Backyard Aquaponics
A place to discuss aquaponics

Hi All, I recently read an artile on Aquaponics and am keen to have a go at it, in place of my standard vegie garden. I have a bit of stuff around that I could use and am looking for idea's as to system size I should start with. I currently have 3 old baths with access to another 3 that I thought I could use as grow beds. What size fish tank is best?, I am looking at possibly 1000L Tank. Would this be suitable or 2 big? I look forward to your comments.

Welcome Silvertrees
It is difficult to achieve 'too big'. You just need to alter the formulas to suit.

in order to maximise the use of your tank, you should have 1 to 2 times the volume of growbeds.
so if you have 6 baths, your tank should be equivalent to 3-6 baths in volume.

However if you have a 1000L tank, this means you can have between 1000L and 2000L of growbeds.

So work out what you can fit.
Then work out what is the 'limiting factor' ie your smallest resource.

if you have 500L of growbed and 1000L of fish tank, then your growbeds are the limiting factor, and we count your tank as 250-500L for fish load calculations.

However more water is good. the more water you have, the more stable the system is.
There are few hard rules in AP, so have a think, let us know how you're thinking of arranging your system, and we'll try to make sure you load your system safely. (as few fish deaths as possible)

Thanks for the reply,

I will have to buy the tank to start my system so it looks from what I have read and your reply that 1000l is a good start. I assume that can always add additional tanks if required and run them in series/parallel.

From all my reading and internet surfing I have yet to find any negitives for this system. Is at as easy it seems or am I missing something.

Running is series, is possible, but flow rates can be an issue... Hell do I know that! so many revisions... Parrallel works more reliably.
yeah you can add more, most ppl do, BYAP like a virus in that respect. Or maybe a bacteria culture.
It just grows until it reaches equilibrium with the property, and the care available to it

just try and design your system to be expandable without having too many different levels.

The only negatives to AP are that you can't grow everything in AP... but hey, we don't propose that you remove all your dirt garden (although some ppl have )

a 1000l IBC is a good start, because it's a nice size and is probably be best economy on capital outlay... eg cheapest by volume, being $0.20/l or so,
unless you want to use blue barrels as your tank, which are a bit small. they're about 15c/l

anything else is ridiculously expensive here because of the drought, water tanks are big bickies atm.

Heck, you could even temporarily use a bath as a starter fish tank if you already have them, There are people out there with a bath as a fish tank and another bath as a grow bed though that is a rather small system.

1000 l is a nice size start for a system fish tank. 6 baths are a nice start for grow beds, real nice!

Do lots of reading though before you spend much money as you might see some ideas around here that can save you some.

Good luck and welcome to the insanity

And some not so good ideas, that'll cost you plenty It's good to know about them, just so you can avoid em

Hi Silvertrees, I built a small bathtub system for my Missus, 6 gold fish, some minnows and Pygmy Perch and the famous Mussels, all is working well, have thread in new systems called My Missus's Little System, and I know member outback ozzie also started with bathtubs

A 1000 litre tank would support 2 or 3 bathtubs pretty well.

If you use a bathtub as a sump as well and go CHIFT PIST you could probably have the 1000l tank for the fish, 4 bathtubs for the vegies, and 1 for the sump. This would be a very stable system. The sump bathtub would have to be the biggest one though. Or the water will run out, unless you go cont. flow.

Flood and drain is the way to go.
Slow Flood and fast siphon loop or bell,
or timed Fast Flood and continuous slow drain.
Continuous flow systems are too finicky in my opinion. I'm worried enough at keeping my indoor tank continuous flow without it overflowing because of a blockage...

Exactly how much water does an average bath tub hold? I've always wondered. It makes math hard to do when you can't even estimate. I'd guess (due to the size of a 44 gallon drumm) that they'd hold about 200l... but really have NFI.

I've heard 200 l for a bathtub before but they come in so many sizes and shapes that it would probably be silly to use that number as a rule.

Myself, I would probably tell you that if you had 4 bathtub grow beds and were doing CHIFT PIST, you should have two bath tubs hooked together to act as sump. It seems to me that many people try to use too small of a sump and it is just never quite good.

Hopefully this won't confuse you too much.
If you do a system that is constant height in fish tank pump in sump tank. Your sump needs to be big enough to hold all the water needed to flood your grow beds plus a little extra so you don't run your pump dry.

Most people estimate that a grow bed filled with gravel will have about 60% of it's volume taken up by gravel and 40% water when flooded. To give myself a little extra margin for error I usually just say 50% 50% (it also makes the math easier.) So if for instance the bathtub is 200 l, then that bath tub needs 100 l worth of sump to catch it's water (assuming this system gets a sump.)

I like to add and extra amount of sump space just because most sump pumps can't pump all the way down to the bottom and you want a little extra volume beyond that so you don't have to top it up every single day due to evaporation/transpiration.

So my personal rule is that the sump tank should be 2/3rds to 3/4ths the sized of all the growbeds just do you don't have to worry about it overflowing or running dry all the time. That is just me trying to make things "fool proof" only to find that I've created a test for a better fool.
I often go for a sump tank of equal size to fish tank which allows or lots of grow beds but many others seem to resist this idea as being too costly or taking up too much space. The benefits are that you can almost achieve the 2:1 Grow bed to fish tank ratio with heavy stocking density stay constant height in the fish tank and have all the extra water for stability of the system. Even if you don't start out with that much grow beds, it allows for easy addition of grow beds without having to add to or upgrade the sump.

Good luck

+1
i have 3600 l ft and 3000 sump.
this is of course excluding the 2500 l some that has a hole in it
big sumps bsd the way to go. They also house mussels and crays well, as neither of these require much depth, the changing water height phases them not.

Thanks Guys,
Those comments are all great. I am no mathamatition but to my calculations a bath holds about 220l (200 litres for easy calculations). With the comments recieved I am thinking that a Flood and drain system with a 1000l tank and 1000l Sump is probably the best place to start. I have a couple of drawings of my proposed system (can't get them on hear) and there is room to expand later.

I am keen to have a look at a working system! Is there any open days or similar in the Melbourne area that I could attend?

Thanks again and I look forward to your comments.

Dunno of any planned meets any time soon Silver,
where abouts in melbourne are you, there's a few of us scattered around, some really nice systems. Most ppl are willing to welcome you for a private viewing although with XMas coming up most ppl will b hard pressed for time.

Have updated my Profile - I am in Warrandyte, understand the christmas thing (this time of year is mad) but if anyone has some spare time in the next few weeks that would be great.

My system is hardly what you'd call impressive, and I'm off to NZ for work come Jan 5, but after that if you're still looking you could come over here.
You're not really all that far.