Backyard Aquaponics
A place to discuss aquaponics

Yes and no..... if, (and it is a big IF), you are/were stocking at very high density levels then yes you need the extra capacity to process the extra fish solids and feed wastes..... automatically this would double/triple (whatever) the amount of bacteria available to process the waste....

But just as importantly it doubles the amount of growbed area available to grow vegetables.....

Necessary to remove the extra and probably exponential increase in nitrate production..... ultimately a problem and algael blommer/fish killer

An AP system is all about a very finely tuned balance and holistic synthesis.... and matures and becomes more forgiving with time.




Definitely NOT..... the flood and drain supply the necessary oxygenation of the plant roots necessary for good plant growth and health.

If you were to provide a highly oxygenated, high constant flow to you plant roots... ala floating trays like the UVI system... then possibly...

But in an already humid environment I think anything other than either flood & drain or the floating raft method of UVI would lead to even greater problems than a hydroponic environment.

Secondly the flood and drain system fulfills a critical part in the overall AP system.... the oxygenation of returning water to the fish tank....

As I said previously, UVI has taken a different approach, but the approach in itself limits the types of plants that can be grown.

Have a look at UVI's systems and some of the other systems in Haiti, El Salvador, Jamaica, trinidad etc.... you'll find them by searching "Goggle" or even better by searching member systems here......

fiar enough, nice background info TD, feel like I know you better now :-) by steady state would you mean continuous flow through the GB?
This is done, however it has it's pros and it's cons.
As rupe said, if you have 2:1, and use continuous, your fish tank will be at 20% capacity most of the time because all the water was in the GB.
Also continuous flow has troubles with 'dry spots' where the water doesn't flow because of the 'path of least resistance' theory.
the other problems are, your plants can get wet feet. To reduce this you slow the flow so the water doesn't come so high in the GB.
Because of this blockages are more likely.
A siphon is a quick suck, and will blow most obstructions from the pipe.

There are downsides too, but I'm pro flood and drain so, tend to gloss over them.

When I was referring to a steady state system - I wasn't not referring to keeping it flooded - you are correct, that would kill most plants (unless you do things exotic) - I was thinking more in the line of drip irrigation (but probably needing to move more water than that.

In other words - keep the water moving all the time, instead of some of the time. In hydroponics, fload and drain is just one of the methods. (I have some background in hydroponics)

What appeals to me to AP is that it is a holistic system - but of course, that does mean you have to balance it. There are two ways of balancing something - one is by math, another by trail and error (which is fine when you start small)

Often the trail and error works better if you have the luxury of time and don't mind a bit of error. :rolleyes: Sort of like learning to walk - trying to calculate all the possible permutations of walking is pretty difficult - but babies manage to figure it out.

I will definitely be looking at systems in the tropics for ideas - thanks.

I would recommend flood and drain for hot areas - I am having a lot of trouble with root rot in my constant flow/timer system. Next one is F&D

KudaPucat,

You are correct, the advantage to flood / drain is the amount of flow is the easy of getting complete coverage. Being down by 20% is not real - since that is kept in the system at all times - therefore you would not be down that amount - would you? I.e. if you say in a steady state system that 20% of the volume is in the beds at any given time - you would merely make sure you have 20% more water in the system - it is not missing from the tank - right?

Besides - perhaps I am missing something - how do you keep from leaving the fish gasping for water if the need of water for the beds is 2 times the need of the fish? If you have to fill up the beds, doesn't it mean the fish are flopping?

Water needs of the beds is not 2 X - The bed Volume is, most is taken up by the media.

That I can believe - we aren't really hot - just about perfect weather year round - but there is no time we don't have moisture it seems. We do build shelter over our greenhouses (we have them for tree seedlings) but they are to reduce the amount of rain as well as cut the amount of sun.

Ah, there is the missing datum! I knew something was missing since obviously you all are doing it. So - the idea is to balance 1:2, fish tank to growing beds where the growing beds include media.

Yep

You could add water, but if your pump stopped, you would get overflow.
if you made your grow beds and tanks all equal heights, flow would be difficult. I quote 20% because a GB uses approx 40% volume Water 60%volume media. hence if 2:1 is used, 80% fish water will be required in growbeds. leaving only 20% in the tank.

So, to sort it out, if I were to assume a modest density of 3 kilos per 100 liters with a growth rate of 6 months to edible (true here) - 1,000 liter tank might be adequate - this would mean double that for the beds - but filled with media.

It would make sense to phase this in as well - I notice that for the first month or so, you can not assume the system is truly working yet - so you need to watch your ammonia levels, etc. I suspect it won't be hard to get bacteria going in the tropics.

If we were to go with a 55 gallon barrel has 200 liters (it is a bit more) - then we are talking a 5 barrel system - just to get the visual. I will probably go with something more permanent like concrete pools - since we don't have freezing and thawing cycles - these are rather easy and pretty cheap to build - and I don't think I mentioned I have a full time construction crew.

Since part of the issue appears to be getting acid levels too high - having concrete holding tanks might actually be a minor plus (though I would paint them).

But, I have lots of work ahead of me reviewing your designs that you have posted now that I know scope of project. And a lot of reading about it too. I will almost certainly start with something small - about a 1/5th of the eventual size - no reason to have feast and famine when it comes to fish so the fish need to be phased and rotated like someone suggested.

Thanks for all the help.

IMHO - at a 2:1 ratio there are many, many times more bacteria holding media than would be absolutely required for effective biological filtration, particularly if a media with large surface are is used. However as has been said - the media plays many other roles including solids filter and plant stabiliser.

I'm factoring in a sump tank into my design of a minimum 25% of fish tank capacity.... but not including the volume in any of the other calcs...

If we were going to be pedantic, we'd have to work out the volume capacity of the plumbing, both supply and return..... I figure this is roughly equal to the sump provision for the sake of simplicity

That is cured with a float checkvalue - which would be nice with an alarm on it to notify that you had a failure. Overflow as long as you have netting isn't a crisis (to keep from washing the fish way) I would assume - I would need netting anyway to keep the birds out.

So, to leave only 20% of the water in a tank does not stress the fish? I could see with some species it wouldn't - but I suspect trout for example would roll over and die - but I could be wrong, just working from theory.

water is a critical and limited resource where we live. Major Drought.
I have noticed that float valves SEVERELY limit the flow in these systems.