FAQ'S

 

 



1. NUTRIENT & WATER TESTING:

WHAT IS PH?

pH, or Potential of Hydrogen, is a measure of the acidity or alkalinity of a solution. Aqueous solutions at 25°C with a pH less than seven are considered acidic, while those with a pH greater than seven are considered basic (alkaline).


A pH meter can be very useful in a variety of situations, from measuring drinking water to pools water, or for many industrial or commercial applications.


HM Digital’s PH-200 is an extremely reliable pH meter that is very easy to use, easy to calibrate and offers excellent repeatability. Compared to chemicals or paper strips, where questionable color comparisons are required, with the PH-200, it’s a simple matter of turning the meter, dipping it in the liquid and reading the pH value on the LCD display.

 pH is one of the most important factors in nutrient management and can be the difference between a successful healthy crop and a total failure. The below chart shows you which elements are absorbed by the plant at different pH levels, with maximum nutrient absorption occurring between 5.5 – 6.5 across all elements.

 


2. WHAT IS TDS(EC)?

Total Dissolved Solids (TDS) or Electric Conductivity (EC) are the total amount of mobile charged ions, including minerals, salts or metals dissolved in a given volume of water, expressed in units of mg per unit volume of water (mg/L), also referred to as parts per million (ppm). TDS/EC is directly related to the purity of water and the quality of water purification systems and affects everything that consumes, lives in, or uses water, whether organic or inorganic, whether for better or for worse.

 What Are TDS ?

"Dissolved solids" refer to any minerals, salts, metals, cations or anions dissolved in water. This includes anything present in water other than the pure water (H20) molecule and suspended solids. (Suspended solids are any particles/substances that are neither dissolved nor settled in the water, such as wood pulp.)

In general, the total dissolved solids concentration is the sum of the cations (positively charged) and anions (negatively charged) ions in the water.

Parts per Million (ppm) is the weight-to-weight ratio of any ion to water.

A TDS meter is based on the electrical conductivity (EC) of water. Pure H20 has virtually zero conductivity. Conductivity is usually about 100 times the total cations or anions expressed as equivalents. TDS is calculated by converting the EC by a factor of 0.5 to 1.0 times the EC, depending upon the levels. Typically, the higher the level of EC, the higher the conversion factor to determine the TDS.

What EC (PPM) or CF should I maintain?

This changes with the growth phase and time of year, it is also different for each nutrient brand. The following recommendations are for RAPID Range Nutrients and most of the quality nutrients 

GROWTH PHASE: SUMMER WINTER

VEGETATIVE: 1260PPM 1400PPM

1.8 EC 2.0 EC

25 CF 24 CF

 FLOWERING: 1260PPM 1400PPM

1.8 EC 2.0 EC

24CF 24CF

What pH should I maintain?

The pH should be kept between 5.8-6.3 throughout cycle

 Does the nutrient solution need to be heated?

It is best to maintain nutrient solution between 18-21 degrees in cooler weather to maintain optimum growth. If the room temperature falls below 17 degrees during the dark period, then you will require heating. There are a number of water heaters available from our store. The pH can fluctuate if the water temperatures change.

 



3. COMMON QUESTIONS WHEN GROWING 

How long should I run my lights?

Vegetative phase = 18 hours per day. Flowering phase = 12 hours per day.

What causes plants to die?

There can be a number of reasons for this. Firstly, eliminate the obvious things like lack of water, high temperature or a broken stem. Root diseases are the most common cause of sudden death of plants and can cause many problems from loss of yield to complete collapse. Pythium is the most common disease,

Remedy: Applying DeFuse to your nutrients solution will eliminate any root diseases and many other fungal & bacterial problems.

 

What causes the tips of the plants to burn?

This can be caused by too much fertiliser (too high EC), too much salt in the water, not enough water, or lights too close. Certain nutrient deficiencies can also cause leaf tip burn. Use a good nutrient and if in doubt change nutrient solution.

 

What cause leaves to turn yellow?

This can be caused by a number of factors:

  • Low oxygen levels due to lack of aeration or too much water.
  • The onset of root disease.
  • The pH is too high.
  • The solution is too hot.
  • Too much salt in the water.

All of these stop the plant from taking up nutrients in the correct quantities and balance.

Remedy: Use Go Green or Cal-Max to rectify the deficiency, just add to your nutrient solution.

