Backyard Aquaponics
A place to discuss aquaponics

Thanks MDP! We are quite pleased with ourselves, though haven't done trout before so don't know how that growth rate compares to others.

We bought our barra from Golden Ponds, and they were about 500g each already and grew out to 1.2-1.5 kg. It was great, but we would probably like to get smaller this summer. We lost some early on, which we think was partly due to poor handling/transportation of such big fish. The cool temperatures in Perth last spring didn't help either. We haven't started looking yet as our water temperature in the pool is still 17 degrees, plus we are wondering whether to just put the perch in.....

You mention residual nitrite readings for the pool. You might want to add extra aeration. It has been noted that constantly flooded beds often leave a system with residual nitrite and I think this may be due to reduced dissolved oxygen in the water in the flooded beds.
Since you are using a bio-filter (I didn't read back through your thread though so don't know what kind) if it is a sand filter, you might be running out of dissolved oxygen which could be creating an environment where certain bacteria are converting nitrates back to nitrite to be off gassed as nitrogen. Extra aeration could 1-assist in the offgassing or 2-get rid of the low oxygen situation and stop the conversion of nitrate back to nitrite. Depending on where/how the extra aeration is applied.

[quote="TCLynx"]You mention residual nitrite readings for the pool. You might want to add extra aeration. It has been noted that constantly flooded beds often leave a system with residual nitrite and I think this may be due to reduced dissolved oxygen in the water in the flooded beds.
[/quote]

Interesting...this is actually what we did, though out of desperation really. We had similar yesterday but this time we didn't do a water change just added aeration. Although we use the bio filter (with those sponge type pads), we didn't disconnect the pool pump when we set up the bio filter, but left it as an aeration backup. We filled the pot with Zeolite instead of sand, and run this for extra aeration (the pipe into the pool is cut and points up into the air to give a fountain effect) and to remove any excess ammonia. It is very successful in a short time, though we are not sure if it has an undue effect on the bacteria that should be present.

You mention constantly flooded beds...we don't have grow beds but do have the floating rafts. Could this cause the same problem? We have only had the unsettled nitrites this last month, up until then it has all been very stable all year. The floating rafts of veggies have probably been in for two months or so. The water has been dirtier this last month too, whereas before it was quite clear. I know feeding in excess can cause problems, but I don't think we are doing this. We work on about 1.2% of biomass, and resist the temptation to keep feeding (because they sure would keep eating!!).
Any advice gratefully received!

No, I don't think floating plants would be causing nitrites. The flooded beds or bio-filters only cause nitrites if there are zones without enough dissolved oxygen (RGS filters, look it up for more info on that topic.)

More likely is if there are places where solids could have been building up, that can do all sorts of nasty things to water quality as a few people have discovered this past season. Air stones can help for certain situations of this.

The latest update.......
After the success of the trout, we put barra in again in October for the warm weather. All are going very well, so much better than the very first time we put them into our pool...over 12 months ago! We have also had very small perch in an IBC since January. We lost a few of these, and weren't keen on the IBC because the water greened up far too quickly so we couldn't see the fish. We have now made a floating cage to go in the pool with the barramundi...and so far so good!! Hopefully this will be better conditions for the perch and they will now grow better!

Today was pretty hot in Perth, so we went for our first swim of the summer in the pool with the barramundi! Very nice it was too...especially when followed by a gin and tonic!!

We have also been experimenting with floating rafts for veggies that grow in a salt content of 5-6 ppt. The silver beet/rainbow chard, spinach and amazingly the basil have all coped really well and we are now cropping.

Very cool Deb and Mac

Hmmmm, that idea didn't work very well. There seemed to be a big surge of filamentous algae, not only on the floating cage but on every surface in the pool. We weren't sure if it was because the netted cage made a larger surface area available, or whether it was a seasonal thing. We ended up taking it out and putting the perch back in the IBC.

The barra are going very well though, and with all the warm weather we have had they really eat well! We are starting to harvest by scooping with a net when they are feeding, but haven't weighed any yet.... we certainly get decent sized fillets though!

We have also been experimenting with plants (floating in rafts) and the salt level (we keep the salt at around 5ppt for the fish health). Spinach and silver beet both do really well in the high salt, with the spinach doing much better than in the veggie garden!

Hi Deb and Mac,
I was just out in the garden and happened to be thinking of you both and wondering how things are going, so I am not really surprised that you just posted here. Would love to see a photo and glad that it is all going well. Faye

Hi D&M
Good to see you utilising your pool for both fish and people
I would definitely be adding grow beds for biofiltration and especially adding salads to that good looking harvest of fish.
And a little word of caution
I had a large pool in a previous house in Alice and would regularly have a quick skinny dip late a night. I would never turn the outside or pool lights on so as not to shock the neighbors however on more than one occasion I spied Western brown snakes having a swim and this was only because of moonlight nights, so who knows how many I may have swam with previously, after that I made it a habit to do a quick torch search of the water before diving in. Not sure if it's true but I have been told that snakes cannot bite when in water but I don't intend testing the theory

Hmmmmm, glad I don't live out your way DR.......

Funny how most people panic over snakes
yet more people are killed by falling coconuts and bee stings
and we think nothing of jumping in our cars that wreak untold deaths and injuries.

At least we are safe from falling coconuts in Alice!

What about dropbears ? Those things'll kill ya !

[quote="desertrat"]
Good to see you utilising your pool for both fish and people
I would definitely be adding grow beds for biofiltration and especially adding salads to that good looking harvest of fish.
And a little word of caution
I had a large pool in a previous house in Alice and would regularly have a quick skinny dip late a night. I would never turn the outside or pool lights on so as not to shock the neighbors however on more than one occasion I spied Western brown snakes having a swim and this was only because of moonlight nights, so who knows how many I may have swam with previously, after that I made it a habit to do a quick torch search of the water before diving in. Not sure if it's true but I have been told that snakes cannot bite when in water but I don't intend testing the theory[/quote]

Hi Desertrat
Maybe the grow beds will come...at the moment we have floating rafts, but also a very large veggie garden where we grow most of our own veggies. This is part of the chook run, so when one of the three beds (about 5mx5m) is finished the chooks go and scratch about and get it ready for the next crop. So we have no shortage of veggies!
Snakes at night....hmmm....must say we often go out to the pool at night....we get plenty of tiger snakes here, and we certainly have seen them at night, but never in the pool! I wonder if they like to swim too! We might have to start looking too!
dandm

We mainly get Western Brown's but most snakes do like to swim and I have witnessed several Tiger Snakes swimming when I lived in the Southern part of Australia so probably wise to check with the torch, hate to hear that you dived face first on one

Well, the barramundi are now in the freezer! We got them at around 300g and the largest were 950g, most around 800g, and a couple of smaller ones. We are very pleased, it is certainly enough in the freezer for us!

We refined our catching method further (though it still involved Mack getting wet!). We used the screen doors we described earlier, so we ended up funneling the barra into one small area of the pool. Then scooped them out with a net and placed in the floating cage. This gave us time to prepare a few at a time (and gave a bit of breathing space in between!).
We had caught five over the last few days (just by netting them as they were feeding) and yesterday did the remaining 25 (hmmm, still to clean up all the scales!). It all worked very well.....now for the trout!