Kids Planting Day at the Mexico City Aquaponics House

The new neighborhood Kids Club “Siembra y Cosecha” (Sowing and Harvesting), for ages 5 to 15 had its kick-off event on February 26th, 2022. The event offered the children Games (Juegos), Bible Lessons (Curso), Crafts (Manualidades) and Refreshments (Refrigerio). Fourteen children from the neighborhood came to help plant seeds in the new Square Foot Garden wicking bed.

The sign announcing the Kids Club event.
The children were excited to learn how to plant vegetables and herbs.
A Father shows his daughter where to plant the seed.
Tracey helps a girl with planting.

The children painted pots to fill with planting mix and to plant their own seeds to take home and nurture.

Boy having a snack after painting his pot.

A group of children painting their pots.
A special 3-hour prayer meeting was held the night before the planting day.

The Aquaponics House is a Community Garden for the neighbors on this street. The location is used for Sunday Worship services and community outreach. Many of the residents here believe in God but have not taken the steps to live a Christian life. Tracey and John Pieters are living among them, caring for them, and teaching them how to Love the way Jesus loved us!

The Wicking Bed is the first part of a two-phase project to build a Community Garden. The second phase is starting now to build an Aquaponics System on the roof of this house. The system design has been completed but we need additional financial support to purchase the materials and equipment. Please consider contributing to this effort. Follow this link to John & Tracey Pieters – United World Mission ( or write a check to “United World Mission” and note your preference to “John & Tracey Pieters Account #27334 – Aquaponics”.

Wicking Bed Build at Mexico Aquaponics House

The Mexico City team has the Wicking Bed ready to plant seeds of hope and fresh food in the new community Aquaponics House! Thanks to Tracey, Luis, Jerry, and John. This is the first phase of the system build. (The second phase will be the Aquaponics grow bed and fish tanks on the roof!)

The Mexico City Team:
Tracey, Luis, Jerry, and John

The Wicking Bed is made from standard concrete blocks setup in two rows.

The bed is lined with food safe LDPE plastic, then insulated with 10mm (3/8”) Styrofoam (Polystyrene) on the bottom and sides. The Styrofoam protects the plastic liner and stabilizes the temperature. Water is added to the bed through a 100mm (4″) pipe along the bottom (drilled with holes) that is covered with volcanic rock (Red Tezontle) on both sides. The rock helps improve the water dispersion into the bottom of the bed and stabilizes the pipe.

Luis and Jerry add a 100mm (4″) layer of course horticultural vermiculite to cover the pipe. This creates the water reservoir. There is a 19mm ( ¾”) PVC pipe through the side to allow overflow if the water reservoir gets too full after rain.

A layer of shade cloth or geo textile cloth is placed on top of the vermiculite to keep it separate from the compost.

A 254mm (10”) layer of well-aged compost is added and then topped with a 50mm (2”) layer of straw mulch.

The top edge of the cement blocks will be left open. The excess plastic is tucked inside over the Styrofoam lining. The exposed holes can be filled with planting media and used to grow companion flowers that attract beneficial insects. Another option is to place Trellis posts on the northwest end in these holes for climbing plants like Cucumbers, or beans.

Row covers will be used to protect the plants from heavy rains or cold temperatures during winter.

John and Tracey Pieters are Christian missionaries with United World Mission in Mexico City, Mexico. Their vision is to create a complete Aquaponic System to bring people together, sharing labor, life stories, pure food, and the joy of knowing Jesus Christ.

You may support John & Tracey financially by clicking John & Tracey Pieters – United World Mission ( or write a check to “United World Mission” and note your preference to “John & Tracey Pieters Support” (Account #27334).

Aquaponics Design Certification

Completion Certificate

With thankful hearts, we Praise God for blessing us with the opportunity to attend Murray Hallam’s Aquaponics Design Course and to receive the commercial systems design certification. The 8 week online course included 5 to 8 hours of weekly video instruction, quizzes, and class discussions. The course required the submission of a complete system design. We presented the detailed design of the Mexico City Aquaponics House where John and Tracey Pieters are Christian Missionaries. Their vision is to create a complete Aquaponic System to bring people together, sharing labor, life stories, pure food, and the joy of knowing Jesus Christ. Murray Hallam commented on our design, “Altogether, an extremely well-prepared Aquaponics Project plan.”. We’re looking forward to working with John and Tracey to bring this plan to reality!

Small-scale aquaponic food production: Integrated fish and plant farming

I highly recommend this technical paper published by the Food and Agriculture Organization of the United Nations. It provides a complete reference for small scale aquaponics and shows how to build three small scale systems using IBC Totes.

Somerville, C., Cohen, M., Pantanella, E., Stankus, A. & Lovatelli, A. 2014.
Small-scale aquaponic food production. Integrated fish and plant farming.
FAO Fisheries and Aquaculture Technical Paper No._589. Rome, FAO. 262 pp.

I’ve attached a PDF of the “Aquaponics quick reference handout” which begins on page 249 of the technical paper. This 18 page handout presents the chapter summaries and key technical information. Read this first to get an overview of the entire paper.

