Category Archives: Builds

The Fridgegrow – closed loop growing with co2 support

Weed in a fridge

Flowering cannabis in a fridge
Cannabis that was grown in a fridge using the fridge grow

So when people think about starting to grow weed, they usually look at it from the beneficial side: It would cost less than the shady park vendor or the dispensary in nearly every case, especially when quality is taken into account. The overall quality is more controllable. Plus: In a world with PGRs, terpene spray, brix or artifical cannabinoids its still recommended by me to rather grow at home, than buying stuff simply because the packaging looks shiny.

The fridgegrow controller tries to fill a gap in the homegrow segment. Its not a fullblown all-in-one closet where you have little to no options in terms of light or nutrition, but its also not a tent, where you usually have to deal with environmental values as they come. When the door to the fridge is closed, its not possible to exchange air or even water from inside the fridge. (disclaimer: this is only half-true, but for simplicity we will assume this for that article.) You will have to bring some ingenuity into the operation!

The fridgegrow setup uses a few key elements to keep the environmental values in check:

The fridge

A fridge is able to lower the temperature inside its volume, without exchanging air inside the fridge. Lowering the temperature lowers the possible maximum of moisture the air can hold, water will condense on the cold backwall of the fridge and trickle down…
The fridges total power has to “work” against the grow lights total power, and therefore should be able to “outfreeze” the heat.
The fridge is not included in the system. I recommend to buy a beverage fridge for commercial usage with a closed front. You want to keep the light out. Make sure, that the fridge has as much power as you can get. Its easier to hold the values this way. Heres a fridge from amazon with a clear front, that has to be masked first.

A small heating element

A heater is able to work against the fridge to keep the relative humidity up. In a perfectly dialed in fridgegrow setup the heater will almost never run during the light-on phases, because light and fridge should cancel each other out AND holding onto certain humidity levels while doing so. This is also dependend on the total amount of water inside the fridge chamber.

The perfect light – crescience modular fluXengine LED built

There is no reasoning here for anything else than a high efficient LED setup. No asian amazon light or HPS light will be acceptable if your plan is to grow cannabis in here. Make sure you are able to remove the driver and try to place it outside the fridge. One thing I love about that built is, that I get to chose the light, and its not prebuilt in here!

LED grow light and flowering cannabis in a fridge
Crescience DIY LED setup -3x fluXengine board-style repping the Samsung LM301B chips aswell as a Meanwell – ELG-150-24A

For my fridge I have chosen a modular LED solution by Crescience. Crescience is known for their modularity and compatibilty to standardsized aluminium-framing. Its super-easy to build and you can actually achieve tailored photon-outputs for every system ever.
I am running 3 of their fluxEngines (link goes to the updated lm301h version) powered by a Meanwell ELG-150-24-A Driver.

Some thoughts about the fridge-light-interaction

The principle of continuity says: What goes in has to come out. This is true for everything that has a flow to it. In the case of the fridge one puts energy as heat into the system via the grow light and the heating element. The vapor-compression element on the back of the fridge is able to get heat out of the system and will transport it away through the heatpipes on the back of the fridge. Thats also the reason a fridge is hot in the back and cold inside. Our limiting factor for our light is the fridges compressor efficiency. If our fridge cant transport the heat away through its compressor the inside of the fridge will heat up endlessly, which will result in darkness since the controller will always try to save the plants, no matter if its “daytime” or “nighttime”. This means we need the most efficient and cool running light setup in here. A commercial beverage fridge for business will have a power draw between 90 and 150W from the wall. The light you use should draw a bit less than that.

Air circulation

Small fans directed at the back of the fridge are also an important element in this setup. It keeps the watercycle running smooth and steady. I have chosen Arctic 120mm PC-Fans . I connected them via a 4-way 3-pin fan-connector in parallel and a 12V/2A powersupply. If you are not sure about that, ask an electrician how to wire it.

fans in front of a fridge grow
Arctic PC-Coolers keep the air circulation going in the fridgegrow.

vertical nets or other vertical scrog systems

Keeps your growth in check! I had a few leafs touching the backwall of the fridge keeping the water from dripping down. This results in considerable pieces of ice in there, although its almost 30°C while the lights are on! Ice is bad. It binds water and takes it out of the waterloop.
I gave my plants only 4 glasses of water – in 67 days of growing. And this is a problem.

