Backyard Aquaponics
A place to discuss aquaponics

Hi Jamie,

Welcome. I have had fish in my tank for 36 hours so take this advice from whence it comes :-)

Easiest way to control the pump output IMO is to get a pump that is overspecced for your application and add a bypass back to the tank with a ball valve to control it. That way you can balance the required flow for the growbeds, don't strain the pump and you get 'free' aeration. If you add ball valves to the inlets of the beds you get an infinitely variable setup.

I bought a 4 in one test kit on saturday (amonia, nitrite, nitrate and ph) but I'm in South Africa so I doubt if the pricing would translate. It cost me the equivalent of 60 oz dollars.

Jamie, I have attached a photo of the flow chart from my pump. It is one of Murrays made in Italy Saltwater pumps. Hope this helps

Juist to clarify a point. AA was right. 6 kilos per 100 litres is really pushing the boandaries of friendship with your fish. I am aiming for around 2 kg's of fish per 100 litres with a growbed ratio a little under 1 to 1, and I reckon I will have to add grow beds as the fish get to that final stage.

6 kg's is a MAXIMUM guideline if your system is established and you are really good at it, like AA said

Jamie a fair few of us seem to be using this test kit: http://www.theaquariumshop.com.au/shope ... r+Test+Kit

Thanks Monya,

Good link, I was looking for a good test kit that does Nitrates.

Nova

Easy to use too, and it has little hole to sit the test tubes in.

Also with that test kit you can get just the chemical bottle you have emptied replaced at some pet stores (rather than buying a new kit)

Thoroughly disagree on 10 000 litres takes forever to balance and/or requires 500 fingerlings....

1 kilo fish is 1 kilo fish. In 25 litres or 10 000. Cycle it and plants will begin to feed, so what if it's a bit slow, just do it.

Who gave the magic startup number cos i started my herb garden with 1 whitebait initially,

Test Post - I posted twice before and they didn't appear!

(Edit) - ok that appeared

Thanks for all the tips and info everybody!
I guess the advantage of having too big a tank is that it will be harder to kill the fish

Has anybody got any practical data on flow rates through siphons?
There are some pretty daunting equations out there. I saw a table which showed flow rates but for extremely long siphons (metres). What I'm looking for is for siphon rates from a header tank & from a grow bed.

I am assuming that to make a flood and drain system work (without power) using auto-siphons, I would need an auto-siphon from the header tank and then auto-siphons exiting each grow bed.

I figure, if x is the pump flow rate into the header tank, y is the auto-siphon flow rate exiting the header tank and z is the auto-siphon flow rate exiting the grow bed, z must be greater than y and y must be greater than x.

So to design it properly I need to play with:

1) pump flow rate (x)
2) volume of header tank (and height)
3) exit siphon flow rate (y)
4) water capacity of grow bed(s)
5) grow bed exit siphon flow rate (z)
6) Duty cycle of water in grow beds - how long wet, how long dry.

Its a lot to digest (for me)

But knowing the siphon flow rates would be critical.

(still waiting for my book and cd)

Cheers
Jamie

Steve is right Jamie...it will take a little while for the tank to build up nutrients depending on how densely you stock it.

AA - I was simply pointing out that his plants will not get enough nutrients to thrive. Grow, yes, just add water. But A tank that size will take a very long time to mature. Not saying don't do it. Saying keep in mind.

I just cycled 600 litres in record time (for me) to the point of explosive plant growth.

I had the newb water, the trying to swing Ph water, pea soup, and now plants going nuts. In 2 months. pH 7.2 rock steady.

This with 1 kilo of fish. Is there enough bacteria for the planned 18 kilos. Definately not. Is it fully mature, yes!

If I waited on the big fish delivery I'd be months behind. This is a lot of water good to go with very little fish.

There is no rule on how long a set volume takes to mature, to my knowledge. Put 10 ml of the right bacteria in 10 000 litres you've started the process - put none in = nothing (in comparison, some will arrive airborne). 6 months with no bacteria, stuff that, get bugs n go for it.

Put 500 fish in...... and cross fingers it'll cycle fast enough?

No disrespect, i think it's still a bit of a grey area, I know what I've done, seen, and read about. I'll always go on what I've actually seen and done myself.

AA - Completing the nitrogen cycle is not really what i was getting at. I was trying to indicate a minimum ratio to start at. Jamie could easily inject bacteria into his filter and cycle the tank in a few days, I apologize for not clarifying. He could easily put 500 fingerlings into his tank (after it is innoculated) due to the massive amount of water that would buffer the spike and he would not have fish mortality.

My system is 3,400 liters, roughly a third of what Jamie is proposing, stocked lightly with 12 kilos of fish. That's roughly 283 liters per kilo of fish, which I find to be on the light side if I wanted to do heavy fruiting and planting. I am a bit surprised you are achieving such success with such a minimal ratio, but I suppose you are growing herbs mostly. My experience with systems less than 1,000 liters is they gain nutirents quicker and are much less stable or tolerant of high stocking densities (which is probably where alot of caution from this forum kicks in) and can change parameters faster, resulting in higher fish mortality (as many on this forum have experienced). However, when I tried to grow anything more than herbs in my current system with a lighter stocking density than 100:1 it was not productive because water was too dilluted. If I went with your stocking ratio recommendations of 600:1, it would not have worked. Jamie's tank is three times mine (and 16+ times yours), which means 35-36 kilos of fish in his tank would match my ratio, and 16 kilos would match yours. To be fair, using your ratio, that would be 32 fingerlings (16 kilos of fish after non-sexed dress out). Not sufficient as I've experienced in my system, so therefore a potential pattern emerges. As tank size/system increases, so does dillution and buffer capacity. The question is will Jamies tank be too dilluted at 600:1? Yes. Will it be too dilluted at 283:1? Probably. I suggested 500 fingerlings (a ratio of 10,000:1) knowing that Jamie could build his grow bed space as they grew, and knowing that 500 fingerlings would grow out to roughly 125 Kilos (sans mortality and accounting for only one tank and not sexing the fish therefore limiting dress out size to .5 kilos) with a final ratio of 80:1 which is still a far cry from dense stocking ratios.

Thanks MF, - I was trying to find a way to cycle a 1,500 - 2,000 litre tank and not have to change volumes of water and to gradually increase grow bed size - you have cleared up a few points that I have been trying to work out and have put me on a different tack

Ell

Glad I could help. So did you just acquire a new tank?

That should read 300 liters to 1 kilo sorry. I meant 100 gallons