Backyard Aquaponics
A place to discuss aquaponics

Hi simo, I did see somewhere (not sure if here) think it was system in US where they had like a big fish net lowered on the bottom, pulled the top section up (which raised the sides) then pulled the bottom section up which bought all the fish to the surface. Will watch with interest as I have a 5000 gallon poly tank (only used for garden water) which could grow out some nice barra.

Actually my thought was to combine both ideas, 4 wedge shaped nets which divide the tank in quarters but can be independently raised for catching or inspecting the fish.

Don't watch too close chainsaw I still have to find the est $5,000 (and thats using gravel not expanded clay) and have it approved by the boss, probably looking at 5 years as I want to intall solar power first.

The net idea may work but I have bird netting over my trout and we loosened it off and sank it to catch trout the other day, they get hooked up in it quite easily and some are hard to get off, just like gill netting I suppose, some something else to think about, $5k is a good estimate for AP, plus another $15-20K for solar power Me personally reckon's if you do the maths on what solar costs and the life span and replacement costs of battery's then you would never end up in front, Dr Karl from TV would back this up (and has, although he still has, mainly as he say's "because He Can")

But if I don't get solar how am I going to run my AP pumps when the food wars breakout, society crumbles and no one is left alive to run the power plants?

Simo, have you been eating to many Mung Beans sure isn't happening down this way anyhow, but have friends in Morawa went solar a few years ago, they had eaten 2 many mung beans they would have never recouped there set up costs and the $10,000+ to replace the battery's every 8 years or so didn't add up either, it was the mid 90's when they changed, they also had most appliances on 32v and had to run a extension cord to parents house next door so the kids could use the play station, no doubt things have changed a bit by now but when I looked into a couple of years ago things still didn't quite add up, if things get that bad in bullsbrook contact synampto man in South Africa he will design a treadle pump and supply a tribe to peddle it for you at a cheaper rate
My opinion anyhow, build your AP first and then save for Solar, you will get a better return from AP

Thats true, but with the REC the gov is giving I can get a grid connected (no batteries) 2kw solar which is guaranteed to still work 85% as when it was new in 25 years time and it will cost $7500.

My 1kw system only cost $2k after grants and pay back only a couple of years at that price (I got the even better grant that existed last year). Unfortunately all my pumps, waterfalls, pond filters etc seem to be using most of that free power (slight exageration maybe).

As for the system design, if you get some more good answers for the ratios pls let me know, I am running my 20,000 litres with only 1,000 litres of grow beds and 30 odd fish. Growth started off slow (been going 6 months), but seems to be starting to really kick along now with basil, strawberries, garlic, sliverbeet, lettuce, cucumbers, chillies, tomatoes, capsicums all growing well.

I use 30min on 30min off to try ang get more water turnover, but the 'dilution' doesn't seem to be an issue if growth is now starting to kick along?

Dilution should not be an issue. I don't care if you have two goldfish in 100,000 liters: it will take a long time to build up nutrients (maybe toss in some urea for fishless cycling?), but if the plants balance the fish then the nutrient levels should be ok. The big difference between lightly stocked and heavily stocked systems is resiliency: a lightly stocked system has slower and smaller temperature and chemical fluctuations.

Simo you posted on Nocky's thread, your worry about over stocking with SP. Your GB may be your limiting factor but from my experience don't worry until the SP actually get bigger, they do take time!! Keep a check on your nutrients as they grow and either change a bit of water on a regular basis (like aquaculture) or simply eat a few. I have about 150 SP in my system (3000 + 800L) and until they get bigger than my hand, I'm not worrying.

A word of caution.... as I keep saying.... size doesn't matter....

Don't be misled, or lulled into a false sense of confidence... by the size of your fingerlings...

Small fingerlings are fed a higher protein feed... and/or significantly more times/day... at a higher %/biomass...

In warmer waters, with increased metabolism.... producing more ammonia than you might think...

The warmer water has less oxygen carrying capacity, the increased metabolism of the fish requires more oxygen, as does the bacterial conversion of both feed and wastes...

It is a trap fro unwary beginners.... to assume that overstocking a tank, on the basis of fingerling "size"... allows for a sense of complacency...

Yep, thanks for the word of advise Rupe. The fingerling SP are cleaning up a reasonable amount of feed and that being high protein, left over trout pellets, crushed.