Frequently Asked Questions

Hydroponics is a subset of hydroculture, which is a method of growing plants without soil by using mineral nutrient solutions in a water solvent. Terrestrial plants may be grown with only their roots exposed to the mineral solution, or the roots may be supported by an inert medium, such as perlite or gravel.

The ideal pH range for most hydroponic crops is between 5.5 and 6.5. pH is important because it affects availability and absorption of several of the 16 atomic elements needed for plant growth. Maximum absorption of these elements is found at pH readings 5.5 to 6.5.

Typically, it only takes 1-2 ml of pH Up or Down per gallon of water to correct the pH of your nutrient solution. After adding, stir and wait 15 minutes to half hour to test the nutrient solution again. Repeat the process until you in the range of 5.5-6.5 or the desired range for what you’re growing.

Nutrients that are more basic will bond with the H- ions in water to raise the pH value. As you add fertilizers or nutrients to your garden, you may notice an increase or decrease in the pH level of the soil or water in your garden.

Do I pH the water before or after adding nutrients? You should test the pH after you add nutrients to the water (if adding nutrients). The nutrients will often change the pH of the water, and you’re concerned with making sure the pH of the water is right, as experienced by the roots.

pH levels can fluctuate daily due to photosynthesis and respiration in the water. The degree of change depends on the alkalinity of the water. Carbon dioxide is the most common cause of acidity in water ¹⁵. … This increases H2CO3, which decreases pH

Electrical conductivity or EC as it relates to hydroponics is a measure of the dissolved salt content in any given aqueous solution.

To put it more simply EC indicates how the strength of any given nutrient mix you have made up. The more nutrient you add to your mix the higher the EC will be.

EC is the primary measurement used in assessing how much nutrient to give a plant at any given point in its life cycle. As plants grow, they require more nutrition to stay strong and healthy, young plants will usually require an EC of between 0.6 and 1.6 whereas fully mature flowering plants may require an EC of between 1.6 – 2.4

Seedling requirements: 0.4 – 0.6

Growth/Vegetative requirements: 0.6 – 1.6 EC

Bloom/Flowering requirements: 1.6 – 2.4 EC

There are several tools available to test the Total Dissolved Solids present in a nutrient solution. Where it gets confusing is which units to display your values in. The most common are Electro Conductivity (EC) and Parts Per Million (PPM). EC is the best way to display the TDS of a nutrient solution because it is a universal unit. Unlike PPM which is EC x 0.5 or EC x 0.7. Since there are two different conversions of EC to PPM, PPM becomes an unreliable way to describe nutrient concentrations because you never know whether someone is using the same scale as you are. To break it down:

* Electro Conductivity is displayed in EC or EC x 1000.

* Parts Per Million is either EC x 0.5 or EC x 0.7

* Therefore 2.0 EC or 2000 EC = 1000 PPM or 1400 PPM depending on which conversion factor is used.

2000 EC x 0.5 = 1000 PPM or 2000 EC x 0.7 = 1400 PPM

Seeing as how there are two different PPM values for the same EC value depending on conversion factor used, EC is a much better way to describe nutrient concentrations.

A General Guide for media such as Perlite and Expanded Clay Balls.

Vegetative: 840 PPM – 1540 PPM | 1.2-2.2 EC

Flowering: 1260 PPM – 1680 PPM | 1.8- 2.4 EC

A General Guide for media such as Coconut Fibre

Vegetative: 840 PPM – 1400 PPM | 1.2-2.0 EC

Flowering: 1260 PPM – 1540 PPM | 1.8- 2.2 EC

What pH should I maintain?

6.0 – 6.6 Re circulation

5.5 – 5.8 Run to Waste

The choice of light used in your grow room will arguably be your most important decision when setting your space. There are several lighting options to consider when building a hydroponics set up. All options have their pros and cons, and these should be considered carefully before making your decision.

The most common choices are High Intensity Discharge (HID), Light Emitting Diodes (LED) and Florescent lighting.

HID lights are the most common grow light used they have been the industry standard for decades now and as a result the price of these lights has become very affordable. They have shown to give gardeners consistent results over the decades when used correctly.

The down side to this option is the colour spectrum for HID lights are quite limited thus you will need to use two separate lamps (globes) for different stages of growth.