Scrog in a fridge
Basket-ScrOG system – the grow-space is very limited, so you have to expose as much buds as possible to direct light.

Feeding plants in a closed loop system

While a small windowsill plant doesnt need much to stay green and vital, cannabis under a blasting sun-replacement will transpire significantly more and will therefore have a much increased need of moisture. The trick is to catch the condensing droplets from the back of fridge and guide them back into the pots. Even if youre not able to do that perfectly, the water will still stay in the system, because of the fridges isolation. All you need to do is to close the small hole in the lower back of the fridge, where drops usually get vaporized through the compressor on the back. We dont want that, so we close the loop with a sheet of metal, guiding it back into the pots. This also has disadvantages: Im used to give diluted water-nutrition solution to my plants. Bio Bizz usually is diluted in a way that about 1-5ml of nutritional concentrate gets mixed with one liter of water. This is of course only true for system where the soil can dry out a bit and this wont happen in a fridge setup. You have to put in higher concentration (same amount of nutrition but on a glass of water) or you go for solid nutrition like greenhouse feeding or pre-grow formulas like Biotabs Organics.

I hold my plants in 3 gal smart-pots. Pathological amounts of greenhouse bio bloom and some biobizz was given, but i wasnt really able to conquer the ramping deficiencies my plants developed.

nutrient defincency on cannabis plant in fridge
Leaf discoloration and washed out leaf-tips: this plant was craving for nutrition.

Controlling CO2 – hacking sodamax/sodastream bottles

This is the first setup I was able to make use of extra CO2 inside a grow room. You first need to buy a CO2 bottle, that gets usually used for gassing up beverages mixed together in the kitchen. This bottle is under a standard pressure of about 6 Bar. The first connection has to go to a pressure-bottle adaptor. This adaptor is then connected to a pressure-reducer unit. The reason for that is the next element: its the actual CO2 valve that lets CO2 flow into the system: The CO2-magnet-valve that can be controlled electrical by the fridge-grow controller.

pressure limiter system
CO2 pressure-reducer: left you can see that the bottle-pressure is below 1BAR, so it will have to be replaced soon! On the left is the pressure measured, that lies between the magnetic-valve and the pressure-reducer: theres still CO2 available! But a second bottle would come in handy…

The Fridgegrow-Controller

This is the heart of the system. Its basically a mixture between a server (with a UI to check data and setup the environment ) and a controller. In principle the controller is just turning bluetooth-powerplugs on and off whenever temperature, humidity needs to be dialed in, lights to be turned on and off, or to open and close the CO2 valve. The system is pretty much plug and play and can be setup even if youre not really techsavvy.

fridgegrow controller
The fridgegrow-controller . In the back you can see the droplets of water that will eventually flow back into the soil. On the right-hand-side of the controller is the casing for the temperture and humidity sensor.

The controller will react to different parameters that are more or less dependent on each other. It will find a more or less stable cycle dependent on set values and the amount of water in the system.

Fridge-control

The fridge reacts to two central reading: humidity and temperature. It will turn ON when ever the current humidity rises above the set value AND the temperature is high enough.
In this case that means that the temperature is at its set level or at max. 2x below the set hysteresis. A hystersis-value is the margin a value can go above or beyond.
So if you setup the fridge to hold a temperature between 24°C and 28°C (Thats 26°C with a hysteresis of 2°C) and relative humidity between 65% and 75% (set 70% with a hysteresis of 5%) the fridge will only start running when the humidity exceeds 75% while the fridge is between 22°C and 26°C.
The fridge will turn off when values below 70% relative humidity are reached or the temp drops below 22°C which is 2x the hysteresis. You can see easily that reaching the right relative humidity is dependent on the amount of water in the system. The fridge will never get below certain values if theres too much water to condensate.

