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It’s about time for an update on my hydroponics system.  This is a follow up to my last update.

The goals of this post include:

  • Changes from last posting
  • Corrections made and lessons learned
  • Next steps
To sum it up, the plants could be growing better.  I have made “mistakes”.  This is becoming and excellent opportunity to learn.  I will be applying what I learned here to future efforts and will report results in subsequent follow ups.

Changes from Last Posting

Last time I had two buckets.  One with a tomato plant.  Now I have one.  The story of how this happened follows.

Cracked Lid 


 crackedLidSm  Algae
 cracked lid and big holes for measurement (not shown)…. leads to algae

  I did an “oopsy” with the tomato plant bucket.  As I was lifting the lid off to change the water, the lid cracked pretty much in half.  I put the lid together (or so I thought) and went to Lowes to get a heavier lid.  I shouldn’t have been surprised that the tomato plant fell into the bucket.  Unfortunately, the plant did not survive this dilemma.  So one bucket down, one bucket left.

Roots

roots

I’m happy the roots look really good!  Nice and white – no browning.

Environmental Readings

The environmental readings were:

Humidity Air Temp Water Temp Color Temp LUX pH TDS
40 72/65 77 3715 29887 4.1 2070

Air Temperature

The air temperature while the light was on (day temperature) averaged at 72F.  The night temperature averaged 65F.  I take this to be within the recommendations given in  Hobby Hydroponics (p. 17):

They [cucumbers] take about 2 days to erminate under a day temperature of 79°F (26°C) and night temperature of 70°F (21°C). Upon transplanting to the growing blocks the temperatures may be lowered by about 5°F (3°C) to give a day temperature of 73°F (23°C) and night temperature of 68°F (20°C).

Water Temperature

The water temperature is being controlled by a water heater.  77F seems too hot to me.  Besides, algae loves the warmer water.   When I move the cucumber to a new bucket I’m going to stop using the water heater and see how it goes.

LUX

At this point, I am still exploring “the best” LUX values for the plant leaves (and eventually the flowers).  I figure the lower I can go and still produce a great harvest would save money on the cost of LEDs as well as the ongoing electricity cost.
 
In an earlier post, I noted Super Angry Guy’s advice on LUX values for the different growing stages.  Hobby Hydroponics (p. 23):

As mentioned earlier you want a minimum intensity at leaf surface in the upper portion of the plants of 5500 lux (510-foot candles) for a period of 14 to 16 hours per day.

Color Temperature 

One of many great recommendations from Super Angry Guy on the hydro subreddit:

The optimal color temperature for plants depends on the specific plant, the stage of a plant’s life cycle and the light intensity. With CFL the standard good rule of thumb is veg at 6500K and flower at 2700K. 

I don’t believe my LED array with one array being cool white and one being warm white is ideal.  Rather, since I had zero experience with LED arrays – let alone building an LED system, I was more interested in the process of picking out the chips, outlining the parts needed, and building the circuit plus the reflectors and method to raise the LEDs as the plants grew towards the light.  I’m still exploring different LED white / red / blue combinations.  For now, I’ll leave this setup alone.

pH and TDS

Sadly, I have been lazy about checking the pH and nutrient levels.  After taking a pH reading, I found the level was 4.1 – way to acidic.  I added pH UP and bumped the pH to 6.1.  The TDS was 2070.  I noted in This post, values around 1200 and 1800 are best for cucumbers.  I lowered the TDS to 1500 by dumping out some of the nutrient water and replacing with filtered water.

Yellow and Torn Leaves

Why are the leaves yellow?  What causes the tearing.

CukeUpdate

 

I asked on the hydro subreddit and got great advice from theUrbanGreenhouse:

[–]theUrbanGreenhouse 1 point 6 days ago

Like I said, potassium is what I would go with first. Don’t trust it until you see results for yourself! I use Canna’s two-part solution for hydro Aqua Vega A and B. A is a 5-0-3 and B is 0-3-4. Because you are instructed to mix in equal parts per gallon essentially I’m using a 5-3-7. I don’t know Dyna-Gro but that seems like an odd NPK. The N and K values are normally the highest as they are the most important for growth and bloom.

I’ve held my pH values at around 4.5 for an extended period of time and didn’t see any negative effects until about the 4th day. And this is in aeroponics, which supposedly develops deficiencies quicker than other methods as it does not have a constant solution there to act as a buffer. I was curious to see what would happen because I always hear that lockout caused from high/low pH can be a rapidly developing problem. Now that I know it takes a while I only monitor every 2 days, if I remember.

