Backyard Aquaponics
A place to discuss aquaponics

slowly, slowly. Rather than getting more fish at that point I'd be inclined to increase the ammonia load progressivelly to build the population of bacteria before subjecting the biofilter to a load of new fish. I would do this using urine - just don't overdo it at first - start low and test often.

Really? Urine? Eww!

We were actually thinking of putting in half a dozen perch at a time (can get them for $3.80 each, not brilliant but it's affordable in small batches), rather than another batch of 100 from Ausyfish.

Alternatively, could we chuck in some extra fish food before we get the extra fish? I'm led to believe it breaks down into ammonia any way (and overfeeding at the start seems to be one of the factors contributing to the high fish losses in our system). I'm just not sure how enthusiastic Dad will be to piss in his fish tank...

Extra food will create extra ammonia, but also may provide grounds for fungus. Digested fish food would be better.

VB is serious about the urine. Technically speaking, it should be sterile and free of contaminants. If Dad is on medications or has health problems or anyone eating from the system has a suppressed immune system, I don't recommend it. I'm pretty conservative on that one, but then, my husband falls in to all of the above categories.

You could try cycling up with bottled ammonia if you are absolutely sure it has no added soaps or surfactants. Otherwise, your idea of adding fish slowly sounds absolutely grand. Most of us don't have the ability to buy our fish 6 at a time. It's a hundred, or not at all!

Considering the cold I would recommend going with cold water fish, if and when you get more fish. Just some goldfish would be ideal to start cycling properly.

I would be inclined to call it a new beginning and treat the cycling process as if it was a brand new tank. Get a few fish, maybe some yabbies as well, get an ammonia substitute if you don't want to pee in it. A chemist may have pure ammonia or a lab supply place.

Cycling in winter should begin after about 6-8 weeks if at all, keep in mind they like a pH of 7.5 -8 and an ideal temperature of 30 degrees. Cases show that their production rate is only 50% at 20 degrees. So growth in a cold environment my be very, very slow. Nitobacter is less tolerant to low temperatures so ammonia processing will be slower.

Right now we've ensured the water temp will stay above 10 degrees, but that's only in the tank - the growbed might cool down at night below this, almost to freezing on the coldest nights. So, the bacteria on the gravel might be having a really hard time multiplying.

2 days ago, ammonia was 1-2ppm. Will keep an eye on it, and nitrite and nitrate levels too. When the ammonia starts to come down seriously AND nitrates start to go up, we'll assume both sets of bacteria are doing their job.

Dad isn't really keen for goldfish because he doesn't want to have to pull them out and kill them when he puts silver perch in! But, if perch and goldfish get along well though, perhaps I can convince him to get some goldfish and keep them even after getting some more perch.

jim i have had goldies in with my silvers all the time ones almost 6 in long now . ones only small some of the silvers are 8 in now

Goldies and silver perch harmonise well....I had a problem in that I introduced SP which were larger than the goldies and they didn't co-habitat at all...I started with 10 goldies and they cycled my tank very well (200 litre tank size tho)

Sounds like we might do well to go with some goldfish in that case. In small quantities, they're certainly cheaper than perch.