 

Why do plants stretch?

Plants stretch when the light is insufficient or humidity is too high. Lack of ventilation is normally the cause of high humidity, as well as too many plants in a small area. Plants stretch when the light is too far away from the plants or there may be too many plants competing with each other for the light.

 

What humidity should I maintain?

Humidity is best maintained at around 50% in the centre of the plant canopy. Between 40%-60% is OK. Too high humidity runs the risk of disease and stretching.

 

What temperature should the growing room be?

Room temperature needs to be maintained at around 28 degrees in the vegetative phase and a couple of degrees lower in the flowering stage. It is better also to have dark period temperature lower than the light period temperature. 15-18 degrees during the dark period is ok in flowering stage.

 

How much ventilation is necessary?

Ventilation needs to be enough to maintain a temperature of about 28 degrees and a humidity of about 50% in the centre of the plant canopy. Generally it’s better to have too much than too little ventilation. As a rule of thumb, during summer give about 120ltrs per second of air going in and the same amount being vented per square metre of floor area. Try to maintain the temperature inside no higher than outside. In winter, vent according to temperature and humidity, you will usually need less ventilation.

 

Should I use EC & pH meters?

Trying to run a hydroponics system without meters is very difficult and it would be hard to achieve optimum results.

 

What size reservoir should I run?

For ease of control use a minimum of 45 ltrs per/m2 of growing area, less than this requires frequent adjustments.

 

Is it necessary to prune leaf plants?

There is no real need to prune leaf plants provided they aren't being grown too large. Large plants may need some of the larger lower leaves removed, especially if they go pale green or yellow.

Is it necessary to aerate the nutrient solution?

Aerating the nutrient solution is a good idea. It guards against stagnant water and improves plant health.

How long should it take for clones to strike roots?

The time taken to strike roots on clones varies according to the time of the year and the health of the clones. About 5-12 days is usual. Using Rhitzotonic or Roots Exelurator for a powerful root stimulant and keeping the health of the plant in optimum form.

What is the best water to use?

The best water will have low salts or contaminants. Rainwater is probably best though normal tap water is usually satisfactory and convenient as long as it is under 1500ppm. The lower the ppm the better the results.

 



4. HOW TO SET UP A HYDROPONIC GROW ROOM FOR BEGINNERS

An indoor hydroponic grow room can be set up just about anywhere, from a spare room to a garage or shed. There are just a few things that you need to take into consideration when picking out the perfect place for a Hydroponic Grow Room.

To get an idea of just what your plants will require, picture a sunny spot of an outside garden on a warm summer's day. Just about any plant will grow well in these conditions. And this is the same exact conditions that we need to recreate in an indoor hydroponic grow room. There are three major categories that we need to focus on in creating a grow room: temperature, humidity, light.

Hydroponic Grow Room Temperatures

Temperature is one of the most important design considerations you must consider when setting up a Hydroponic Grow Room. Most plants do well in a temperature range of 20-28°C, with the mid twenties being optimal.

It is not that difficult to achieve this temperature range in your grow room, especially when the lights are on. In your warmer climates if your temps become too high, inlet & extractor fans pumping the hot air out of the room will control temps well.

You can set up a thermostat to your fan to automate things. When the lights are off you need to make sure that your temperatures do not become too low. Most of all you will want to avoid huge temperature fluctuations between the day and night cycles because this will make your plants poorly formed.

 

Hydroponic Grow Room Humidity

Another aspect of controlling the conditions in your Hydroponic Grow Room is maintaining a healthy humidity level. Excessive humidity for long periods will create undesirable conditions that are perfect for grey mould. Grey mould once started will quickly spread and affect your entire crop.

Using a device called a hygrometer mounted on the wall inside your hydroponic grow room will let you know at a quick glance what your humidity levels are. Humidity levels of just above 50%, is perfect and should not go above this. It is important to keep nutrient reservoirs covered at all times so that they do not contribute to higher humidity levels.

Humidity levels can be easily controlled as with temperature by using inlet & extractor fans to rid the room of heat or humidity. As a general rule it is good to keep your grow rooms dry. This will prevent any mould problems.

Hydroponic Grow Room Lights

If you had to choose one thing that was the most important in maintaining a hydroponic grow room it would be Lighting. Now this will not matter much if you are in a greenhouse located outside, but if you are in a cellar or in a structure with a normal roof you will have to provide the light yourself and recreate light that is similar to the suns rays.