I’m not sure what to say about the TDS readings. TDS is actually a factor of the electrical conductivity, or EC. There is a conversion factor that most instruments multiply the EC by and display this number as the TDS. With NaCL conversion factor (700) your 2070 is 2.95 EC and with the 442 conversion factor (500) it is 4.14. So yeah, both of those seem a little bit high. this page that /u/thews posted a little while ago says cukes like 1.7-2.5 EC. Given that info, I would probably let it sit for a couple days at your new pH. With your TDS levels there should have been plenty K in the solution, it just might have been unavailable due to the low pH.

 

Lessons Learned 

DWC

  • stay away from cheep bucket lids.
  • make sure the bucket is as light tight as possible.  That darn algae will grow quickly grow where there is water, nutrients, and light.  The hole to hold the air pump, water temperature sensor, and TDS meter let in two much light.  Cracks in the lid did not help.  Moving forward, all aspects of the bucket should be black to eliminate light leakage.
  •  Best if bucket and lid are black to minimize the chance of light coming through the lid or bucket.
  • DWC buckets are difficult to open up the lid and check what is going on or clean the bucket.  I recently started reading Hobby Hydroponics, Second Edition.  I decided the author – Howard Resh – had a lot of practical advice to give after a helpful person on the hydro subreddit gave me advice that came from his book.  The advice made a lot of sense so until my explorations show otherwise, I’ll keep reading and factor in what Mr. Resh’s knowledge.  In the case of cleaning a DWC system, he recommends once a month.  These buckets are heavy and I have them in a location that makes it awkward to easily move.  I am rethinking the DWC method and probably will move to systems in which many plants share a reservoir.  
  • I must use the appropriate space and (net) pot size.  I used a small (net) pot for the cucumber and cramped it in with other plants.  While I got a variety of cucumber that is supposed to take a smaller space, it’s leaves and size are too big for a 5 gallon DWC holding 3 plants.
Environmental Reading 
  • Pay more attention to the readings and adjust as soon as possible.  I really need to finish up the hydroponic sensor node and get it to a form that can more robustly be included within the hydroponics systems.
  • Keep learning about nutrients for hydroponics.  Nutrients is a large and very important component of growing hydroponically.  Providing nutrients means I can have a better control in feeding plants the nutrients they need and understanding what nutrients are lacking.  However, this doesn’t matter as much at my current level of understanding.  

Best way to gain experience

I learn best by jumping in and splashing around.  Observing what others have done.  Practice, practice, practice…and then reflection.

  • The Internet has evolved in its community support such that n00bs like me can absorb advice.  And as I learn, share what I have learned with other n00bs in the community.  The hydro subreddit has so far been the best place to read what others are doing as well as bounce ideas and challenges I am having.  Many of the responses point me to products or methods I would have not as easily have found.
  • I have not been a great learner from subject matter books (like textbooks!).  Since I do not have the context or relevant experience to help me comprehend what I am reading, I don’t absorb much of what I have read.  The exception has been after I had read some articles found from a Google Search, watched some relevant YouTube videos, and then checking out a book or author that was recommended.  Currently, I am reading a book by Howard Resh.  In the future, I might not find his information that useful.  For now, he brings up many “do’s and donut’s” as well as techniques I would not have known without reading a book of his.

 

What’s Next

The Cucumber Plant

The first thing will be to transfer the cucumber out of the 5 gallon tank with three plants and put it into one that holds just the cucumber.  The plant is growing up.  It is time to support the vines as they grow towards the light.

During my hydro readings, I ran across a practical product that had a CoGs ($37) that was the same as what I paid, but I liked it better:

BucketFarm
 I bought one and after a bit of searching found the web site that goes through setting up the Bucket Farm.  It solves a few of the challenges I noted in Lessons Learned:
  • sturdy bucket lid
  • top black, only hole is for the air pump

I bought some  Aqua Vega to see if that brings the cucumber leaves back to health.  I plan to replace the Dyna-Gro with the Aqua Vega to see if this is a better nutrient mix for hydroponics vegetable growth.

Finally, I need to install a “semi-permanent” hydroponics sensor node so that I can more regularly track and more quickly respond to environmental data.

The Hydroponics Setup

  • Move away from DWC to a shared reservoir system.
  • Design out the hydroponics garden I will build.  Up until now I have been exploring what goes into hydroponics.   I will move into a phase in which I will grow the type and amount of vegetables that will provide a substantial augmentation to the vegetables I am buying.  One goal is to build a setup that will provide my family with fresh tomatoes throughout the winter.  During the summer, I would do most of the tomato growing outside.  I love of outdoor gardening and compost all year.  Every year I am delighted to see the amazing amount of worms in my compost.  It is great to have nature just do its thing with the sun, soil, and water.
  • Finalize and build the hydroponics sensor node system.  My biggest unknown is what sensor/probe to use for measuring the EC.  There are not a lot of choices as there are with the other sensors.  I also need to decide when I want to build a PCB for the sensor node and the base system.
  • Automate adjusting the pH and the nutrient/water supply.
  • Measuring electricity usage.
Until next time.

 

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