TLO Teas: The Actual Recipes, the Brewing Method — and What Agricultural Science Says About Compost Tea

AZ_Growshop_Asia · October 15, 2026, 4:34am

Aerated compost tea is the most enthusiastically promoted practice in organic cannabis growing and one of the least supported by agricultural research. The brewing method and tea formulas below are summarised in our own words from The Rev’s True Living Organics: The Ultimate Guide to Growing All-Natural Marijuana Indoors (2nd edition, Green Candy Press, 2016). A later “Druid’s Edition” (2024) also exists, and its quantities may differ. Growers using this method deserve accurate instructions. They also deserve the evidence, so that comes after the recipes.

1. What a TLO Tea Is

AACT — actively aerated compost tea. You suspend worm castings or finished compost in dechlorinated water, add molasses and other nutrient inputs, and aerate the mix continuously. The book’s beginner brew runs for about 12 hours. The full brews run for 24–30 hours in temperate conditions, and less in hot weather (see section 4).

The book explains the mechanism in two parts. First, the microbes that multiply during brewing break the amendments down into fine particles that roots can take up. Second, the microbes hold nutrients in their own bodies and release them when they die and decompose.

The method puts timing ahead of the recipe. The book says the microbial population peaks between 24 and 30 hours after aeration starts, and it treats a thick foam on the surface as the sign of a good brew. Both are claims made by the method, not established findings. Foam mostly comes from dissolved proteins and sugars, for example from molasses, kelp and fish inputs, and it has not been shown to be a reliable measure of microbial activity. According to the book, a brew left much past 36 hours is still a nutrient-rich humic solution but no longer has the large living population that was the point. The book also suggests scraping the film off the vessel wall with a rubber spatula and stirring it back in before you apply the tea, because it considers that film the most microbially dense part of the brew.

Frequency is much lower than most growers assume. The Rev applies tea only two or three times in the whole flowering cycle, at least ten days apart. He notes that growers who don’t core feed will need tea roughly every ten days. The book presents this as a step down from earlier versions of the method, so the trend with experience has been towards weaker and less frequent teas.

2. The Recipes (Summarised)

Each formula makes 3.8 L (one US gallon) of concentrate. You then dilute it with the same volume of water to get 7.5 L of finished tea. The spoon measures are the book’s US measures. The metric figures are volumes (1 tsp ≈ 5 mL, 1 tbsp ≈ 15 mL), not weights, because grams depend on how dense each material is.

Use water with no chlorine or chloramine. Rainwater, distilled water and RO water contain almost no minerals, so the book suggests adding about 15 drops of a Cal-Mag supplement per 3.8 L, or replacing about one fifth of the water with bottled spring water. The aim is to give the microbes some dissolved minerals to work with.

When to use each tea:

Vegetative tea: use it to push growth, or when a plant has to stay in a small pot longer than planned. It is not for seedlings or freshly rooted cuttings. Stop about ten days before you switch to flowering, and apply it no more than once every ten days. Pick a guano whose P is no more than one third of its N, and no higher than 5.
Early-flower tea: use it from about two weeks before flowering through the first half of bloom. Pick a guano whose P is at least half of its N.
Late-flower tea: use it from the second half of flowering until two weeks before harvest.

Ingredient	Vegetative	Early flower	Late flower
Kelp meal	1 tsp (5 mL)	1 tsp (5 mL)	1 tsp (5 mL)
Soluble kelp/seaweed powder	¼ tsp (~1.25 mL)	½ tsp (2.5 mL)	—
Alfalfa meal	1 tsp (5 mL)	—	—
Feather meal	½ tsp (2.5 mL)	1 tsp (5 mL)	—
Blood meal	¼ tsp (~1.25 mL)	—	—
Fish meal or dried fish (e.g. NPK 11-5-1)	—	½ tsp (2.5 mL)	—
High-N guano (e.g. NPK 9-3-1)	½ tsp (2.5 mL)	—	—
Balanced guano (e.g. NPK 12-8-2)	—	½ tsp (2.5 mL)	—
High-P guano (e.g. NPK 0-10-0)	—	¼ tsp (~1.25 mL)	¼ tsp (~1.25 mL), or bone meal instead
Dry organic fertiliser	¼ tsp all-purpose (~1.25 mL)	½ tsp bloom (2.5 mL)	¼ tsp bloom (~1.25 mL)
Powdered Azomite (micronised if possible)	⅛ tsp (~0.6 mL)	⅛ tsp (~0.6 mL)	⅛ tsp (~0.6 mL)
Oyster shell flour	½ tsp (2.5 mL)	—	—
Molasses (maximum)	½–¾ tbsp (7.5–11 mL)	—	½ tbsp (7.5 mL)
Worm castings	60 mL (or finished compost, or 2 tsp/10 mL worm-bin leachate)	60 mL (or 1 tsp/5 mL leachate)	60 mL (or ½ tsp/2.5 mL leachate)
Optional: insect frass or guano	1 tbsp (15 mL)	1 tsp (5 mL)	—
Optional: bee pollen	—	½ tsp (2.5 mL)	¼ tsp (~1.25 mL)