The good news is that with modern day horticulture, technology has created sun light that operates in an efficient and cost effective manner. In fact if you are choosing to set up a hydroponic grow room indoors it is best that you use only artificial lighting and do not bring light in through windows or skylights. Artificial lighting is easily controlled and provides the growers the ability to set the lights on timers to turn them on and off as needed.

By using artificial lighting the grower can simulate the long days of summer for high growth levels, and slowly start reducing the light to simulate fall and induce the plants to start flowering. A hydroponic grow room designed well will produce great results in almost any type of plant that you decide to grow.

 


5. HYDROPONIC SYSTEMS

Hydroponics is the method of growing plants without soil. It is a more efficient way to provide water and nutrients to your plants. Soil provides nutrients that must be broken down into a useable form and serves to anchor a plant's roots.

Hydroponics uses a wet growing medium and a specially prepared nutrient solution which is readily available to the plant.

In soil, plants must grow a large root system to find food and water. In Hydroponics, food and water go directly to the roots. This enables the plant to spend more energy growing above the surface, producing more vegetation, larger fruit, flowers and vegetables.

Plants grown in hydroponics systems grow up to two times faster and with larger yields than with conventional soil gardening methods due to the high oxygen levels to the root system, optimum pH levels for increased nutrient and water uptake and optimum balanced and high grade nutrient solutions.

Because Hydroponics root systems are compact in size, plants may be grown closer together. Add to this the fact that there is no weeding, fewer pests and lower water requirements. It is easy to see why home hobbyists, schools and research institutes, as well as commercial growers around the world use Hydroponics.

Hydroponic gardens can be used anywhere as long as sufficient light is provided with ample ventilation. Outdoors, much of the work associated with conventional gardening can be eliminated. Add the proper growing lights and you need not be limited to seasons.

It's quite easy to maintain a Hydroponic system:

  • Simply add water to the reservoir tank.
  • Add the proper ratio of nutrients.
  • Use a timer with the pump and water in cycles depending on the Hydroponics Method and crop type.
  • Keep the pH at 6.0 to 6.8.
  • Top up the Reservoir with water when it gets too low.
  • Change out the solution every 1—3 weeks depending on water consumption.

Our Hydroponics Systems range from shelf size, room size, or big enough to fill an entire greenhouse. Every system we offer can be purchased as a complete ready to grow kit, or in basic, bare bones kits.

With little experience you can enjoy fresh herbs, vegetables and flowers year-round.

 

There are 2 basic kinds of hydroponics systems

Ebb & Flow (Flood & Drain) System

The Ebb and Flow system works by temporarily flooding the grow tray with nutrient solution and then draining the solution back into the reservoir. This action is normally done with a submerged pump that is connected to a timer.

When the timer turns the pump on the nutrient solution is pumped into the grow tray. When the timer shuts the pump off the nutrient solution flows back into the reservoir. The timer is set to come on several times a day, depending on the size and type of plants, temperature and humidity and the type of growing medium used.

The Ebb and Flow is a versatile system that can be used with a variety of growing mediums. The entire grow tray can be filled with Clay Pebbles, gravel or granular Rockwool. Many people like to use individual pots filled with growing medium, this makes it easier to move plants around or even move them in or out of the system. Plus the growing medium retains moisture making plant growth more efficient.

Drip Systems

Drip systems are probably the most widely used type of hydroponics system in the world. Operation is simple, a timer controls a submersed pump. The timer turns the pump on and nutrient solution is dripped onto the base of each plant by a small drip line. In a Recovery Drip System the excess nutrient solution that runs off is collected back in the reservoir for re-use. The Non-Recovery System does not collect the run off.

A recovery system (recirculating) uses nutrient solution a bit more efficiently, as excess solution is reused, this also allows for the use of a more inexpensive timer because a recovery system doesn't require precise control of the watering cycles. The non-recovery system needs to have a more precise timer so that watering cycles can be adjusted to insure that the plants get enough nutrient solution and the runoff is kept to a minimum. A recovery system can have large shifts in the pH and nutrient strength levels that require periodic checking and adjusting.

The non-recovery system (run off) requires less maintenance due to the fact that the excess nutrient solution isn't recycled back into the reservoir, so the nutrient strength and pH of the reservoir will not vary. This means that you can fill the reservoir with pH adjusted nutrient solution and then forget it until you need to mix more.