Light control

This one seems easy: It just switches on and off at set-times.
But the system is also inhibitng fail-save measurements to save the plant. And heres the tricky part. The fridge can actually overheat while its trying to find a cycle, and thats a nono for the controller. It will turn of any heatsource that exceeds the global temperature limit. And thats the set-tempreature plus 2x the set-hysteresis. So in a running system with a 26°C ± 2°C the light will go out when ever the system breaks the 30°C limit to save the plants.
This can actually happen when theres not enough water around to keep humidity high: the heater will run longer to increase the amount of water in the air and will hit the temp-limit before the humidity levels can be reached. This will perodically lead to on/off cycles of the lights! So be aware of your cycles!

CO2 and Heating

CO2 is kind of entangled from the rest. The gas wont interfere with temperature and humidity and will be dialed in by the controller according to the set value and hysteresis.
The heater is your last bastion to figure out your values/moisture levels in the system. If the controller thinks, that a the heater needs to run WHILE the lights are on you have one of two problems:You need less water in the system!

LESS WATER or MORE LIGHT
The heater only reacts to temperature, so it will only go on, while the temperature drops too low. This can only be the case when the fridge runs too long against the light, trying to reduce the humidity. If you can dial up the light to create more evaporation the fridge will have a harder time reducing the temps, keeping the heater off.
If theres no use to it, and the humidity levels wont fall of with a constantly running fridge and a constantly running light, you have too much water in the system, so try to remove some. But this is basically the equilibium you want to achive: Running heater only when the lights are off, trying to get a stable water-humidity-temp equilibrium going.

The fridgegrow-app

One last word about the fridgegrow-app. To set everything up you need to be connected to the controller via the app or the controllers local webiste. If you dont connect the controller to your local wifi (which i recommend for safety concerns) you have to use the internal wifi from the controller. The controller guides you through the first setup of the remote-power plugs and is pretty easy to use with a standard UI and graphs of the sensor-data. Perfect for a nerd-grower like I am! In the graphic below you can see that i turned on three graphs, temp, hum and CO2. In the graphic you can see the exact moment when I opened the fridge at 19:15 or 7:15pm. the humidity and CO2 drops significantly as I pulled everything out of it, when I opened the door. The CO2 controller will turn on immediatly while you can also see the heating element tries to work against the fridge to keep the temp low.

screenshot of fridgegrow app
View through the fridgegrow app – setup your controller, check your values – remotely

Wrap-up: Should you buy a fridge grow?

For the beginners: Yes, its possible to just watch and learn with this system. Its really an accomplishment and a good amount of work to have it running stable for the first time, but you will be given a system were you have full control of every aspect of a run, while still be able to hold smell and noise in place.

Its for the nerd who grew weed in the past, but maybe dont want to have the whole fan/tent etc. infrastructure in his family home anymore. Maybe you want to get most of a limited space? This system got you definetly covered. I will try to harvest 100g dry regurlary out of there, and this should be enought to supply a single consumer out there and I am convinced that this system is working since I got my first 60g of Humboldt Seeds OGKZ out of there and it was a more than decent smoking experience. Welcome to the 21 century growers!

Quantum Board grow tent: 80 cm x 80 cm

This build is adressed to new growers from the EU with corresponding product links. Start your grow today.

Complete build to grow cannabis at home
Full build of the 80 cm x 80 cm grow tent with 25l pots.

Everything you need to harvest  ~10 oz. of dry material every 3-4 months!
I will list the items that are absolute mandatory to grow first. There is a list with additional items, that I deem useful below. Get started on your first grow tent!

General Assumptions regarding your grow

  • Your grow medium of choice is soil.
  • You grow in a grow tent.
  • You start from seed.
  • You are a grow enthusiast who wants to make the most of a given space.
  • You do not have to run this hobby on a budget. (Options for that below)

List of items

TypeItemQty.PriceLink
grow tent3×3 Grow Tent154,95 €amazon
light*260W HLG QB1319,00 €todogrowled
pots19 l smart pots433,96 €amazon
soil*100 l Light Mix128,70 €amazon
nutrition*Trypack113,68 €amazon
ventilationClip Fans1-230,96 €amazon
filtersystem*
ACF+fan+tube194,90 €growmart
clima controlTemp./Hum. Monitor18,95 €amazon
on/off switchProgammable timer112,85 €amazon


Tot.597,95 €

The light – Quantum Board LEDs

The top notch grow LED technology. The set from HLG comes with every part you need tohook up your light. Check out the build instructions from LED gardener how to do this. 