The beginner version

The book’s first-brew recipe is simpler:

7.5 L of distilled, rain or RO water
120 mL fresh worm castings, or 60 mL well-finished compost
1 tsp (5 mL) soluble kelp powder
2 tsp (10 mL) molasses
A fast-release nitrogen source: alfalfa meal, dried fish, or 1 tsp (5 mL) fish emulsion. The full method itself prefers dry fish (see below).

Aerate for about 12 hours with the water above 18.5 °C.

3. Practical Notes From the Method

Scaling up is mostly linear, except for molasses. The base recipe makes 3.8 L of concentrate for 7.5 L of finished tea. A 200 L concentrate diluted to 400 L is therefore about 53× the base batch. For that size the book suggests roughly 240 mL kelp meal, 120 mL guano and 120 mL molasses:

Kelp and guano are close to straight multiplication: 1 tsp × 53 ≈ 265 mL, and ½ tsp × 53 ≈ 130 mL.
Molasses is the exception. Straight scaling of ½–¾ tbsp would give about 400–600 mL, and the suggested 120 mL is far below that. Keep molasses well under linear.

The main risk when scaling is over-concentration. The method says it shows up as no foam.

What the method says no foam means. It lists four likely causes:

The brew is too warm, so it foamed and collapsed before you checked.
The brew is too cool, so it is slow and peaks later.
The brew is too concentrated.
There is too much high-P input, such as high-P guano or soft rock phosphate. The book says these suppress foaming even in very small amounts.

Given the caveat about foam in section 1, treat these as rules of thumb.

Use dry fish, not fish emulsion. Liquid fish products are usually stabilised with an acid as a preservative, typically phosphoric acid and sometimes sulphuric acid, which lowers the product’s pH. The method aims to avoid preserved, acidified inputs in a living brew. The book says dried fish or fish meal releases its phosphorus slowly, from the bone.

Kelp is powerful and easy to overdo. The book warns that too much kelp causes symptoms that look like potassium problems or salt build-up. It prefers soluble powders to liquid concentrates, because the liquids need preservatives.

Freshwater aquarium water is a good microbial source at about 30 mL per 3.8 L, according to the book. Only use it if the tank has had no dechlorinators or fish medications.

4. Brewing in Thailand and Southeast Asia

The book’s timings come from temperate conditions. At the 28–32 °C that is normal in an unconditioned Thai room or garden, four things change:

The microbial curve runs faster. Nobody has published a validated brew window for these temperatures. As a cautious working rule, don’t run a full brew to 24–30 hours by default. Start checking from about 12 hours, and treat the 12-hour beginner timing as a ceiling rather than a minimum. A short brew mainly loses some microbes. A long, hot, sugar-fed brew raises the risks described in section 5.
Warm water holds less oxygen. Saturated fresh water holds roughly 9 mg/L of dissolved oxygen at 20 °C but only about 7.5 mg/L at 30 °C, while microbes use oxygen faster in the heat. Use an air pump that is generously sized for the volume, and keep the brew moving.
Heat also suits pathogens. E. coli and Salmonella grow quickly at warm temperatures. Keep molasses low, or leave it out (see section 5).
Keep the brewer out of the sun and use the tea right away. Brew in shade or indoors, and apply the tea as soon as it is ready. Don’t store finished tea.

Water. Municipal tap water is usually chlorinated. Standing and aerating removes chlorine but not chloramine, so rainwater or RO water, with the mineral top-up described above, is the simpler choice.

Local inputs:

Molasses (กากน้ำตาล) and bat guano (ขี้ค้างคาว) are easy to find in Thai agricultural supply shops.
Azomite is an imported trademarked product. Fine rock dust, such as ground basalt sold for agriculture, is a common local substitute, but it is not identical in mineral content.
Bee pollen (เกสรผึ้ง) is sold as a food product by Thai beekeepers. It is optional in every recipe.
Rock phosphate (หินฟอสเฟต) is sold as a fertiliser. True soft (colloidal) rock phosphate is less common, so check the label. The method says even small amounts can kill the foam.

Use the metric volumes in the table and measure with the same spoons every time.

5. What the Evidence Actually Says

Now the part that rarely appears alongside the recipes.

Disease suppression: weak evidence. Scheuerell and Mahaffee’s review of the compost tea literature (2002) found some studies in which teas reduced certain foliar diseases. Most of the positive results came from non-aerated teas, and the evidence base was thin. Linda Chalker-Scott (Washington State University) reviewed the same literature in her “Myth of Compost Tea” extension columns and fact sheet (2004 onwards). She concluded that aerated compost teas have no scientifically documented effect as pathogen suppressors. Non-aerated teas may help against some pathogens on some plants.

