots, and change the solution. For an active infection, add 3 ml of 3% hydrogen peroxide per liter of reservoir; hydrogen peroxide for root rot explains how to use it safely. Afterwards, run the tank at a gentler EC 1.2 to 1.5 for 4 to 7 days while the plants recover. Then read preventing root rot in small systems, and clean the tote properly before the next change with the method in cleaning a small hydroponic system.
Yellow Leaves and Drifting pH
When leaves pale across the whole tank, check the pH before you add anything. Out-of-range pH locks nutrients out even when the EC reads right, so more feed only makes it worse. If the pH wanders every day, why pH keeps drifting explains the causes, and why hydroponic plants turn yellow sorts out the other reasons.
A Word From Sarah
Write everything down on one sheet taped inside a cupboard door: the date each cup was sown and moved in, and the pH and EC every time you test. In a shared tank you are managing six plants on different clocks, and memory blurs them within a month. With a written log, you can see which pair is due out, spot a pH that creeps up every week, and know exactly when the two-week change is due. The free printable hydroponics tracker is built for exactly that.
Frequently Asked Questions
Which plants can share one hydroponic reservoir?
Lettuce, arugula, basil and parsley share a reservoir well at EC 1.5 and a pH near 6.0, since that sits inside the range of all four. Pair them by room temperature: lettuce and arugula in a cool room, lettuce with basil and parsley in a warmer one. Mint, spinach and cilantro do better in their own containers.
What EC should a mixed salad reservoir run at?
Run it at EC 1.5, a middle ground that feeds the herbs without burning the lettuce. If the tank is mostly lettuce, you can run it at lettuce’s own 1.0 to 1.4 and accept slightly slower herbs. Top off with plain pH-adjusted water, not nutrients, so the strength stays steady.
Can I use Kratky for a shared salad tote?
Yes, for a batch planted all at once. A Kratky tote is filled once and the plants drink the level down, so every plant’s roots follow the air layer together. It cannot be replanted a few cups at a time, though, because raising the level for a new seedling drowns the roots of the older plants. For a rolling salad, use an air stone.
Can mint go in the same reservoir as lettuce?
Not in a salad tank. Mint wants EC 2.0 to 2.4, which would burn lettuce, and its thick roots wrap around everything else in the water. Grow it in its own jar or bucket, where you can feed it properly and its roots cannot take over.
How often do I change the water in a shared salad tank?
Top off every day with plain water adjusted to pH 6.0, and change the whole reservoir every 2 weeks. Lift the lid with the plants still in it onto a tray, empty and rinse the tote, refill with fresh solution and put the lid back.
How many plants does it take to feed two people salad?
My rule of thumb is six cups in one tote, with two new lettuce plugs sown every 3 weeks, which gives two people a side salad most days. Picking outer leaves rather than whole heads stretches it further. If you eat more than that, add a second tote rather than crowding the first.
What grow light does a salad tote need?
A panel hung 6 to 8 inches above the leaves, on a timer for 14 hours on and 10 off. Lettuce does well at about 240 to 340 PPFD, which a countertop LED of 20 to 36 real watts per 2-foot footprint usually covers. Raise the light as the plants grow.
Why is my hydroponic lettuce turning bitter?
Bitterness usually means the plant is starting to bolt, most often because the room or the water runs warm, or simply because the plant is old. Harvest it, replace it with a seedling, and keep the room cooler. Picking outer leaves regularly keeps plants younger and sweeter for longer.
Is a shared DWC salad tank noisy?
The air pump hums quietly. Stand it on a folded towel or a foam pad, keep it out of the bedroom, and fit a check valve in the line. A Kratky tote is silent, but it suits a single batch rather than a salad you keep replanting every few weeks.
How do I keep a salad reservoir cool in summer?
Keep the water at 65 to 75°F by moving the tote away from heat and direct sun, and keep the air stone running. Never add ice to the reservoir, because the sudden cold shocks the roots. A frozen bottle stood against the outside of the tote cools it gently.
Happy growing! 🌿
Sarah, Urban Hydro Space
Sarah Whitfield is the founder of Urban Hydro Space and an indoor gardening enthusiast dedicated to helping apartment dwellers grow fresh herbs and vegetables in small spaces. She researches hydroponic systems carefully from real specifications and verified buyer feedback, and shares practical tips and honest, clearly labeled product picks to make indoor gardening accessible for beginners.
