My farm is 4 months in...fish are happy and not dying! water is clear and has a great PH once i added in the pieces of coral...plants are slowly growing too, but it is obvious i am lacking micro nutrients....i have 2500 gallons of water combined with 4 16x3 (1 foot deep) grow beds, and only about 50/60 small fish...im almost positive i need more fish, these plants are struggling for fertilizer, my main question though is...does tilapia effluent have all the essential nutrients my plants will need if i get enough fish in there, or do i always have to be supplementing extra nutrients? Im learning this science so that i can duplicate it in poor regions around the world, mainly place where it may be difficult to come across a bottle of seaweed extract :)
Im fine with the plants just working as biofilters, because fish is my primary crop...but i'd be nice to have some healthy veggies out in the bush of Africa! Thanks guys - i really appreciate your help...great to be a part of this community!
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It will all depend on what you feed the fish! Don't expect a cheap pond feed or aquarium feed to provide ample/complete nutrients for recirculating culture where you are trying to grow out lots of fish, big, fast. Also don't expect such feeds to provide lots of nutrients for the veggies. High quality fish feeds designed for recirculating culture are far more complete than something designed to throw out in a farm pond or any earthen pond since in natural ponds the fish get a fair bit of natural food and the pond feed is just to help grow them a little bigger/faster than they would otherwise without any supplemental feed (it's just to "fatten them up so to speak".)
High quality complete feed will be far better at providing the complete nutrients for the plants if you have it all in balance but new systems still often need a little boost of seaweed extract (if not adjusting pH with potassium hydroxide or potassium bicarbonate alternating with calcium hydroxide or calcium carbonate, regular additions of some form of potassium will likely continue to be needed occasionally since potassium is often a limiting factor in aquaponics.) Depending on media, pH and source water iron is often lacking or locked out as well so may need supplementation especially if pH is high.
Now if you are not particularly interested in growing veggies you may be able to get much filtration from something like duckweed and it may also provide a supplement to the fish feed while doing a good deal of filtering/ammonia uptake but this will probably be a bit more like aquaculture and green water culture than what we think of as Aquaponics.
Does this help?
Hey I have been wondering the same thing. I am using a cheap fish food for pond fish but none of my plants were producing any fruit. I happened to find a seaweed extract fertilizer which i poured into my grow bed and now the plants are producing fruit. Once the seaweed extract cycled through and into the fish tank the water turned completely black but the fish were fine. The water eventually cleared up but not to the original transparency, it's still murky. So if you don't mind murky/ greenish water I'd recommend adding a bit of seaweed extract to give your plants that added boost.
Hope it works for you.
In a mature aquaponics system the water will normally have a tint somewhere between slightly yellow to tea or coffee colored. It should still be transparent enough to see the fish and murky or cloudy water isn't a good thing but tinted water is normal in a healthy aquaponics system.
The potassium supplied by the seaweed extract is often needed in a new aquaponics system.