During the vegetive stage it is best to use a Metal Halide HID Lamp and then for the bloom stage it is advised to use High Pressure Sodium lamp these lamps should be swapped out for new lamps every 6-12 months.

Often another down side to this option is HID lights run very hot therefor it can be difficult to control temperatures in your growing space. If temperatures exceed 29 degrees in a grow room, it can severely affect the quality of the finished product.

A promising new evolution in the HID market has been Light Emitting Ceramic (LEC) fixtures also known as Ceramic Metal Halide (CMH). These new HID lights offer the plants a full light spectrum and run more efficiently than older HID options.

The down sides to these lights are they still produce a lot of heat and they cannot be powered by traditional HID ballasts as they require specific low frequency ballasts to operate.

LED grow light fixtures are becoming more and more common and can offer growers very impressive results due to their wide range in colour spectrums and incredibly efficient energy use.

Unfortunately, due to a large amount of cheap, sub-par LED grow light models flooding the market over the last 5 or so years the true potential of LEDs hasn’t been fully realized by gardeners.

As LED technology improves and the market becomes more savvy there are more companies offering high quality and extremely powerful LED fixtures for all type’s horticulture.

The general rule of thumb for vegetating plants is 18 hours of light and 6 hours of darkness, once flowering has begun or the plant is of suitable size to flower you will need to change your photoperiod to 12 hours on and 12 hours off, keeping in mind that once your plants start flowering the darkness cannot be interrupted, if light enters the space when flowering, you could reset the plant to vegetate or even worse, they can mutate which will massively impact the end result. It is not recommended that plants receive 24 hours of continuous light at any time during the life cycle. Many growers will leave their lights off for the final 36-48 hours of their grow to great results.

Reservoirs should be emptied, and the nutrient solution replaced at least every 5-7 days. People often use their EC/TDS meters to measure nutrient levels and top up their nutrient solution when levels get low. EC/TDS meters only measure overall salt levels, not the levels of specific nutrients. This means nutrients not completely used by your plants will begin to build up to potentially toxic levels. Emptying your reservoir and replacing your nutrient solution with a quality fertilizer is the only way to ensure nutrient levels are consistently in the ideal range for plant growth.

Organic fertilizers are derived from natural, organic compounds such as compost, manure and worm castings. Inorganic fertilizers are created using inorganic compounds made through chemical processes. As far as your plants are concerned, organic and inorganic nutrients are relatively the same
They can have virtually the same nutrient levels, and at a molecular level these nutrients are the same. Many organic fertilizers need symbiotic fungi and bacteria to break them down before the fertilizer is readily available, while others are pre-digested and instantly available to your plants. Some people find that organic nutrients allow more sludge to build up in their reservoir. Just remember, it is not safe to use hydrogen peroxide with organic nutrients, as it will kill off all the beneficial fungi and bacteria.

There are many supplements that will increase flower size. Most common are bloom boosters that are concentrated in powder form and are high in phosphorus. Bat guano supplements also increase flower growth and I also really like foliar spraying with folic acid, often labelled gold. This will increase the number of flower sites and act as a chelating agent, helping your plants absorb macronutrients more efficiently.

The ideal grow room temperature varies depending on what types of plants you are growing. Tropical plants like orchids and plants like succulents do well at 27 C and up. Plants such as kale and broccoli do best at cooler temperatures in the, 15-20°C range. Plants like tomatoes do well in the 20-24 °C range. Temperature is important for more reasons than plant growth. When the temperature surpasses 27°C, insects can multiply much faster than at cooler temperatures. Soil and soilless mediums will dry out more quickly, increasing water consumption, and soil will become toxic with concentrated nutrients. The higher temperatures also reduce the amount of oxygen available in the nutrient solution.

That scummy, sludgy build-up in your reservoir could be algae, bacteria or fungi. These organisms rob your reservoir of oxygen and nutrients, leaving nothing for your plants. They clog pumps and drippers, causing nightmares in the grow room. Regardless of what it is, it is usually caused by light entering your reservoir combined with higher reservoir temperatures.

Keeping your reservoir cooler, either with a reservoir chiller or by keeping your room cool, will make a huge difference. Covering your reservoir with either a lid or black and white plastic, white side facing up, will keep the light out.