Nutrient supply: inconsistent. Some studies report better plant growth or quality, probably from a quick dose of soluble nutrients, but the results have not been reliably reproduced across studies.

Safety: a known issue since the mid-2000s. Two studies found that adding sugar-type supplements to compost tea let human pathogens multiply:

Duffy et al. (2004) tested how molasses affects the regrowth of E. coli O157:H7 and Salmonella in compost teas.
Ingram and Millner (2007) used compost with very low pathogen levels. Without nutrient supplements, E. coli O157:H7 and Salmonella stayed undetectable or died out. With supplements added, they grew by 1 to 4 log units (10 to 10,000 times) in both aerated and non-aerated tea. Aerated tea sustained higher pathogen levels than non-aerated tea once supplements were present. The authors advised against supplements in teas used on fresh produce.

Regulators drew the same line. In the United States, the National Organic Standards Board (NOSB) advises the USDA National Organic Program. Its 2006 guidance on compost tea built on its 2004 Compost Tea Task Force report:

Tea made from compliant compost with no additives may be used without restriction.
Tea brewed with additives such as molasses or other sugars is treated like raw, uncomposted manure, which carries a 90-day or 120-day pre-harvest interval for food crops. The exception is a production system that has been tested and shown to meet microbial limits.

For cannabis this deserves serious attention. The product is inhaled, often by patients whose immune systems are weakened. Microbial contamination is one of the things that regulated medical cannabis markets test for, and a sugar-fed aerated brew applied to a flowering plant is a plausible route to exactly that kind of failure.

Sources cited

The Rev (2016). True Living Organics: The Ultimate Guide to Growing All-Natural Marijuana Indoors, 2nd ed. Green Candy Press.
Scheuerell, S. & Mahaffee, W. (2002). Compost tea: principles and prospects for plant disease control. Compost Science & Utilization 10(4): 313–338.
Duffy, B. et al. (2004). Effect of molasses on regrowth of E. coli O157:H7 and Salmonella in compost teas. Compost Science & Utilization 12(1): 93–96. doi:10.1080/1065657X.2004.10702163
Ingram, D.T. & Millner, P.D. (2007). Factors affecting compost tea as a potential source of Escherichia coli and Salmonella on fresh produce. Journal of Food Protection 70(4): 828–834.
Chalker-Scott, L. “The Myth of Compost Tea” columns and compost tea fact sheet (2004 onwards). Washington State University, Puyallup Research & Extension Center.
USDA National Organic Standards Board (2006). Recommendation for Guidance: Use of Compost, Vermicompost, Processed Manure and Compost Tea (Crops Committee, 19 October 2006), building on the 2004 Compost Tea Task Force report: https://www.ams.usda.gov/sites/default/files/media/NOP%20Final%20Rec%20Guidance%20use%20of%20Compost.pdf
USDA Agricultural Research Service (2006). Recommendations for a safer compost tea: Recommendations for a Safer Compost Tea : USDA ARS

6. How to Reconcile the Two Halves

Growers using this method report good results, and nobody is suggesting their harvests are imaginary. But a fair reading of both sides suggests the following.

The nutrient effect is probably real and probably modest. You are applying dissolved organic nutrients to soil, and that does something.

The microbial-inoculation claim is the weak part. The evidence does not support the idea that you are seeding the soil with a superior microbial community rather than feeding the one already there.

The safety issue is real and manageable. If you brew:

Use finished, properly composted material, never raw manure.
Keep molasses to the minimum the recipes give, or leave it out. The studies above found that pathogens did not grow when no supplement was added.
Keep brews short in hot weather and use them at once.
Drench the soil rather than spraying the plant, and never apply tea to flowering buds.
Clean the vessel thoroughly between brews.

The simplest alternative has better support. Chalker-Scott’s extension writing recommends using compost and mulch directly rather than brewing tea from them. In a TLO system you already have the compost. Top-dressing it, or core feeding with amendments in the pot, reaches much of the same nutrient goal without the culture-vessel risk.

If you brew teas in Thailand or elsewhere in the region, how long do your brews take at 28–32 °C? Do you get consistent foaming, and have you shortened the brew? Local experience is exactly what is missing from the published guidance.

This article is general educational information. In Thailand, cannabis flower is a controlled herb under the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis) B.E. 2568. Cultivation requires a licence. Flower may be dispensed only against a PT 33 prescription and must come from a GACP-certified cultivation site. Recreational use is not permitted, and flower may not be sold or advertised online. The Cannabis Control Act is still a draft (approved by Cabinet on 22 September 2026 and sent to the House).