Parts to build a QB LED light
Driver, cables, wago connectors – everything is prepacked in this DIY kit.

The set is particulary inexpensive for the power you get: 260 W of one of the most efficient lights out there. The board has the famous Samsung LM301b chip on the boards. With the driver running at 100% you can expect up to 2.61 µmol/J and over 170 lm/W. You can even ramp that up with two of the kits running both at 200 W. Read more on LED tech in the theory section.

The kit also comes with predrilles heatsinks to passively cool down the boards. This is possible since there are numerous chips far apart from each other on the board, so heat dissipation is easier. One more advantage: Light is distributed much more evenly across the canopy area. In my opnion (11.2018) Quantum Boards are the single best technology for homegrowers right now and HLG are on top of the game.

Soil and Nutrition

This is an optional choice but I had very good results with the products from BioBizz before. You can also choose an alternative like Kanamu Pacha, Canna or Plagron. Read carefully the nutrition and soil usage instruction. Overfeeding is one of the biggest problems for new growers.

The Filtersystem

Air circulation is key to have optimal temperatures inside your grow tent. Room temperature between 19°C and 22°C are very much optimal for a grow room. The light, no matter if LED or HPS, will create dissipative heat through the process of creating light and of course the photon output. Its necessary to get this air exchanged at least once every five minutes. A good fan will do this easily. Remember that the use of an active carbon filter will reduce the overall power of a fan, so you need to consider that when planning a grow room.

Active coal filter and fan combo
Air gets sucked through the active coal unit out of the tent. 

Do you need active intake? Not necessarily. A powerful fan will create negative pressure inside the the tent and air gets sucked through the gaps of the tent inside. Thats more than enough for a homegrower.

Additional Items

Model builders syringes

It can be hard to get the right amount of nutrients out of the bottles. Use syringes to get it right.

Watering can

I mean, a simple container that can hold 5-10 l of fluid will work, but a normal watering can will ease up the process significantly.

pH test kits

Tap water is oftentimes not suitable for watering cannabis in an optimal fashion. Try to keep track of the tapwateres pH levels and change it accordingly. The pH for soil grows can be buffered through the grow medium itself, but it is helping alot if you can dial it in before putting it in.

pH levels for soil grows should be between 6.0 and 6.5.

Sharp gardening scissors

Keep your stuff clean and only use it for plants. This prevents infections and pests from entering you grow area.

Setup for the regular smoker – the 2×2 tent

2x2 grow tent

This setup is for you if…

  • … you consume 2 to 10 gr a week.
  • … you want to get a sneak peek into the hobby on a budget.
  • … if you dont have much space to grow.

Item list

TypeItemQty.price / $link
grow tent2×2 grow tent150amazon
light135 W QB by HLG1190amazon
potsSuperroot Airpots451.5amazon
soil50 l Light mix116.35amazon
nutritionFox Farm trio soil145amazon
ventilationClip fan114amazon
filtersystemActive Carbon Filter126amazon
climate controlInline Duct fan120amazon
on/off switchProgrammable Timer112amazon
tot.424.85

How to save money

This build should be an entry level one. It is possible to save money on different items here. 

Save money: Different light

The light listed above is (in my opinion) the best possible solution for that grow space. (Read more about light)
You can take ANY BLUE/PURPLE LIGHT YOU FIND ON AMAZON thats listed for “300 W” and replace it. It will only cost 1/3 of the quantum board, but will yield up to 40% less! The investment is an important one, but its totally fine to start with less.

You can also use an HPS light like this, but I would not recommend it in regards of effiency and spectrum. 

Save money: other distributors, trypacks and more

You can easily find a tent for less than that. Did you check craigslist or ebay? People often want to get rid of their systems! Tents also are not worth to spend alot on, since they are all pretty much alike.

