Backyard Aquaponics
A place to discuss aquaponics

hmm - something like this one? That's a good idea - wonder how well they work?

http://cgi.ebay.com.au/solar-pool-heater_W0QQitemZ230273204169QQihZ013QQcategoryZ149235QQssPageNameZWDVWQQrdZ1QQcmdZViewItem



I know - i reckon we potentially have a couple of months of ideal AP weather in Nov-Dec before the scorching summer temps set in It's such a bugger of a climate to try and garden in. That's why I am so attracted to AP, but the temp fluctations throughout the year in Canberra appear to cause a fair few hassles for an AP system too... Just trying to work out if it's worth persisting with trying to set up the bigger system if Canberra's climate means we will need heating in winter and then cooling in summer...

Insulation around the tank can keep it cooler in summer,,,depends how you set things up.

Margate, you will just need to use the right type of fish. By next winter your system will handle the colder temps fine.

Thanks OBO - but it's this concept that's doing my head in at the moment. I'll try and explain what I'm struggling with. Take a Canberra winter, which is really cold (eg temps of down to -7 o/night, day time temps of 8-9 deg). OK - say I choose a fish which suits those water temperatures (eg goldfish, eg trout). Now I plant vegies which grow well in Canberra winter (eg broccoli, caulis etc). All good so far. But what about the nitrifying bacteria that drives the system??? As I understand it there's no activity at 4 deg. But does that mean that the bacteria stops working all together, or just stops multipying?? Say for arguments sake you have an established 'colony' of bacteria in a system before the cold weather hits, will this 'colony' keep ticking away at these low temperatures, even though it might not be multiplying? Or does it shut down completely, meaning that the system is not viable over winter at those temps? Apologies - this probably sounds really stupid - science is NOT a strength . If someone can explain how cold temps affect the nitrogen cycle in an established AP system in simple terms I would be SO grateful.

What are your actual water temps Margate... as opposed to your air temps....??

Rationale.... your water temp will definitly be higher than your overnight air temps and probably at least as high as your air temps during the day....

You're pumping water through the beds during the day (probably not at night).... which gain "some" heat from the growbeds during the day....

It's that water temperature that the bacteria are living in... as ultimately are your fish....

Obviously a greenhouse helps maintain growbed temperatures... as does heating the fish tank/sump...

I tend to think you're right about the bacteria not "multiplying" below a certain temperature but still actually surviving.... love to know for sure...

I have water temps of approx 10 deg c. Growbed temps after a night of no water, get down to around 2 - 4 deg c. ( we get 0 deg c mornings)

I have no worries keeping up with 50 trout, I get no readings in the water at all.

I dont know what temp the bacteria stop working / dieing at, but I havnt found it yet.

die if they are frozen, slow down at your temps, but its all about balance

I think they slow down, but don't stop. My system seems to have recovered and is now actively processing Ammonia - maybe the bacteria adapted to the cold, or maybe 8 degrees is sufficient for it to do it's thing, or maybe I just put in too much urea and it was cold and it took a LONG time to process - I'm not sure. The bottom line is that I now have Ammonia of zero and Nitrate of 10. So it's going, I've had to use a 300watt heater for a bit, but this is my first winter with this system, and I'm going the greenhouse for protection and heat (and shadecloth over the top in summer to reduce temps).

As said above, the bacteria live in the water, so if you have your tank in a shed (Jim Atkinson has a plot of his water temps in his shed somewhere on this forum, or maybe you can PM him) and you regulate your temps then you'll be fine. If you heat your water using the solar pump, you'll be fine. If you do both, you'll have even better control.

There is plenty you can do. If it makes you feel better, think of yourself as a pioneer, thus far I only know about 2 systems actually working in and around the Canberra region (I'm sure there are more, I just don't know about them).

And anyway, people envy our cold temperatures because we can grow trout!

Half the fun of AP is the trials it puts in front of you!

Margate, how are the temps/levels? A friend of mine has buried his tank and has had the following temps:

Friday 2am 9am Monday 8am
Tank: 8.2 6.3 4.8
Ambient: 10.3 7.5 2.3

Which shows how much 1000L can swing even when buried (it is not covered though, and it's got an air gap between the soil around it).

Sorry gemmell - haven't logged in for a couple of weeks. temps in the morning this week have been down around 4 degrees again. Didn't measure this morning but reckon it might have been even lower still - pretty severe frost. Will post test results from last couple of weeks later but just quickly - both ammonia and nitrite peaked at around 1 and then have both dropped to 0. Nitrate readings peaked at about 10 but since then have also dropped to 0. Not sure if that's because we need to add more goldies to the system or because the plants are just sucking up all the available nitrates. Plant growth is slow but there has been a little bit (of growth that is). Will post some updated pictures soon.

Sounds like you've cycled Margate... add a few more goldies... or up your feed a bit and measure...

Then again I guess the goldies mightn't be eating much anyway... what sort of water temp do you have??

My temps are up around the 8's and 9's in the morning, I think putting something over it helps a few degrees - the frost doesn't land on the water and sap the heat out.

Ditto that Gemmel.... covering the tank used in the solar array trials had a marked affect....

About 5 degrees I reckon...