Yikes! Aquaponics Water pH Crashed!

The fish had not been eating as much and the plants were not growing well. A crop of Butterhead lettuce seedlings all died within two weeks of being rafted. Something was wrong.


I’ve been operating my backyard 48 square foot deep water culture Aquaponics system for about 4 years now and have never seen these combination of events. The plants had been growing well and the fish active and eating. I had gotten complacent and was not checking water quality regularly. The first test sample revealed a high ammonia level of 4 ppm, and the pH reading was 6.0. It appeared that the nitrification process had stopped working and suspected the pH was lower than 6.0. I realized that 6.0 was the lowest reading either of my test kits could measure so I purchased an electronic meter pen for about $10 that could measure pH from 0 to 14.

pH Pen
pH pen measures from 0 to 14 pH

Yikes! The pH is 4.50! This is too low for my Tilapia, plants, and bacteria. It should be between 6.2 to 6.8.

The Solution

Searching the internet I found an informative article written by Sylvia Bernstein titled “Managing pH in Aquaponic Systems“. In this article she points out that during the life of an Aquaponics system the pH will naturally go down as a result of the nitrification process. She says, “…the nitrogen cycle actually produces nitric acid, which will naturally cause your pH to go down. ” She explains that the hardness of the water “dictates the buffering capacity”. I’ve been keeping a mesh bag full of crushed eggs shells in the system to supplement the calcium, but it has not been enough to offset the production of nitric acid.

Following her advise, I checked the water hardness and found carbonate hardness (KH) was around 5 dKH (or 89.5 ppm) and general hardness (GH) was at about 358 ppm. So the buffering capacity was adequate to raise the pH by adding calcium carbonate and potassium carbonate.

One last check of the pH measured 4.90 (water was 72 degrees F). This system has a total water volume of about 560 gallons. Not wanting to move the pH up too fast I used what was recommended to treat 200 gallons of water. I added 5 teaspoons of each powder into two separate glass pint jars of system water and stirred until dissolved. I slowly poured out the first jar over the air stone at the end of the first trough where the fish tank water flowed into the trough and waited for it to dissipate into the water. Then I slowly poured in the second jar.

The next day (about 16 hours later) the fish tank pH was 6.00 and the troughs were 6.22. Problem solved. I’ll monitor daily and add a little more to move the pH up to around 6.5.

Lessons Learned

  • Check the water quality at least every three months and keep a log of the results.
  • Use a pH Pen meter that goes from 0 to 14 pH.

First 72 Seedlings Rafted at TOL site

In less than a week the first crop of Butterhead and Red Romaine lettuce has sprouted! Rebecca’s helper used a fork to gently lift the seedlings from their cells and place them into the netpots. The netpots are floating in 2″ thick foam rafts

Two 36 hole rafts filled with seedlings.

Tilapia Fingerlings Added to the TOL System

Today the Aquaponics grade Blue Tilapia were delivered from Lakeway Tilapia and added to the TOL system. The system water tank was 82 degrees and the shipping water bag was about 78 degrees. The system water was pH 7.5 and the shipping bag was pH 7.8. So everything looked good for adding the fingerlings to the system tank. After the Tilapia grow bigger then 15 will be removed and moved to another system.

Short video of the Tilapia fingerlings.

First Lettuce Harvest of 2019

Johnny's Selected Seeds packet

I planted 36 TRUCHAS OG MTO seeds from Johnny’s Selected Seeds on 1/5/2019 in a 36 cell propagation tray using a 60%/40% mix of Coconut Coir/ Vermiculite as a planting media. I’ve found that these seeds germinated better without the use of a propagation mat (or heating pad) with an optimal surface temperature of 68 degrees fahrenheit (F). The sprouts began to appear after about 5 days.

After 11 days under the grow light for 14 hours per day I moved the seedlings into 2″ net pots in the 2-inch by 16-inch by 24-inch STYROFOAM XPS floating rafts. These plants grew well in my aquaponic system even though it was 55 days from rafting until harvest. The seed packet says 47 days to maturity but we only use Sunlight in our backyard greenhouse and the Winter days have been short. The temperature in the greenhouse typically stays above 40 degrees F during the night and can reach 85-90 degrees F during a sunny day.

It took me about 14 minutes to harvest 29 plants on 3/22/2019. (We had harvested 7 earlier for meals). The plants were dense and weighed about 4 ounces each. In total, the harvest produced 7 1/2 pounds of lettuce that filled 10 1-gallon bags.

After washing and bagging, I delivered 9 bags with three heads each to Tree of Life Ministries in Purcellville, VA for distribution to families the next day.

God Bless you! Thanks for reading.

A Bouquet of Kale

My Niece Allie loves Kale so we gave her a bouquet to take back to college! Fresh cut organic baby Kale from our Aquaponic garden. Kale grows great in the cold – the outside temperature was in the low 30s (F) last night and the green house was about 45 degrees Fahrenheit. I’ve been cutting a big handful every morning when I go out to feed the fish. We use it in smoothies and salads. I’m amazed how long it lasts in the fridge! I’ll fill a gallon bag full and it stays fresh for at least a week or two.