6. HYDROPONIC GROW LIGHTS

What is HID lighting?

High Intensity Discharge (HID) is one of the most efficient types of grow lighting that can be purchased. There are two types of HID, Metal Halide (MH) and High Pressure Sodium (HPS).

Is it safe to run these type of grow lights in my home?

These indoor grow lights are very safe. HID lighting systems are used in retail and groceries stores, gas stations, street lights and even in your back yard as a security light. Systems that are UL tested help assure safe lighting fixtures.

Why should I use HID grow lights for my indoor plants?

HID growing lights are the most intense source of grow light available. It is also more efficient and the lamps last up to six times longer than other lamps.

When should I use fluorescent lamps?

Fluorescent indoor grow lights work best for seedlings.

Which type of light should I use?

Metal Halide (MH) grow lights work better for vegetative growth and should be used as the primary light source for any plants. High Pressure Sodium (HPS) grow lights work best for fruiting and flowering plants. It works even better if you have another light source such as a window, greenhouse or sunroof.

 

Lumens are for People, PAR is for Plants

PAR=Photosynthetically Active Radiation

How is Light Measured?
The "color" of light sources comes from a complicated relationship derived from a number of different measurements, including correlated color temperature (CCT) or Kelvin temperature (K), color rendering index (CRI), and spectral distribution (PAR Watts). However, color is most accurately described by a combination of Kelvin temperature and CRI. 

Color Rendering Index - CRI 

CRI is a numeric indication of a lamp's ability to render individual colors accurately. The CRI value comes from a comparison of the lamp's spectral distribution to the standard (e.g. a black body or the daytime sky) at the same color temperature. The higher the CRI the more natural and vibrant the colors will look. A bulb with a CRI of 85 or higher is excellent being that the sun has a CRI of 100. Eye Hortilux makes 90 -92 CRI bulbs that are used in aquarium, horticulture and other applications such as the 400W Eye Hortilux Blue 90CRI and 1000W Eye Hortilux Blue 92CRI. Standard Metal Halide bulbs have a CRI of about 70, so only 70% of colors will be rendered correctly. HPS bulbs have a CRI of 22. 

What is the Color Temperature or "K" - Kelvin Rating?

The K rating is a generalized form of addressing the color output of a Light Bulb. Color Temperature is not how hot the lamp is. Color temperature is the relative whiteness of a piece of tungsten steel heated to that temperature in degrees Kelvin. HPS has a warm (red) color temperature of around 2700K as compared to MH at 4200K, which has a cool (blue) color temperature. The higher the kelvin temperature gets, the bluer. 10k lamps seem to be a nice crisp white, while higher kelvin can go from a blue/white to very blue and lower kelvin seem more like that of sunlight (6500k). Metal Halide bulbs go up to 20,000K (commonly used in aquariums) providing the bluest light. 

What is Spectral Energy Distribution & PAR Watts?

The total visible spectrum is perceived by us humans as white light, but the "white light" is actually separated into a spectrum of colors from violet to blue, to green, yellow, orange and red made up of different wavelengths. Plants use the blue to red part of the spectrum as their energy source for photosynthesis. The different combinations and the relative intensity of various wavelengths of light determines the CRI of a light source. 
Only part of solar radiation is used by plants for photosynthesis. This active radiation Photo synthetically Active Radiation (PAR) contains the wavelengths between 400 and 700 nanometers and falls just within the visible spectrum (380 - 770nm). The light in this region is called PAR watts when measuring the total amount of energy emitted per second. PAR watts directly indicates how much light energy is available for plants to use in photosynthesis.


What are Lumens and how do you Measure Them?

“Lumen” is the unit of total light output from a light source. The problem is that the various units - candela, candlepower, lumens, lux, foot-candle - get very confusing. 

Lumens is a measure of light flux, so is independent of the area. It is essentially the amount of light available. So think of a bright light. It has a fixed amount of lumens, regardless of how near or far you are from it. 

Lux is the light level at a surface. If you think of a light bulb, the lux will vary with the distance from the light source because the light spreads out. 

1 lux = 1 lumen per sq meter. 

Traditionally, lumens have been the benchmark of a lamps ability to grow plants; meaning the brighter the lamp the better the plant. However, studies have shown that a broader color spectrum lamp will perform much better than a lamp with high lumen output, especially when it comes to plant growth.

