Stuppy Aquaponics Blog

System Update: Niles 7/6/17

Posted by Conor Quinlan on Jul 6, 2017 2:30:00 PM

Niles

 

Nitrogen (mg/L)

 

 

 

Date

pH

Total Ammonia

Ammonia

Nitrite

Nitrate

Temp (Fo)

Alkalinity

mg/L

EC (mS)

6/16

7.4

0.25

n/a

0.25

150

81

150

1.17

6/19

7.5

0.25

n/a

0.25

-

81

-

1.20

6/21

7.45

0.25

n/a

0

31.5, 140

81

-

1.28

6/23

7.45

0.25

n/a

0

-

82

140

1.20

6/26

7.35

0.25

n/a

0

same

74.5

-

1.22

6/28

7.3

0.25

n/a

0.25

-

77

-

1.21

6/30

7.25

0.25

n/a

0.25

-

77.5

110

1.17

06/16/17 -> 06/30/17 : Total Hardness: 390 -> 360 -> 350 mg/L CaCO3 equ
Calcium Level: 61 -> 59 -> 56 mg/L    Magnesium level: ~58 -> 52 -> 51 mg/L
P (PO4-) = 22.5 -> 15.5 -> 12 mg/L (4 mg/l as P)

LED_comparison.jpg

An image of the size difference between the collards grown by the LEDs (right) and Fluorescents (left, smaller). The LED fixtures have the ability to produce fully mature crops 5-7 days earlier than the fluorescent fixtures. Below is a table showing the harvest times for mixed lettuce and collards between LEDs and Fluorescents.

 

LED

Fluorescent

Mixed Lettuce

28 days

33 days

Collard Greens

38 days

45 days

 The numbers above represent harvest times it takes to reach the maximum maturity. In an LED set-up these leafy greens can be harvested a couple days earlier. Overall both Flourescent and LED provide more than sufficient light for optimal growth rates with the LEDs being superior and even outpacing the recommended grow time of 45 days for fully mature collards.

Water Quality Overview

Since the clogging of the system on 6/11 and subsequent death of over half the fish nutrient and pH levels have remained steady. No additions other than 100 grams of chelated iron was added to the system in the last 2 weeks.

 On 6/20 a water sample was submitted to JR peters Lab. As expected nitrate accumulation rates have slowed. Despite the lower waste production nitrate and EC seem to be remaining stable with a recently lab tested value of 140 mg/L NO3 (31.5 mg/L as N), more than enough to support the nitrogen needs of any crop. The lab test also gave us more exact K and PO4 levels which have only been rough estimates at this point; K = 33 mg/L and PO4 = 12 mg/L (or 4 mg/L as P). Although both levels appear to be quite low, especially compared with hydroponics, they have been adequate enough to support the growth of not only the two float beds of collards and mixed lettuce but also an entire media bed filled with various heavier feeding fruiting crops including tomatoes, cucumbers, cantaloupe, squash and peppers.  Boron levels are high and are the likely reason behind the discoloration of the cucumber leaves which is sensitive to Boron. Despite the high levels of Mn added to the system via MOST micro mix, Mn concentration are still far too low at 0.05 mg/l. Deficiencies have appeared, and for this reason, the fertilizer manganese sulfate will be used to increase concentration without affecting Boron or other potentially toxic micros. Below is a table of the full results: 

Parameter

Concentration (ppm) (4/20)

Concentration (ppm) (6/20)

E.C.

0.64 mS/cm

0.99

Ca

36.91

48.53

Mg

23.5

51.83

Na

60.39

70.27

Cl

35.31

56.76

B

0.17

0.44

Fe

0

2.65

Mn

0

0.05

S

64.36

68.65

Cu

0.01

0.28

Zn

0

1.16

Mo

0.01

0.07

NO3-N

0.02

31.47 (140 as NO3)

NH4-N

6.73

0.78

P

0.9

3.96

K

10.77

32.87

Fish Overview

The blue tilapia in the Niles system continue to feed at more than the optimal rate. The feeding rate has increased from 170 grams/day to 210 grams/day and fish size has increased from 125 grams/fish to 175 grams/fish. Using the avg. tilapia weight and the data generated by the graph below it was determined that they should be feeding at 2.19%. This is 0.67% lower than their actual feeding rate at 2.86% body weight which means they are consuming nearly 50 grams more feed than expected. Fish feeding rate is increasing at 0.476 grams/fish/week.

Based on the water quality, lower tilapia populations are actually more optimal for our smaller system.

Crop Overview

All of the leafy greens are growing very well as anticipated. The LED float bed now has Asian leafy greens and the fluorescent float bed will be harvested completely on 7/05. From this point forward staggered production will be utilized to produce leafy greens and lettuce in the float beds. This will maintain a steady nutrient uptake.

In the following images you can see the change in crop size that has occurred over the last two weeks in the media bed.

 plant comparison 1.jpgplant comparison 2.jpg

The crops have been growing better than anticipated and even our tomatoes have recovered fully and are showing good growth. There is some leaf curling due to high heat loads in the warehouse which can’t be helped. The zucchini squash, cantaloupe and cucumbers are all producing first small fruits.

LED Testing Trial

The LED and fluorescent trial results are in and listed at the top. Exactly as expected the LEDs produce at slightly faster rates. There was no significant difference in taste between the two grow methods although further testing will need to be done to determine the nutrient content of the tissue itself to see if a difference exists. With the LEDs producing stronger pigmentation it is likely crops grown under it will contain higher levels of various nutrients.  

LED Collared.jpg

You can see the remaining collards in the Flourescent Float bed below. 

 Float bed 1.jpgFloat bed 2.jpg

Staggered production has already begun in the LED float bed and the same will be done in the other when the collards are harvest very soon.  

Topics: Aquaponics, Aqueduct Development, Niles, LED