Backyard Aquaponics
A place to discuss aquaponics

Just been thinking about ways of extending the Barramundi/Trout seasons here in Perth - and wanted to float an idea. If it has already been discussed, can someone please point me in the right direction.

I have seen lots of discussion about cooling and heating to extend the seasons for the above fish, but was wondering about adjusting the pumping schedule.

My idea would be to have two tanks, one for trout (T) and one for barramundi (B) or silver perch.
Firstly in the warmer months (or maybe even just warmer days?).
During the day the (B) tank would cycle into the growbeds, while the (T) tank remains dormant (with auxilery aeration).
Once night has fallen, (B) tank pumps into the growbeds one final time to cool them - then (T) tank pump kicks in and cycles through out the night.
The pattern then starts again when the sun comes up (or when the temperature increases).

The (T) tank would be covered and partially buried - as well as shaded, with constant aeration. To help reduce temperature gain.
The (B) tank would also be partially buried and covered to reduce temperature loss.

In winter the (T) tank could also pump during the day (maybe alternating with the (B) tank) - or if the cooler the water the better, could keep on the night rotation.
The (B) tank would pump only during the day, and the returning water would cycle through some sort of solar heater to increase the temperature. Maybe the air used by the airpump could also be sourced from air heated with in the house.

My premise is that when the temperature is hot, cycling through the growbeds increases the temperature of the tank. When the temperature is cold is reduces the temperature of the tank.

Does it help to only remove a small portion of the tank water at any one time? If you used sequencing, you could take maybe just 5% of tank volume out at any one time.

Justin

Well not sure if it would really work... but I remember the days of trying to keep the temperature down to keep my trout alive and also trying to keep the temperature up to keep my barra alive during the transitional period... it could be a pretty stressful time, making ice cubes, testing water, adding a heater..

Not sure that I would be willing to do this for an entire season.. ie... worry about the barra throughout the whole winter... or worry about the trout throughout the whole summer...

IMO, in order to get this done right without much stress, you will need some form of automation system... something you can program a set of guidelines, to determine when to pump for each tank, daylight sensors, temperature sensors for both tanks, air temperature sensor... and there is of course fine-tuning of the guidelines...

As if you (or at least for me) are to do this manually, you (or at least I) will go crazy as there are too many variables to make the right decisions all the time...

heaps of discussion shiv, but I have decided that in Narrogin it's not going to be warm enough for Barra and it's well documented I am not a fan of Silvers as too slow growing but maybe better suited to Perth, I have trout still going and water yesterday was 23.5c, my tanks are under cover and partially buried, temps have been mid 30's to 42c this week, cool nights get the water back to 18c but we had a warm night last night and water was at 20.5 this morning, I expect water will get above 24 today which is touching the limit but have added extra air so hopefully they will last until tomorrow arvo, I personally don't think running both is possible

Good point, I would think you would probably need the following:

2 x pumps - one for each tank.
2 x sequencing valve - to fill growbeds sequenctually.
a value that is toggled when a pump is started - either electronically or mechanically by water pressure coming from each pump.
A computer relay board, to control pumps and valves.
Temp sensors for each tank, for ambient temp, for temp in grow beds. I bought a little unit for $50 that has 4 sensors - and a serial input into your computer.

I think you can do without the light sensor - as you would just factor in the temperature.

Would then be pretty easy to write some software to sequence it all, just not sure if it would be enough - or if you would need to add extra cooling?

Does the idea sound okay, or full of holes!

Okay, presuming that you can not keep barra through winter - do you think keeping the Trout through summer is a possibility? I realise you have a lot colder nights your way than we do.

Do you still pump though the day when the temp gets high?
Or do you only pump at night?

Justin

Justin we have similar conditions to Perth other than we don't get a sea breeze although we have some slightly cooler nights, I was hoping to go 12 months with trout but I think I may be defeated, I think the short answer is no, the long answer possibly but with a lot of *frack* around,

Yep... it's the nights that get you when you're trying to keep tank temps down... cool/cold nights.. no problem... but get a couple of warm, or cloud covered nights in a row...

And you'll start the next day with elevated tank temps.... and it just keeps compounding...

The larger the tank volume the more (relatively) stable temps will stay... and so far, with 6000L of water... my trout tank hasn't moved past 25 (for a day - hot).... but has rarely dropped below 20-21 even with a series of cooler days and nights...

I would say that the idea is full of holes but full of possible pitfalls... one wrong move or something outside your control (ie. power failure) it could throw the whole thing out of the normal sequence and into HSM... your stocking levels I would expect would have to be kept at minimum stocking levels for the spieces at risk...

IMO, don't work against Mother Nature, trout (cool water) and barramundi (tropical water) cannot survive under the same conditions... It might be better to keep a tank for Silver Perch year round and a tank for seasonal fishes (trout and barra)...

It is a good point, I currently have a tank full of silver perch - because they should survive year round, even if they will not always be in a mood to grow - so maybe the trout/barra winter/summer switch over is the way to go for another tank. Might do that for a year, and get some good data on the temperature fluctuations - and see if I can work out a way to keep trout happy in summer. Though it sounds like that is a road filled with grief, so maybe just keep them happy a little longer.

Justin

same rupe with 6000lt's so volume works I think, just checked and mine 22 just now may hit 23, cooler days ahead so still in limbo as to persevere or knock them on the head, may go 50/50