Backyard Aquaponics
A place to discuss aquaponics

My then 3 year old girl cut thru the power cord of the vacuum cleaner with scissors while it was plugged in and on at the switch. Needless to say, she got a hell of a fright. The safety switch saved her life.

Back on track... ...what is the best ratio of ft to gb size, I have read all about the 1.2 ratio, but wouldn't unused capacity dilute the nutrient (fishpoo) concentration? What I am trying to ask is if I put in a say 2000L ft to allow for future expansion of the system but only stock it for say 500L of gb isnt the nutrient too dilute for optimum growth? or is the best approach to add additional ft volume as you go and concentrate on the nitrate/nitrite/ammonia readings? Is there is another thread that has already answered this? Don't want for you guys to rehash what has already been said

Snag, the ratio is 2:1 ... growbed:fish tank...

i.e ... to stock to near capacity rates you would need to have twice the growbed capacity as your tank volume...

In your case with a 2000ltr tank you'd need 4000ltrs of growbed capacity if you were going to stock fish at say 5-6kg/100ltr....

Most people stock at around 3kg/100ltrs.... with a "mature" system people have been able to get away with a 1:1 ratio....

But that requires a system that's matured over a period of time and a "maturing" of your own "managerial" experience to match it.

Others may suggest slighty higher stocking figures, but I'm sure noone will suggest less than 2000ltrs of growbed....

OK, so ft volume s determined by my ability to fund/build/fit in gb tanks at 2.1 ratio and I would be better served by adding/building another system if I want to expand later? Just need to nail this down first as other things also affect my design, like need to add a carport etc and I need to have maximised my ap potential for the future, not build myself into a corner.

If you look at it from the fish point of view:
The amount of fish you can stock in your fish tank is mostly dependent on the volume of growbed media that supports the bacteria, and the plants in it that use up nitrates.
100L of planted growbed (with the optimum depth of 30cm) can support a maximum of about 3kgs of fish. Those 3kgs of fish need at least 50L of fish tank volume (because of the 2:1 ratio).
Unless you make your fish tank a million liters, it doesn't really matter all that much that your nitrates/nitrites/ammonia are diluted when compared to a system with a 2:1 ratio; it just takes a little longer to cycle your system.

So if you want to be able to expand in the future, get a fish tank as big as possible. Not only can you hook up more growbeds to it later, it is also better for the stability of your system, as you will get less fluctuations of pH and NH3 for instance.

2000L of fish tank with only 500L of growbed sounds fine to me. Actually, my own system has a 2000L tank with 700L of growbed.

You could support a maximum of 15kgs of fish if you have 500L of growbed volume (though I really wouldn't stock that high unless it were a mature system).

Has anyone investigated plastic stock troughs for growbeds? Toowoomba supplies a huge agricultural area and all sorts of things are available here. I'm wondering about food grade plastics. I know there has been discussion regarding DWV and Pressure piping and the leeching of nasties.

Here in the US, a lot of us use Rubbermaid stock tanks. My system has 3 50gal stock tanks like you would use for watering sheep or goats, I suppose, plus one 150gal stock tank that might be used more for cows or horses.

My SIL got one to try out, very sturdy but not cheep.
Need to cover inlet into the float chamber but shouldn't be problem.

Got no details, didn't see them some tree months.

SNAG, Nylex have a range of "longline" feeder troughs.... I've got one I'm setting up for some tomatoes... cost me $120 on eBay, normally they're listed for about $250....

http://cgi.ebay.com.au/FEED-TROUGH-2-4m ... dZViewItem


Nylex used to have them at that price but have jacked the price to double...

http://www.nylexwater.com.au/products.p ... ategory=14

And a 4,500ltr "Cattle" trough that sells for about $900

http://www.nylexwater.com.au/products.p ... ategory=18

http://203.63.31.254/~nwater/uploads/br ... 7.1.07.pdf

But I see that know they're offering a complete range of "aquaculture" products....

http://www.nylexwater.com.au/products.php?category=22

Click on their "zone" map selector for your closest supplier....

Thanks Rupert
The Nylex Aquaculture 1000L tank for $746 looks ok for what I had in mind but I also like the Duraplas aquaculture tanks...need to ring the local deraler and get a quote. I am dropping in on Aussieponic this weekend so I'll check his gear out again.

I checked with Duraplas a few months back. Delivery was about 5 months after order at that point . Regarding the nylex, the 2000 litre looks to be better value (in fact, I don't think I saw a 1000litre).

BTW - looks like the nylex bases are not included in the cost and they are very very expensive. Like nearly as much as the tank itself. On that basis the duraplas look to be better value.

Yeah, I wouldn't be buying the bases.... but then again most other tanks being supplied don't come with bases either... except maybe the duraplas.

On the way back from Brisvegas today I bought the November issue of Silicon Chip. It has a very interesting design for a "PIC based Water Tank Level Meter" which also has an add on telemetry unit for monitoring up to 10 tanks plus remotely controlling pumps. I have to admit that I am a technohead and have spent thousands of hours with soldering iron in hand making things of dubious reliability, but this looks taylor-made for control, or at least monitoring, of ap systems. I know, I know, it doesn't fit in with the low-tech (electronics-wise) approach of many. Thats ok. In fact, ap should be based on low-maintenance systems. I just thought that this unit could be very useful for those who want greater control. (Today, the fishtank!!! Tomorrow, ....muahahaha!) What do others think?

any chance of scanning the atricle?