Try to find a try pack of nutrition. If it is marketed as cannabis nutrition, it is pretty much okay. Just inform yourself about organic and mineral based nutrition and whats better for you. Organic grown products tend to have a better quality but smaller yield, mineral based nutrients need to be flushed out proplery but yield more. (in general..)
Try packs often cost less than $20 and will be more than enough for your operation.

The airpots im recommending have the best oxygenation properties and are able to air-prune roots to prevent rootrot or rootbounds. The pots are expensive. You can also use $2 plastic pots. Just drain your water properly and you are fine.

If you find other types of soil marketed at cannabis growers and cheaper than my option, just google the brand and read what other growers did with it. I suggest growdiaries.com for honest reviews.

If you buy a $70 light, find $20 try packs of nutes, use a different soil for $15 and the cheapest pots ($2) you can start with about $230.

Setup for the Avid smoker – The 3×3 grow tent

Grow tent in full flower
You can do this, with a setup described in this section. Source: homegrow-pro.com

Everything you need to harvest  10 oz. of dry material every 3-4 months!
I will list the items that are absolute mandatory to grow first. There is a list with additional items, that I deem useful below. Get started on your first grow tent!

General Assumptions

  • Your grow medium of choice is soil.
  • You grow in a grow tent.
  • You start from seed.
  • You are a grow enthusiast who wants to make the most of a given space.
  • You do not have to run this hobby on a budget. (Options for that below)

List of items

TypeItemQty.PriceLink
grow tent3×3 Grow Tent1$90amazon
light*400W COB Light 1$600timbergrowlights
pots3 gal airpots4$50amazon
soil*60l specialized soil1$15 – $30(see below)
nutrition*Trypack1$15(see below)
ventilationClip Fans1-2$10-$20amazon
filtersystemACF+fan+tube1$90amazon
clima controlTemp./Hum. Monitor1$3amazon
on/off switchProgammable timer1$12amazon
Tot.~$895
  • Tents are great to keep control of every aspect. You can change temperatur, brightness, humidity and even simulate seasons in there! Its absolutely necessary to get your tent completely dark to your needs. If you have a closet or a room where you can manage to create pitch black darkness, you dont need a tent. The brand of the tent does not really matter. 
  • Light: Your articficial sun. Good growlights are hard to find in the LED jungle. Read more about lights below.
  • Pots: They come in different varieties. Plastic, fabric, with holes in it from 0.5 to 30 gal. I choose the airpots, because they let air move through the soil, and roots are pruned naturally at the outlets, preventing root rot or rootbound plants.
  • Soil: Do not buy common gardening soil. Cannabis roots need space to roam. Specialized cannabis soil has the right consistency and is often perfectly balanced with nutrition. You can also cook your own soil!
  • Nutrition: Personal opinion about nutrition – as long as its marketed for cannabis and does not kill your plants every brand seems legit. It is more like a personal decision what kind of nutes you use…
  • Ventilation: Moving air prevents bud rot and keeps the branches moving. That creates resistance and your plant will grow thicker and stringer. Keep the vents on 24/7.
  • Filter system: Your main exchange for air. If you have to grow stealthy or at home you do not want to have the smell leave the tent. Get one of these asap.
  • Clima Control: Really important to keep track of your values in there. You want to know the numbers. Once you know its over 34°C in your tent all the time, you know its time to do something about it. Same with humidity.
  • On/Off switch: Over the course of 100 days of a grow you dont want to hit the switches twice a day at the same time. Automate that.

*

The light

Yes, the light is the most expensive item in a grow operation. Yes, you can save money on light, but this is the best option for a grow room of that size. Its cool, quiet and runs damn bright. It has the most recent technology behind it and does not need extra cooling. But there are alternatives.

PRO TIP: You need at least 35W/ft² of high quality LED/COB light or at least 50W/ft² if you use CMH/HPS lights, if you want max out the tent potential! There are thousands of options. Just make sure its a grow light. Spectrum, PAR, PPFD values and color of light are also important properties. Read everything about the theory behind light here.

