Short answers to the questions growers ask us most. Each one links to the full guide.
About Agrowtronics and our sensors
What is Agrowtronics?
Agrowtronics is the agriculture brand of iMatrix Systems, Inc. We publish free guides on hydroponics, aquaponics, smart gardens and beekeeping, and we sell wireless sensors that give growers, greenhouses and controlled-environment farms real-time monitoring, alerts and cloud data logging through iMatrix Cloud. See About Us and all our guides.
Which sensor should I start with for a grow room or greenhouse?
Start with temperature and humidity, because they affect every stage of growth and drift the fastest. The NEO-1 and NEO-1D both log temperature, humidity, VPD, heat index and dew point around the clock; the NEO-1D adds an on-device display. See Why We Use the iMatrix Cloud System.
How do I monitor nutrient solution or reservoir temperature?
Use the NEO-1P, a submersible temperature sensor and data logger with a 39-inch cable and a 2.75-inch stainless steel probe. The NEO-1DP also has a probe and a display, but its probe is not submersible. For wet, very cold or rough locations, the NEO-IND is rated IP68 waterproof and IK09 shockproof.
How does sensor data get to the cloud?
NEO and Sentry sensors are Bluetooth Low Energy (BLE) devices. You can use the iMatrix smartphone app as a virtual gateway: it scans nearby sensors and uploads their readings, and a phone or tablet can be left running at the greenhouse. For unattended 24/7 upload, use the Micro Gateway, a Wi-Fi and Bluetooth USB gateway that also keeps sensor firmware up to date; add more than one to cover a large space. In iMatrix Cloud you get logs, graphs, reports and real-time alerts. Setup is one step: scan the sensor’s QR code with the app.
What does NIST-certified mean, and do I need it?
A NIST-certified NEO sensor is calibrated at an ISO 17025-accredited laboratory, traceable to the National Institute of Standards and Technology, verified at three or more temperature points, and shipped with a signed calibration certificate that is archived in iMatrix Cloud. You need it when your temperature records must stand up to an inspector, auditor or customer. Certified sensors can be recertified each year. See NIST Certification.
Can I get an alert if a cooler or grow room door is left open?
Yes. The Sentry-1 is a two-piece wireless door/window sensor that reports open/close status and counts entries. It has a tamper switch and a replaceable battery, and alerts go to your phone through iMatrix Cloud.
How do I order, and who processes my order?
Add products to the cart on this site. Orders are processed by iMatrix Systems through its secure checkout. Connectivity and fleet products are sold on imatrixsys.com, and their product pages link there. For anything else, use the contact page.
Getting started with hydroponics
What is hydroponics?
Hydroponics is growing plants without soil: the roots take their nutrients from nutrient-rich water instead. It is usually done indoors or in a greenhouse, grows year round, and uses around 90% less water than traditional farming. See What is Hydroponics?.
What are the main types of hydroponic systems?
The six main types are ebb and flow (flood and drain), drip, wick, deep water culture (DWC), nutrient film technique (NFT) and aeroponics. DWC and wick systems have the fewest moving parts and are the easiest for beginners. See Types of Hydroponic Systems.
What are the easiest plants to grow hydroponically?
Herbs and leafy greens. Easy herbs include basil, oregano, sage, rosemary, thyme, parsley, cilantro and watercress; they like a pH of about 5.8–6.4 and an EC of 1.2–1.8. Easy greens include lettuce, chard, spinach, kale, chives and arugula; most do best near EC 1.4 and pH 5.5–6.0, at 70–75 °F by day. See The Easiest Plants for Hydroponics.
What growing medium should I use?
Rockwool, coco coir and expanded clay pebbles are the most widely used. Perlite, vermiculite, lava rock, oasis cubes and parboiled rice husks are also common. The medium holds plants in place, retains nutrient solution and lets roots get oxygen; the right one depends on your system and how much water you want it to hold. See Hydroponic Growing Medium.
Water, nutrients and pH
What pH should a hydroponic nutrient solution be?
Most plants want a pH between 5.0 and 7.0, and each crop has its own narrower range: leafy greens about 5.5–6.0, herbs about 5.8–6.4. Outside the range, plants suffer nutrient lockout and cannot absorb what is in the water. Test several times a day when a system is new, then at least daily, and correct with pH up or pH down. See pH Imbalance.
What is EC, and what should it be?