You can also add hydrogen peroxide to your nutrient solution at each reservoir change to help eliminate the sludge. Cleaning your reservoir between crops is important to keep the sludge from returning.

HID light bulbs come in a variety of spectrums and strengths to meet the needs of indoor gardeners. The lumens and PAR (photosynthetically active radiation) levels drop quickly. You can check this for yourself by measuring your yields with new bulbs versus bulbs that are 8-12 months old.
The newer bulbs in the same environment should offer noticeably larger yields over the old ones. After 8-12 months of continuous use, the bulb should be replaced.

The main purpose of ventilation in a grow room is to expel hot and humid air and to replenish CO2. Finding the perfect balance between optimum temperature, humidity and CO2 can be tricky and thus investing in the right gear from the start is important. A good quality variable speed extractor fan will serve you well. As a general rule, you want an extractor fan that can complete a total exchange of vapour within the grow room every 1 – 3 minutes.

There are numerous benefits to gardening using hydroponics. Hydroponic systems use less water than traditional gardens. They are also cleaner, since you are not bringing soil into your home. Hydroponic systems are less likely to host destructive insects, and you can grow indoors year-round.

The biggest advantage hydroponics has over traditional gardening is significantly larger yields in less time. That means more crop rotations per year, and more money in the pockets of commercial growers. This is because

Powdery mildew is a fungal infection on plant leaves caused by high humidity and poor ventilation. Preventing powdery mildew is as simple as keeping your grow room’s humidity level below 65% and providing ample air circulation. Air circulation can be improved by venting your room more often. Including ceiling fans or oscillating fans in your room can make a big difference.

Spraying your leaves with the lights out can invite powdery mildew onto your plants. There are a couple ways to treat powdery mildew. Spraying or dusting your plants with sulphur will kill the powdery mildew.

Neem oil and pine tree oil foliar sprays also work at removing and preventing powdery mildew. For large-scale removal, the best choice is a sulphur burner. This will vaporize sulphur pellets, filling your room with a sulphur mist, killing the powdery mildew.

There are numerous reasons why your leaves may be yellowing. The most common problem is a yellowing of the older, lower leaves on the plant. This is caused by a nitrogen deficiency. There is not enough nitrogen available for your fast-growing plants, causing them to take nitrogen from the older leaves and send it to the new shoots. This can usually be corrected by adding some more nitrogen to your feeding schedule.

Adding worm castings and pine tree oil are two safe ways to get more nitrogen to your plants. If the yellowing is occurring in the newer leaves, it is likely caused by a micronutrient lockout. The usual cause of this is a toxicity of either phosphorus or potassium, or high or low pH levels.

Flush your growing medium with pH-balanced water and begin watering with a quality nutrient solution. Heat from your lamps can also cause some of the leaves closest to the bulb to turn yellow or even dark brown.

Simply position your bulbs further from the canopy. Finally, overwatering can turn leaves yellow. The lack of oxygen available in the root zone will starve the plant and affect chlorophyll production.

This is the most common customer question I get asked. Spider mites are the bane of every indoor gardener’s existence. These miniscule insects feed on your plant’s juices and can decimate crops. Spider mites are hard to detect, mainly because they are so small, and once you realize you have them, it is often too late.

You may notice stunted growth initially, then on closer inspection, there may be some webbing in your plants. The damage will show up as dried-out silvery spots on the younger, more vulnerable leaves, which will die and drop. Affected plants can be treated in a variety of ways.

Many people resort to insecticides. You can also spray plants with neem oil or homemade insecticidal soap (water, dish soap, garlic and cayenne pepper). These two remedies will coat the body of the spider mite, preventing moulting and reproduction. Make sure you spray the undersides of the leaves, as this is where many adults and eggs are hiding. Another solution is predatory insects.

Predator mites and ladybugs make great natural spider mite controls, but do not use beneficial insects along with any pesticides or sprays because they will kill the good bugs as well as the bad ones. The best way to deal with spider mites is to prevent them from getting into your indoor garden in the first place. Always be clean and wash up before entering your grow room.

Avoid touching your plants to prevent bug transfer and keep pets away from your plants. Keeping your grow room temperature below 27°C will also help keep spider mite populations down, as the higher the room temperature, the faster the spider mites can reproduce.