Marijuana Growing in Aquaponics – Part 3

Marijuana Growing in Aquaponics – Part 3

By Colle and Phyllis Davis 

Read our Three-Part Series on Marijuana Growing in Aquaponics

Marijuana Growing in Aquaponics – Part 1

Marijuana Growing in Aquaponics – Part 2

Marijuana Growing in Aquaponics – Part 3


We devote our final article in this three-part series focused on growing medicinal herbs in aquaponics for maximizing the growth of marijuana. This article excludes all other aquaponics’ crops and focuses solely on giving the herbs the most significant advantages they require to produce the best plant, bud, and quality.


Marijuana growing in both hydroponics and aquaponics has been a mainstay in both industries for years.

We have offered a state-by-state list of US states that allow and those
that do not allow growing marijuana in
Part 1 of this series.

  • Growing marijuana with hydroponics has been popular for decades. Growers simply put a few seeds in a half-dozen pots filled with soil and placed the pots in the bottom of their closet with artificial lighting and enjoyed the results.
  • In addition, growing marijuana in aquaponics has been a popular way to raise the plants in grow tables installed in private garages and basements with the addition of artificial lighting.

Mustard Greens growing in a Portable Farms Aquaponics System Grow Table.

Maximizing your production requires more time, effort, and money in the planning, building, and growing phases of your operation.

    • Start by creating a completely controlled environment for your crop. Each facet added to increased production and better product.
    • Monitor the air temperature, air mix, airflow, and humidity. each facet added to increased production and better product.
    • Establish 16 to 18 hours of red/blue LED lighting for the highest bud growth and healthy fish. (the fish also need full-spectrum lighting)

Interesting side note: Today’s herb is of such high quality, a user rarely sees any seeds. A few years back, they were added to increase the weight. Now, the seeds are removed so the consumer cannot grow their own plants. With the growing state legality of marijuana in states, people are raising a few plants for personal use. Seeds are now for sale online.

  • You can buy five marijuana seeds in the price range from $35 to $100. These seeds are generally ‘femininized’ and produce only female plants which produce the buds with THC for smoking. Buy your seeds from reputable seed sellers who will only sell you feminized seeds. Search online for your seeds and find a seller you trust. 
  • Indoor growing is best because it allows the control of all the growth factors and reduces the public view of your operation. Marijuana has been grown this way for decades, and the art and science of indoor growing are well established. The major difference is that aquaponics uses fish affluent and Fish-Friendly Mineral Rock Dust as the nutrient source instead of using hydroponic’ s chemicals or soil.
  • A light-tight space where the lighting is controlled by timers is the most effective. The red/blue LED light fixtures are available from many sources and yes, they are expensive. When growing a single crop consistently in the same space, it will always be costly, and it needs more care and attention. Plus, you will have a slight cost-uptick in your electrical costs.
  • We are starting with the growing medium and the Grow Tables. The best depth for growing marijuana appears to be 10 to 12 inches (25 to 30cm). The medium is less critical and the use of clay pellets (expensive) or ¾ inch (1.9cm) gravel are both equally effective.

Important note: Medium, especially gravel, is HEAVY. A Grow Table 10 inches (25cm) deep by 6 ft x 32 ft (1.8 x 9.75) will weigh several tons. Build the Grow Tables to support that weight. Wherever the Grow Table is resting, needs to be very sturdy and preferably installed on concrete..

The flood and drain method of watering the crop (filling the Grow Table and draining the Grow Table) produces the best conditions for healthy root-systems, top growth, and full maturation of the plant.

In nature, marijuana prefers a sandy soil that receives water regularly and then drains quickly. The medium (gravel or clay pellets) used in the aquaponics’ Grow Table retains the moisture for a full day, plus, the large gravel or clay pellets stay moist. Cycling the available water once a day is adequate. This timing allows the roots to be exposed to air most of the time. The plants grow faster and healthier using this once a day watering.

Providing water for an hour or two (two full cycles of flood and drain) early in the morning provides all the water and nutrients the plants can use for the day. Set the Grow Table to drain fully twice and make sure the fill water stops just as the second draining begins. This timing allows most of the water to drain out, so the roots are not sitting in water all day.

Growing Medium for seedlings to be moved into a Grow Table.

The only additional nutrient you may want to include is the FF-Mineral Rock Dust that provides the micro-nutrients necessary and does not add aluminum (retards root growth) or nitrogen (fish effluent provides ample nitrogen) to the water.

Fish Friendly (FF) Mineral Rock Dust provides aquaponics’ growers the perfect balance of four major trace elements not consistently available from your fish poop. Growing flowering herbs that blossom in aquaponics flourishes with the addition of FF Mineral Rock Dust. For example, it is widely used for growing tomatoes, peppers, beans, cucumbers, etc. Your marijuana plants will receive the nitrogen from your fish poop. The calcium, iron, magnesium, and potassium are available from the FF Mineral Rock Dust and 57 other trace elements that promote plant growth. FF Mineral Rock Dust is best applied to the seedlings during their sprouting stage prior to installing in the Grow Table.

The fish effluent is an ideal nitrogen and trace element and fertilizer source, so you can use any warm water, freshwater species of fish you want, including catfish, tilapia, perch, crayfish, prawns, and others. Make sure you can buy the feed for them before choosing your fertilizer source.

One more suggestion that may be the hardest for you to pull off. Raise two crops of lettuce in the Grow Table before you plant and grow your marijuana plants. The Grow Table bacteria needs to cure, and the lettuce is a quick easy crop that will help the medium cure to prepare it to produce a great crop of herb. Lettuce only take 28 to 35 days to mature, and the wait is worth the effort. Besides, you can eat the lettuce while you wait for the system to cure.

Good luck, and if you have specific questions on any of the information in this series or want to start your own Portable Farm, please send us an email so we can respond.

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