Rich's first system

[Rich]

My aquaponics system consists of 500L tank, 2x160L growbeds with a 3750L/hr pump. The system works on a constant flow, flood and drain controlled with loop autosiphons. The cycle floods in 20mins and drains in 5 mins. Excess water is diverted back into tank, helping with aeration. The plan once it has cycled is to put 30 100mm barra fingerlings in from the Barra Farm down the road. The cycling is taking some time as I over did it with urea (200-300g was too much) and still have very high ammonia levels. The system is located under a shade cloth area facing west. We have just planted: Cos lettuce, dwarf beans, cherry toms, zucchini and Bok Choi and will see what survives. Growbeds are supported by 44gal drums with plenty of room to expand down the track if the plastic containers prove hardy enough.

[Murray]

Good one Rich, simple and effective.

[julieleanne]

HI Rich,

looks good... nice and simple.

the grow beds... are they the plastic bins you can buy from Bunnings for about $35 each? i ask only because i baought a couple with the same idea of using them as extra beds when i need them but could find no details of the plastic grade and was then a little worried abut using them to grow my vegies just in case.

cheers Julie :)

[GreenCow]

Hi Rich....welcome. Never seen a loop autosiphon. How is it set up?

[Rich]

Hi JulieLeanne, Yes the G'beds were from B. However, I don't know about the plastic used in there manufacture. Also with the weight of the gravel they are bowing out (Hence to ratchet straps around them (not very effective)) I also don't Know about UV stability. Down the track I will probably upgrade to Fibreglass GB.

[Jason Palenske]

The general rule I have learned for UV stability is the darker the better. That's why white is used inside, but the time it takes is negligible. More often extremes of cold and heat will do in the plastic before the sun will. Very nice set up Rich, looks like it will be easy to expand as you go. Keep up the good work.

[Rich]

An update on my system and a few questions.
The 30+ barra are going great. Feeding really well. Since introducting the barra, I've lost 4 (unsure of the cause of their deaths as the system has been stable). They are growing fast at a rate of 1.25cm per week (going on measurement of the dead fish). Now they are around 14-15cm The pak choi and lettuce are growing well, the zuchini plants are massive but the fruit keep dying and leaves are mildewy (could be a tropical thing?). The tomatoes, capsicum and egg plant are growing slowly (compared with potted plants) but looking healthy.
I have been feeding the fish pellets 3 times daily and all being eaten in couple of minutes (at times the water appears to be boiling with feeding fish). Today the water readings are: Ammonia 0.25, Nitrites 0.25, Nitrates 20-40, pH 7.4 (buffered with shell grit), water temp 30. Up until now the system has had 0 ammonia, nitrites and 20-40 nitrates. Should I be concerned? Should I just hold off feeding and for how long? Should I do a water change? Is this a normal occurance due to fish growing more rapidly than grow bed bacteria?
Any advice would be most welcome. Cheers.

[Murray]

In a balanced system the pH should gradually drift down in the absence of any buffering. Are you adding anything to buffer the system such as shell grit or egg shells ?
Above pH 7 Ammonia becomes much more toxic to fish so I would drastically cut back the feed to keep the ammonia in check.
Go really steady on the feed until the ammonia drops a bit and the pH starts to drift down. It will take several days of bare minimum feeding to see some movement down.
Trouble with barra is if you stop feeding them altogether they start looking hungrily at their mates. So it will be a delicate balancing act.

[Outbackozzie]

Looks like you may be slightly overfeeding, pushing the system a bit beyond what it can handle.

[Rich]

Murray, The system is buffered with shellgrit as I found the pH constantly creeping down and have read that Barra prefer a slightly alkaline environment. I know that ammonia is more toxic at higher pH. Should I remove some of the shellgrit (in 2 stockings) or is this all overkill and just need to be less enthusiatic with feeding and allow the system to balance out. I was enjoying the growth rates of the fish but maybe less food is the go.

[Murray]

Less food is the go, also it might help to get one of the stockings out for a little while to allow the pH to drop back just a little.
There is really nothing wrong with the pH being a bit over 7 except that the ammonia becomes a problem above 7
So if you feed less then the pH can be up a bit.
You will possibly find that your good bacteria colony will gradually pick up a bit to handle the ammonia. It would appear that you have quickly upped the feed amounts and this has caused a bit of an imbalance.
Change in an AP system needs to be gradual and measured.

[Rich]

I've added some "cycle" bacteria and held off 2 feeds and ammonia and nitrites are now back to 0. I think just a case of too much feeding. I guess I'll just have to be more patient with regards to growth rates.