Alternative 1 – The Quantum Board

Horticulturelightinggroup.com has a very decent 320 Watt kit. It has alot of advantages like better light distributions or overall efficiency. I just did not link it as first option because it only has 320 Watts, and we wanted to get the most of our room with the given conditions. If you are able to build these lights yourself with a kit, buy these! The magic behind Quantum boards are LM56c or LM301b LED chips from Samsung. If you can find other distributors using these chips, you can go for it.

Grow tent with a quantum board
Quantum boards have an exceptional efficiency and overall light distribution!

Alternative 2 – Other LED Distributors

Its true, Timbergrowlights is just an option when in comes to LED lights. There are several chips out there that are awesome to grow weed with.
Timber makes use of Citizen CLU048, Cree CXB3590 and Vero29 COB LEDs. But other companies do it aswell!
Cobshop.net has a 3×3 kit including 4 COBs for $480, but they dont disclose how many Watts you get in the end. I assume its 200 W, so only half of my first option.

Alternative 3 – Low Budget only

I will list them here only because they work. But do not expect wonders. Im talking about the infamous blue/purple or pink lights you find on amazon.
NO, they almost NEVER deliver the amount of power they have in their names, NO you dont need just one, but at least 3 of these “300W” varieties you find online. Which one you take does not really matter, they are all ok. They only use the cheapest LED technology, including chips and drivers. If you spend $210 on three of them, you will be able to light up your tent properly. But remember to tune up the ventilation system, because three of these bad boys run pretty hot in a 3×3.

Blurple light tent
Blurple lights – They just won’t leave me alone! Low costs – low yields.

Alternative 4 – HPS lights

A 600 W HPS light will get you pretty far in a tent like this. And it costs only $130. This can reduce the inital cost significantly, but keep in mind that these light run HOT. And by that i mean shit-i-might-need-an-AC-in-my-tent HOT. The price is low, but running this shit can cost you! Save some money, ditch the AC and the pay only 2/3 to run a sweet LED light in there and pay less for your production.

Alternative 5 – Build your own COB or Quantum Board light

www.ledgardener.com, is the best source for that. There will be a guide here soon….

Soil and nutrition – Globalization and availability

If you live in Europe you have different soil companies than in the US. So while you can buy BioBizz in Europe pretty cheap, it is better to choose Fox Farm. 

The right soil is very important for your grow. Your roots want a pretty loosy, oxygenated environment. Many soil companies put peat (turf) in their soil which is very harmful to the environment. Check the ingredients, if you want to save the planet.

EU soil recommendations

US soil companies

Nutrition

Same with as soil. It seems like there is a new nutrition company out there every week. Even the breeder try to jump on the nute train and handing out their own nutrition along the seeds. (Royal Queen Seeds and Green House Seeds for example.)

I will also only recommend nutrition that have an organic base. I just do not believe in chemicals, but thats up for discussion.

EU nutrition recommendations

US nutrition recommendations

Useful additions

There are a lot more items making your tent easier. These are nice to have, but not 100% necessary. This list is not not yet completed.

Pre-grow

  • Depending on your method of germination you will need papertowels or kitchen paper.
  • Since germination needs a dark, moist and warm environment, you might need a propagation box. I just put them in an old cookiebox on my PC.
  • Do not touch seeds! Use a tweezer.

Seedling and vegetative stage

  • Seedlings do not need flooded with water. Use a pump sprayer and be careful!
  • If you plan to train your plants, you need gardening wires or metal stakes. Or anything else you can come up with. You can also just use a cord and bind them down.
  • Use sharp scissors, knifes or even scalpels to cut leafs!
  • If you see pests like mites or thripes, treat them with bio degradable organic insecticide. Be careful with that!

Flowering stage

  • Some genetics produce fat buds. Too fat to hold them in place. Use plant yoyos or bamboo sticks and wire to hold them in place.
  • If you see any pests in the flowering stage do not spray the buds with insecticide. Use predatory bugs to fight them. This is your chance to have a personal ladybug army in your garden.
  • Jewelers loupes help you watching the trichomes and help to determine the harvest window.

Harvest, Drying and Curing