Measure to Manage-Aquaponics Nutrient Analysis Report #2

It’s been a couple months since I posted the last grouping of nutrient analysis reports. Things are fairly stable as you can see.

NO3 NO2 P K Ca Mg SO4 PO4 Alkty Na Fe NH3 EC pH Temp
7/20/15

25

4

21

90

60

90

120

53

135

200

2.4

0.93

1.92

7.38

72.5

7/27/15

23.2

3

14.9

110

80

100

130

45.6

145

200

1.94

0.95

2.19

7.5

72.7

8/12/15

27.5

2

20.8

90

50

110

120

60

140

200

1.71

0.95

2.34

7.34

73

9/4/15

36.9

8

27

45

50

140

100

62

135

190

1.48

0.98

2.45

7.27

70.6

9/16/15

30.6

2

35.5

35

50

120

110

101

160

240

1.32

1.38

2.56

7.13

69.3

9/30/15

33.4

4

35

35

70

115

120

105

145

230

1.19

1.28

2.57

7.19

68.1

10/16/15

29.7

2

31.5

60

60

105

110

96.5

135

240

1.01

1.25

2.54

7.05

71.9

I’ve been using well water and the sodium is through the roof at 240ppm. I’ll be interested to see how the rains will affect our well and the sodium content. In the spring, the sodium was at 180ppm out of the tap and now it’s all the way up to 240ppm. I’m still amazed at how things are growing pretty well.

You can see that phosphorus went up. That’s because I needed to use phosphoric acid to try and lower the pH. It’s a wrestling match I’m not going to win. I’m just holding out for some rainwater to cut the alkalinity down. Alkalinity refers to the water’s ability to resist a change in pH. Since my pH is a little high and the alkalinity is medium high, I’m chasing my tail trying to keep the pH near 7 using well water at 8.5.

You’ll notice potassium dropping. Interestingly enough, I was using potassium bicarbonate to actually add alkalinity when I had more rainwater available. I was hesitant to use the well water because of the sodium levels and how the system was reading 180ppm at the time. I figured adding potassium bicarbonate would give me the alkalinity and a potassium boost. Thank goodness for the photometer because as you may recall from my last nutrient analysis report, the potassium was climbing to ridiculously high levels due to my additions. I’ve learned my lesson there and will now use a combination of well water and the rainwater I’ll be collecting soon with the rainy season approaching. Hopefully, the rainwater can get my sodium levels down some without diluting the micronutrients in the system too much.

The iron levels are dropping at a normal rate. I will add a little more iron in the next week or so. In aquaponics, you usually want about 2ppm of iron.

Everything else looks pretty good. It’s funny how well stuff grows at only 30ppm of nitrate. In hydroponics, you look for nitrate to be around 200-250ppm.

I’ll keep doing the tests every other week or so and will post again in a couple months with more nutrient analysis.

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