Backyard Aquaponics
A place to discuss aquaponics

I think the system has a pretty serious phosphate deficiency. The young plants are turning purple and it's been pretty heavily loaded with flowering plants. Ie. Tomatoes, broccoli and let some pak choy got to flower. I watched bright agrotechs video and he used a rock phosphate but I am having trouble tracking it down in Newcastle, (Australia). I looked at other phosphates at bunnings but didn't get them as I wasn't sure. Seems they were made of guam... Not sure if adding bird sh1t is the way to go. I can add pics later if people want to see them. We have 20 silver perch, 9 yabbies and 8 goldies. About 1200 of water including sumps and about the same in growbeds.

Think rock phosphate comes from birt/bat shit, though may be well aged. I was upping my phosphates with phosphoric acid when I had high ph issues. Now using organic rock phosphate, lightly sprinkled. around flowering plants.

I would not want to use non aged bird/bat shit - have you tried an organic gardening supplies place i.e. NOT bunnings/masters etc. How old is your system?

System is about 6 months old. First attempt at ap. And our first lot of crops. Getting alot of trouble with germination at.the moment. At the start we could chuck any seed in and it would erupt. Now they are springing up and dieing off and lettuces don't seem to be growing while tomatoes pak choy and broccoli are going well.

I have just uploaded these images:


Kale which has how been in for 9 weeks. It has just stopped.

I have just uploaded these images:

Sorry about the size did it on my phone with an app. Didn't even consider the need to resize

How's the pH,? Have you got a phosphate test kit, or can you borrow one? I suggest adding some seasol, removing some of the fruiting plants, and upping feed if possible.

In a young system that's had lots of fruiting plants it's likely that you may be low on potassium too. You may have not built a sufficient and accessible nutrient bank yet.

Could you post a couple of pictures from further back? Thanks.

PH is about 7.5. It has been steady for a while. I add seasol around once a week. But it's the normal seaweed extract which I think is low in NPK from memory.

I have just uploaded these images:


Again sorry can't work out the resize with the phone

I was having a tough time telling whether this was new or old growth turning color. Looks like it's old growth so probably a mobile nutrient deficiency.

Mobile Nutrients - Deficiencies show on old growth first
Nitrogen, Phosphorus, Potassium, Molybdenum, Magnesium and Zinc

I can't tell for sure what is going on - Could be Nitrogen, Potassium or Phosphorus or a combination of the three... I'm going to suggest the shotgun approach - try adding blood and bone meal along with some seasol to get all three of these. Adding one (if we guess wrong) might just make things worse because of competition for binding sites.

Hope this helps.

Got blood and bone. Sprinkled a bit on. How much should I be looking at adding?

Probably between 10 and 50 gm/cubic meter of media but I'd err toward the low end until your sure your system can handle it. I think it's safe to go higher than this based on Gordon's (Gunagulla's) experience, whether your system needs it . Sprinkle it across the grow beds like you've done.

There's a couple of threads where Blood and Bone is mentioned if you search. One is Gunagulla's and then Gabe also uses this. I think it's a good idea and seems to be working so I've been pushing it along a bit but it is new and you could have troubles with ammonia because of the proteins releasing nitrogen compounds (Hasn't been an issue yet for anyone though).

Hope this helps.

Thanks for the help. Hopefully it bounces back nice and quick.

Sorry just one more quick question, how long should it be until I see the plants improve. Will they lose the purple colour or are they gone and should they be removed?