Backyard Aquaponics
A place to discuss aquaponics

good morning all.

have been lurking on the forums for awhile, soaking up info and envying a lot of your systems since i can't currently set one up. Have a nice inorganic hydroponic garden on the patio of my apartment, but have to wait until this coming summer/fall to start my first AP setup, once I'm settled in to whatever house my wife and I end up buying. anxiously awaiting that, though. for now, the hydro garden will have to hold me over. :-)

anyway, i was looking through stocking density questions, and a question occurred to me. if fish are grown from fingerling size and harvested at full size, then replaced with fingerlings to start over... how do we supply enough nutrients consistently to the plants to keep them going strong? I would imagine that the nutrient levels would drop off when we harvest the larger sized fish and replace them with fingerlings.

so, am i worrying about nothing? or do we see large nutrient dropoffs when we do this and/or supplement in any way to keep the plants going strong?

Yep you do see nutrient drop offs in Immature systems, can be over come by adding seasol or worm juice, mature (over 1.5 -2 yes old) systems don't generally have this problem as there is lots of built up goodies in the water

Not sure about over that part of the world... but typically in Perth Western Australia, for those keeping trout and barramundi, when the fishes are changed out, it is also usually when the veges are changed out... change from summer/winter and then back again... so the nutrient uptake also tends to drop when the previous seasons plants are removed and replaced with new seedlings...

For those keeping Silver Perches, then they would generally not require a whole batch harvest that would impact nutrient level...

People tend to think that fingerlings don't produce the same amount of waste as adult fish...

It's not necessarily true... think of them as teenage kids.... they tear around like crazy, eat and shit... and produce other wastes...

Typically they consume more food vs body weight.... more often....

The difference is often neligible..... and the plants are constantly supplied with nutrients each flood cycle anyway...

Welcome to the Forum.
While your waiting check on your water supply to find out about the Chlorine or Chloramine addition in your area. Don't wait and get surprised.
What kind of setup are you thinking about building?

Man - what I would not do to rewind the clock 15 years before we bought our house. If I knew about AP and the things I do now, my location would have been very different. I see nothing wrong with choosing a house based on AP utility...

Good luck!

The best solution is to have 2 fish tanks(even if the 2nd is a 44gallon barrel), more if possible that way you can have fingerlings in whilst the others are growing out ..... It really depends on the fish you are going to want if they will eat their own or not.... I have 3" jade perch in with my 10" jades and the only difference is the feed i throw in, the little ones eat the small pellet (big ones dont eat it as too much effort)

#The other option is to keep 1 tank(44gallon cheap/easy) full of feeder fish (live breeders platys & mollys) that way they will keep the balance without too much fluctuation.... and if your fish are meat eaters you have a good supply of them for treats....

I sometimes dont think about these sorts of problems as I have a really large system(30,000 ltrs) with multiple fish tanks which makes things very stable ie PH temp etc my only problem is the month it gets too cold for the fish to eat but some pipe on the container roof will fix that...and an old bustard arse hot water system not plugged in.....

If you cycle up fishless and then start off with a nice appropriate number of fish and grow them out to plate size and then remove all fish from the system. (providing we are talking about a media based system where solids are left in for mineralization over time) There is a good chance you will see the Nitrate levels drop significantly if you have a period of time with no fish but I will also say there is a good chance you will still have enough nutrients being slowly provided by the solids slowly breaking down in the system that it won't be as big a problem as one might think. Think of the solids slowly breaking down in the media based systems as "slow release fertilizer" or a "nutrient buffer".

I've had systems that I've left fishless for periods of time and the nutrient level drops but usually not quite to 0 and the plants keep growing. I will often dose the system with an ammonia source and check to make sure the ammonia and nitrite levels still drop to 0 within 24 hours before I get new fish to stock just to make sure I haven't starved my bio-filter to death. Which starving the bio-filter is the biggest danger of leaving a system fishless for a time between batches. I find it interesting though that I've been able to leave a system fishless for a few weeks with no dosing and then I can dose up to 4 ppm of ammonia and find it back down to 0 the next day on a mature bio-filter like my 300 gallon system. I should probably give that system some fish again soon though.

Don't over think it too much, ya kinda have to monitor aquaponics closely but you have to resist the urge to tweek it too much, let it do it's thing and have patience.

well said TC I find I spend most of my time at our system very very relaxed listeing to the water trickle, gurgle, splash, and watching the plants literally grow infrontof your eyes... in summer when full growth in session the plants have all the nutrients and water they need... I have a skeptical brother in law that said it(aquaponics) wont work for me ....they will be visiting in another month so then i am hoping to hear wholley crap from his mouth when he SEEs it working.... All we can offer you are suggestions - every system is different beacause of the factors that go into them ...ie different water supplys, different media, prefiltering but yes TCis right when saying Just go with the flow the system will work itsself out as in nature...

Happy Aquaponicing

We harvested our Baramundi from the system about 6 weeks ago and the system has been empty since then, with nothing added. Growth in all plants has continued and now we have small trout that went in last Friday. The trout will be fed many times a day, although they won't get the feed quantity the barramundi used to get so I imagine that plant growth will slow a little, but it's never really noticeable to any great extent.

Have just started a new system with Barramundie fry, I have been told that rain water is no good because of the PH and I should add mains water to the system. I'm in an area where there is no mains water and all water is captured from rain fall and collected from roof area and stored in tanks.
What is the correct proceedure to use????

Use the rain water.... don't know who told you otherwise...

You have Barra fry? How big are they? You might be needing some heating over winter if they are only small..