Stuppy Aquaponics Blog

System Update: Niles 5/31/17

Posted by Conor Quinlan on May 31, 2017 2:10:24 PM

Niles

 

Nitrogen (mg/L)

 

 

 

Date

pH

Total Ammonia

Ammonia

Nitrite

Nitrate

Temp (Fo)

Alkalinity

mg/L

EC (mS)

05/08

7.05

0.25

n/a

2-5

10

78.4

35

0.82

05/10

7.15

0.5

n/a

2-5

15

76

-

0.80

5/12

7.00

0.25

n/a

5

20

74.5

25-30

0.80

5/15

6.4 -> 6.9

0.25

n/a

>5

20

76.1

-

0.81

5/17

6.9

0.25

n/a

>5

30-40

78

-

0.84

5/19

6.9

0.25

n/a

5

40-80

82

35

0.93

5/22

6.8

0.25

n/a

2-5

>80

75

-

0.90

5/24

6.6->7.3

0.25

n/a

2-5

115

75

-

1.00

5/26

7.0

0.25

n/a

2-3

150

76

47

1.06

05/12/17 -> 05/19/17 -> 5/26/17 : Total Hardness: 240 -> 290 -> 330 mg/L CaCO3 equ
Calcium Level: 52 -> 50 -> 53.5 mg/L Magnesium level: ~26.8 -> 40.2 -> 47.8 mg/L
P (PO4-) = 2 -> 3 mg/L

Niles_5_31_1.jpg

Above is an image of system #2 full of fresh seedlings. The expansion float bed on the far right will be testing the LED fixtures and will be compared directly to the other float bed which will utilize the standard 650W florescent lights. Both will grow a variety of collards and mixed lettuce varieties. The harvest quality and amount will then be compared.

 

Water Quality Overview: Since adding the water heater the nitrate levels have continued to rise but only more recently have begun to spike. Within the last 10 day the nitrate level has increased from about 20 mg/L to 150 mg/L. So overall the transformation process has very distinct peaks where rapid conversions from ammonia to nitrite and nitrite to nitrate occur within a few day period or less after an extended period of bacteria growth between each nitrification phase. The drop in ph has been far more dramatic in the last few weeks and even the addition of 200 g of MgCO3 on 5/15 only brought the pH up from 6.4 -> 6.9 and only maintained an adequate pH for 9 days. This is due to the larger water holding capacity of the system with the expansion float bed attached. A larger addition was therefore necessary on 5/24 to compensate for the extra water held by the expansion float bed (about 300 extra gallons). 100 g of K2CO3 was added with 200 grams MgCO3 to help increase the buffer/pH to higher levels while also adding the limited nutrient K for the newly seeded crops. This had a more significant impact on pH which increased from 6.6 -> 7.3.

 40 g of the new micro nutrient mix was used to added mainly Mo, Mn and Fe but adds all vital micro nutrients. Thus far no negative effects have been experienced due to the addition as expected. It is important that a micro mix like this NOT be over used as it can become toxic to plants if excessive micro nutrients are dissolved in the solution, generally a MAX of 1 mg/L of any micro nutrient, other than Fe which is required at 3-5 mg/L, is more than enough, nutrients like Cu and Mo will cause toxicity problems at levels around 0.5 mg/L or greater.

 Our Micro Mix is called: JR Peters M.O.S.T Mix, contact JR Peters Laboratory for product.

 

Fish Overview: These blue tilapias are doing far better than the locally sourced tilapia in system #1 particularly at their current size. They are consuming slightly more feed than system #1 at 233 g/day. On 5/23 the tilapia were weighed to determine the current feeding percentage which was approximately 3.3-3.6% of their body weight (avg. of 72.85 g/fish). This is the same or slightly greater than the rate approximated by our fish size to feeding relationship graph below. This is far greater than the feeding rate of the juveniles in system #1 which consistently consumed <2.5% of their body weight during a lot of that earlier growing stage. Even since the weighing the feeding rate has been increased further to 260 g/day on 5/26.

Niles_5_31_2.jpg

Crop Overview: During this early stage of the system cycle most of the system will be dedicated to growing mixed collards and lettuce in order to do the LED and florescent comparison described below. 

The media bed has been seeded with sage and lavender as well as individual squash, tomato and pepper crops. The nutrient content of system #2 is increasing so quickly, due to the high quality of the fish, that immediate filling of the systems with heavy feeding crops is required. 

 Niles_5_31_5.jpg

 

LED Testing Trial: The LEDs and Florescent lights have been put into place above the grow tanks and will be used to compare results between the two lights. The LEDs consume approximately 40% less energy per light while outputting a higher quality PAR output. Therefore, we expect these LEDs to produce larger and higher quality produce over time. A variety of collard and lettuce varieties from the same seed stock were used in each float bed for a direct comparison. Both float beds were filled with the seedling on 5/22 and will be grown in a batched fashion in order to provide more accurate visual data.  Everything for this test was seeded at the same time, in the same grow tray, with the same seedling nutrient solution.

Lighting Set-up: The LED lights have been placed 3’ above the crops to ensure proper light uniformity with their smaller footprint (size) while the fluorescents have been placed 2’ above the crops. The LEDs produce an average PAR between 300-330 umol/m2/s with the very lowest reading being 250 umols/m2/s at the farthest edge of the grow tank. The fluorescents produce an average of 280 umols/m2/s with the lowest reading being 240 umols/m2/sec at the farthest edge.

 The LED provide slightly less uniformity due to their smaller footprint but the fluorescents produce significantly more heat directed towards the crops than the LEDs. Clip fans will need to be used to help reduce the heat buildup and improve transpiration of the crops in that area.

 Mixed lettuce, which was added to one raft on 5/16 to ensure the water had enough nutrients, is already producing significantly more pigmentation and compactness compared to the lettuce grown in system #1 under the fluorescents.

 Updates on the comparison, as well as pictures, will be provided continuously over time. Below is an image of the LED light up close:

 Niles_5_31_6.jpg

 

 

 

Topics: Aquaponics, Aqueduct Development, Niles