I am new to farming and mostly looking to reduce the grocery bill. My 3-month old indoor aquaponics system is experiencing a very odd issue: the plant growth is uneven - see photos attached. Most plants sprouted from seeds and quickly grew to baby size but then just stopped growing, with an exception of plants on the bottom right of the grow bed. I have Kang Kong (bottom left), spring onion (bottom middle), chinese broccoli (top right) and spinach (top left and bottom right). The top left spinach plant in the picture was originally planted on the bottom right corner, then transplanted to where it is now, the growth stops the day it was transplanted.
I looked up causes of growth stunt and the most common problem is iron deficiency. I went out and bought some EDDHA Chelated Iron. Added to the tank as per instruction (my fish tank now has a slight pink tint). The system has been running for about a week but I see zero changes.
The water-in pipe is clear plastic and I notice heavy algae growth where it is exposed to light. I went ahead and cover some of these sections with black tape. I suspected the algae is consuming all of the nutrients but how come a section of the grow bed is still fine, shouldn't nutrients in the water be distributed evenly?
What else could I be missing? I a bit hesitant to buy more test kits as I have already well blown through my budget. I am mildly frustrated with the system after so much effort and money spent so any help is much appreciated!
Fish tank:
- 100 litre
- Not heated
- Ph: 7.4
- Ammonia: 0.25ppm
- Nitrite: 0
- Nitrate: 5
Fish
- 5 comet goldfishes
- Feed: a pinch of Hiraki goldfish food, 2 times/day
Grow bed
- 73 litre
- L740 x W465 x H280mm
- Media: cheap eBay hydroton with thin layer of pebble on top (the cheap hydroton refuses to sink so I have to add something heavy on top)
- Water level is about 3cm below top of grow media
Lighting
- Migro 100
- Full spectrum
- Full power 12h/day
Other
- Average indoor temp: 15 degree C with about 5 degree fluctuation
- The grow bed water-in pipe is tucked into the grow media to reduce water splashing noise
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