Light meters: Most light meters read out in lux, which is a measure of the brightness at a surface. You will measure more luxes when you are closer to the bulb, than when farther away. 

Suppose you are measuring a compact flourescent light bulb (CFL), which is roughly cylindrical in shape. You use your light meter and read 1000 foot-candles at about 1/2" from the lightbulb. How do you compute the lumens of the lightbulb? 

(1) Convert the foot-candles to lux: 

1000 foot-candles = 10764 lux 

SPECTRAL PAR 

Lighting Spectrum and Photosynthesis

The most common mistake people make with plants is to not understand photosynthesis and the visible spectrum of lighting that affects plant growth. Most people choose lighting solely based on the Kelvin temperature of a bulb. This tells you very little about what type of light within the spectrum is being emitted and at what strength. Visible light is on a scale in nanometers (radiated wavelength) from 400nm (violet) to 700nm (red). 

Simple matter of photosynthesis: plants can only utilize light that is absorbed. Bright light is essential yet only a portion of this white light is used for photosynthesis. The blue and red zones of the visible spectrum are the most beneficial to plants. Green plants appear green because it is reflected light. How "bright" a light appears has more to do with how much light is output in a given area visible to the human eye, with "brightness" being at a maximum in the green spectrum (middle of visible spectrum, or around 550nm).


7. MYCORRHIZAL FUNGI IN HYDROPONICS

Q. I already use Trichoderma. Are mycorrhizal fungi any different?

Both are beneficial fungi found naturally in soil. Trichoderma are more for cycling nutrients in the soil and providing protection against soil pests (but you will seldom find it labeled as a pest control) while mycorrhizal fungi help more with nutrient and water uptake and increased root growth. Both combined will promote a very healthy root system overall.The two work together well. Trichoderma help make nutrients soluble. Mycorrhizal fungi can actually take the nutrients up and translocate them into the plant.

Q. How do I successfully introduce and propagate mycorrhizal fungi in my hydroponic garden?

Mycorrhizal fungi can be mixed directly with soil-less media or added to the nutrient solution directly just like any regular powder supplement. There is a myth that you cannot use mycorrhizal fungi with synthetic / mineral-based nutrients, but this is not true. Mycorrhizal fungi can be used with soil, hydroponics and cuttings. The key benefits in hydroponics are extended root systems (which naturally lead to an increase in yield), not to mention protection against root zone pests and diseases. Imagine miles of mycorrhizae hyphae exploring the nutrient resources. Mycorrhizal fungi cause roots to branch and form more fine feeder roots that can go after nutrients and minerals.

Q. Should I feed mycorrhizae carbs? (e.g. molasses?)

Molasses and other carbs are good for feeding bacteria and other types of fungi. But you don't need to feed the mycorrhizae. That's missing the point. The plant feeds them! It's the exudates from the plant roots that cause the mycorrhizal propagules to germinate. (There are synthetic compounds that cause the mycorrhizae to germinate but they are unnatural, expensive and not commonly available.) You are better off adding products which contain humic acids (organic growers can use high quality organic inputs such as North Atlantic sea kelp) to promote more root exudates (food for the mycorrhizae).

Q. What hydroponic growth media do mycorrhizae prefer?

Mycorrhizal fungi can create mycelial networks in soil, coco coir, rockwool and many other inert growth media. They can even survive in a totally aqueous environment, as long as it is properly aerated, but they will not replicate. Mycorrhizae will grow and increase in biomass only once they are attached to a plant root.

Q. What about mycorrhizal fungi and high phosphorus levels?

Mycorrhizae fungi spores 'sleep' while levels of phosphorus are high (above 70ppm). They only awaken when levels drop lower than this. This is another reason to establish your mycorrhizae as early on in the plant's development cycle as possible.

Q. What conditions do mycorrhizal fungi prefer?

Temperature: around 68-73°F is ideal but mycorrhizae can also help your plants tolerate occasional temp extremes.

Moisture: mycorrhizal fungi like to have a good air/water mix to thrive. Too moist or too dry is not ideal. Once again, they will help the plant tolerate any extremes that occur.

pH: it depends on the mycorrhizae species but generally they thrive in 5.5-7.5. Some can tolerate acidic conditions better than others while some like alkaline better than others. Look for products that are made from a blend of different species in order to create a healthy mycorrhizae population that will thrive in varying pH conditions.