EC (electrical conductivity) measures how concentrated the nutrients in your water are, usually in mS/cm. Most plants need 1.2–2.0 mS/cm. A low reading means add nutrients; a high reading means add fresh water. Measure it every time you add nutrients. See Hydroponic Water Changes.
How often should I change the water in a hydroponic system?
Top off daily or every few days as water is used and evaporates, and do a full change about every two to three weeks. A good rule: when the water you have topped off adds up to the reservoir’s full volume, it is time for a full change. Clean the reservoir while it is empty. See Hydroponic Water Changes.
Should I use tap water?
You can, but tap water carries minerals that build up in the reservoir alongside the ones in your nutrients. For precise feeding, reverse osmosis (RO) water gives you a clean starting point. See Water Quality in Hydroponics.
Can I make my own nutrient solution?
Yes, once you understand NPK ratios, macronutrients and micronutrients and can test pH and EC. You will need scales, measuring tools, lidded buckets and purified water. Beginners are safer starting with premixed nutrients. See Basics of DIY Nutrient Solution and Nutrients for Hydroponics.
What are chelates?
Chelates (pronounced key-LATES) are minerals bound to amino acids so plants can absorb them. They matter most for metallic micronutrients such as iron and copper: chelation buffers their toxicity and keeps them from reacting with other elements and dropping out of solution. See What are Chelates?.
What is ORP (oxidation reduction potential)?
ORP describes water’s ability to break down waste and contaminants, which depends on how much oxygen it carries. It is measured in millivolts (mV); higher ORP means more oxygen and more sterile water. See Oxidation Reduction Potential (ORP).
Climate, light and CO₂
What is VPD, and why does it matter?
Vapor pressure deficit (VPD) combines temperature and relative humidity to show how strongly the air draws water out of leaves. It controls transpiration, which is how plants move water and nutrients. VPD rises as humidity falls. Too low and plants cannot transpire and mildew risk rises; too high and they lose water faster than they can take it in. See Vapor Pressure Deficiency (VPD).
How much CO₂ do plants need?
Outdoor air is around 410 ppm. Growth is stunted below 200 ppm and most plants die below 150 ppm. Enriching to about 1,000–1,300 ppm can boost growth by around 30%; levels above 1,500–2,000 ppm become harmful. See How Much CO₂ Do Plants Need?.
How much light do hydroponic plants need?
It depends on the crop and stage. Herbs need 10–16 hours a day (about 12 suits most), leafy greens 10–14, and plants in vegetative growth 14–18. Fluorescent lights suit seedlings and clones, metal halide suits vegetative growth, and high-pressure sodium suits flowering. See Lighting for Plant Growth Stages.
How often should an ebb and flow system flood?
Each flood should last no more than 10–15 minutes. Most systems flood a few times a day; hot, dry rooms with large plants may need 10–15 floods daily. Media that hold little water, such as clay pebbles, need more frequent floods. See Timing Ebb and Flow Cycles.
Problems and maintenance
What are the most common problems in hydroponics?
Algae, pathogens and root disease, pests (aphids, fungus gnats, spider mites, thrips and whiteflies), equipment failures, power outages and pH imbalance. Most can be fixed if caught early. See 6 Common Problems in Hydroponics.
What should I do during a power outage?
Keep oxygen reaching the roots first, especially in DWC: run a battery air pump, or remove about half the solution and slowly pour it back in. Any light is better than none. In winter, keep doors closed and insulate the grow area. See Power Outage.
How often should I clean my hydroponic system?
Clean the reservoir at every full water change, and keep drains clear and dead plant material out while plants are growing. Sterilize the whole system after each harvest. Sanitize with a 50/50 vinegar and water mix or food-grade hydrogen peroxide, and avoid soap, which is hard to rinse out. See Cleaning Hydroponic Systems.
Aquaponics and beekeeping
How does aquaponics work?
Aquaponics combines fish farming with hydroponics. Fish waste fertilizes the plants, and the plants clean the water that returns to the fish. It uses the same system types as hydroponics. See How Does Aquaponics Work?.
What are the easiest fish for aquaponics?
Trout, tilapia, catfish and perch. Look for fish that are hardy, peaceful, reach plate size quickly and suit the water conditions you can hold. See Easiest Fish for Aquaponics.
What are varroa mites?
Varroa destructor is a parasitic mite that spread from the Asian honeybee to the western honeybee. It feeds on larvae and adult bees and spreads viruses, and without treatment it can destroy a colony. See Varroa Mites and DIY Varroa Mite Treatments.
