How do the sensor modules in my Smart Hydroponics Kit work?

The Smart Hydroponics Kit is a micro:bit-powered growing system: your students program the micro:bit to control light cycles, water levels, water circulation, and pH and temperature measurements for real plants (Forward Education). The sensors and devices are what turn a plastic tank into a smart growing system.

Here is the quick tour, so you know what each part does before you hand it to a class.

The short version

Every sensor and device in the kit plugs into the breakout board — the small circuit board that acts as the hub of the project. The micro:bit slots into the breakout board, and the board passes every sensor reading through to your code. Nothing needs wiring, soldering, or a screwdriver: the modules are plug-and-play, and the cables are reversible, so students can't plug them in "backwards."

You then read those sensors (and switch on the pump and light) using the Forward Education blocks in MakeCode. If you don't see Sensors and Motors drawers in MakeCode, add the extension first — see How to add the Forward Extension in MakeCode in this knowledge base.

How the modules connect to the breakout board

The breakout board layout is shared across the Forward Education hardware ecosystem, so it works the same way as it does in the Climate Action Kit:

• The top four ports take any of the white sensor or component modules.
• The bottom three ports are for servo motors.
• The water pump has its own dedicated connection point, just to the right of the micro:bit.
• The board has a built-in rechargeable battery, so a project can run away from a desk. For a hydroponics build that runs for days at a time, keep the board plugged into power with a micro USB cable — that's the advice on the Forward Education project pages, and it saves you a dead battery mid-experiment.

More detail on the board itself lives in An in-depth look into the Climate Action Kit Sensors and Components.

According to reseller listings of the kit contents, the Smart Hydroponics Kit ships with its own breakout board (with micro:bit edge connector and rechargeable battery), and a V2 micro:bit is required and sold separately (Pakronics).

TODO: Confirm against the official Forward Education packing list whether the breakout board is included in every region's version of the kit, whether a V2 micro:bit is required, and whether the temperature sensor and probe ship with the kit or are bought separately (the reseller contents list shows pH, float and light controller modules plus the pump, but no temperature sensor).

What each module does

Float sensor (water level)

The float sensor is how your project "knows" how much water is in the tank. It sits in the reservoir and reports whether the water is above or below the float point, so students can trigger something when the level drops — for example, an alarm on the micro:bit display, or the pump refilling the reservoir. The Low-Water Alarm for Hydroponics and reservoir refill projects on learn.forwardedu.com are the fastest way to see it in action.

Classroom tip: have students physically lift and lower the float with their hand while watching the micro:bit. Seeing the reading flip is the moment the concept of a threshold lands.

pH sensor

The pH sensor measures how acidic or alkaline the nutrient water is, and reports it back to the micro:bit so students can log it, display it, or compare it over a growing cycle (Forward Education). pH is one of the most "real" pieces of data in the kit — it changes as plants feed, so it's ideal for a long-running data collection assignment.

You'll need pH up/down buffer to adjust the water, along with hydroponics nutrients. Both are consumables and are not endlessly reusable — see Where can I purchase consumables for the Smart Hydroponics Kit? in this knowledge base.

Temperature sensor and probe

The temperature module is used with a probe to measure the temperature of water, soil, or another medium (Forward Education). In a hydroponics build, students usually drop the probe into the reservoir to track water temperature alongside pH — warm water and plant health make a natural inquiry question.

Like the other modules, it has two reversible cable ports and works with any Forward Education kit, so you can borrow it for other projects.

LED grow light

The grow light is an output, not a sensor. Students can program both the on/off light cycle and the brightness, which means they can model day length for different plants and compare growth (Forward Education).

If the light won't come on, there's a dedicated article for that: My Hydroponics Light isn't working.

Water pump

The pump moves water — either circulating it around the tank to keep nutrients evenly mixed, or feeding new water in when the float sensor says the level is low. It connects to its own port on the breakout board rather than a standard sensor port.

Two habits that make pumps last:

1. Use a filter on the hose whenever you pump water out of a reservoir, to keep debris out of the pump and hose (recommended on the Water Recirculation for Hydroponics project page).
2. Store it properly at the end of a unit — see Walkthrough - How to store the water pump.

If it isn't running at all, start with The Water Pump is not working.

The growing hardware

Not everything in the box is electronic. The main hydroponics unit includes the tank (7 L capacity), cover, support posts, and plant support rods (Forward Education). Assembly is covered in Smart Hydroponics Kit Assembly Guide — follow that first, then come back to the sensors.

Test the modules before class

You don't need water in the tank to check that a module works. With the Forward Education extension added, MakeCode shows a virtual version of each sensor you plug in:

1. Turn on the breakout board.
2. Pair your micro:bit and insert it into the breakout board.
3. Plug a sensor into one of the top four ports.
4. Watch the simulator area on the left of the MakeCode workspace — the sensor appears below the micro:bit simulator and updates live as you plug modules in or out.

That gives you a 30-second pre-class check: plug each module in, see it appear, move on. More detail is in Introduction to MakeCode Simulators.

If a module isn't reading

Work through these in order — the fix is usually in the first two:

1. Check the port. Sensors go in the top four ports; the water pump goes in its own connector beside the micro:bit.
2. Check power. Make sure the breakout board is switched on and charged, or plugged into USB power for a long-running build.
3. Check the pairing. If the micro:bit won't download code or connect, see Pairing your micro:bit in MakeCode and My micro:bit is having trouble connecting. Note for planning: students will need to re-pair their micro:bit on a new computer or after a browser change.
4. Check your extension version. Older projects can be missing newer blocks — see Do I have the latest version of the Forward Education Coding blocks?
5. Swap the module into a different port, or try a known-good module, to work out whether it's the part or the port.

Still stuck? How do I contact support? has the fastest route to a human, and A piece is missing from my kit — how do I get a replacement? covers replacements.