Q. What conditions should be avoided?

Very high temperatures. (135- 140°F will definitely start killing them off but then, at those temperatures, the happiness of your fungi is the least of your problems!) The less chlorine your water contains, the better for both fungi and plants too. However, typical levels of chlorine from municipal supplies should not cause a problem.

Q. When should I start using mycorrhizal fungi?

As soon as possible! It takes less mycorrhizae to colonize a juvenile plant than a larger one. Commercial growers have negated the cost of mycorrhizal fungi with their increased seed germination rates. It takes a couple of weeks to form on the roots after the first inoculation so get the process started right at the seedling / cutting stage. The trick is to introduce the mycorrhizal fungi spores as early as possible to give them time to establish themselves. This is particularly important if you are growing short-cycle plants.

Q. Do mycorrhizal fungi need to be reintroduced on a regular basis? Do I need to add it more frequently than once with every nutrient change?

Best performance is achieved with numerous applications throughout the growth cycle. You can't really overdo mycorrhizae. If there are more roots producing more exudates it will probably help to add more mycorrhizae. But don't bother any later than 2-3 weeks before harvest. It's a waste of time. Your mycelial network should already be established. It won't do any harm to keep using it (and often the instructions on the mycorrhizae product will encourage you to!), but you're just wasting your money! Adding it with every nutrient change won't do any harm either. It's just a question of minimizing waste. A good tip is to mix the fungi in a one gallon jug to get it nicely diluted, then pour it into your nutrient solution. Otherwise the powder can sit at the bottom of the res. The white powder you sometimes see at the bottom of your res is just the carrying agent of the spores, not the spores themselves.

Q. What mycorrhizae products can I find in my local grow store?

You'd best ask down at your store! You'll most likely find a few different brands. The products usually come as a jar of white powder - this is a 'carrying agent' for the spores. If you want to compare products, look for the number of mycorrhizal species per pound and the diversity of species. Oh, and the price!

Q. Ok, but how do I actually use mycorrhizal fungi to benefit my plants?

Mycorrhizal application is easy and requires no special equipment. The goal is to create physical contact between the mycorrhizal inoculant and the plant root. Mycorrhizal inoculant can be sprinkled onto roots during transplanting, worked into seed beds, blended into loose growth media, "watered in" via existing irrigation systems, added directly to the nutrient solution, applied as a root dip gel or even probed into the root zone of existing plants. Most hydroponic growers simply add the fungi by diluting the powder holding the spores into some water and adding this to their nutrient solution. It's very easy.

Q. Do mycorrhizal fungi actually guard the roots against other nasties? If so, which nasties exactly?

Yes. Nasties include: rhizoctonia, fusarium, pythium and phytophthora. They can also mitigate the detrimental effects of high salt conditions.

Q. How exactly do mycorrhizal fungi guard the roots? Do they simply "crowd out" the root zone or is it more complex?

Endo mycorrhizal fungi thicken the cell walls around the root cortex making it harder for pathogens to penetrate. They also compete with pathogens for some of the same food sources. Mycorrhizal fungi help with antibiotic production, armoring of roots with chitin, and control of excess nutrients.

Q. What's the difference between "endo" and "ecto" mycorrhizal fungi?

Endo = has an exchange mechanism inside the root (and hyphae extends outside of the root). Ecto= lives only outside the root. The endo mycorrhizae form with mostly green, leafy plants and most commercially produced plants. Ecto mycorrhizae form with mainly conifers and oaks: more woody plants. Endos are for everything else. In hydroponics, ectos don't even matter. Fruits, veg, flowers ... stuff we love to grow ... they love endo.

Q. Are there any differences in how the hydroponic grower should use mycorrhizal fungi compared with the organic grower?

Both types of grower need to get the inoculum near roots. Same product, same application rates. Same number of spores per square foot. Both types of growers can reduce their nitrogen and phosphorus inputs.

Q. Do mycorrhizal fungi help with nutrient extraction in a hydroponic environment or are they more relevant in soil / organics where nutrients need to be broken down first in order to become available?

Mycorrhizal fungi are just as effective in hydroponic applications as they are in organics / soil. A main function of mycorrhizal fungi is phosphorus uptake. It's important to have a good colonization and a good mycorrhizal fungi "web" already established before you go into flowering.