Backyard Aquaponics
A place to discuss aquaponics

Your Dad...gave you that "pig" for a wedding present...

I think I like your Dad...

Excellent Cheers.

It doesn't look like there's any plants in the GB's? Or are they outside of the photo? (Just wondering what's supporting the trout).

Looking good!

He only just re-did the system (lining or coating the galvanized tanks and beds because of the zinc issue) so I suspect any plants already growing are still tiny and not visible.

The fish have been in for one week today! Apart from the one who decided to go travelling, no losses.


The bacteria are supporting the trout at the moment. I haven't put any plants in yet, as I've been cycling it continuously and watching and waiting for the colonisation process to mature. I'm happy with the nitrate load now (~7.5 ppm) so today I hope to put some plants in. My wife has been sprouting seedlings like it's going out of fashion . We're looking at basil, coriander, lettuce, and we'll also try some brassicas (broccoli, cauliflower).

The cycling is looking remarkably good for one week. Near-optimal temperatures (water continuously ~15 deg C) have helped:

I thought optimal temperatures for bacteria growth were mid 20's.

I'm suprised at how quickly it's colonised. In saying that, I let my old system go "fallow" for about 3 months, it didn't even have water flowing through it, then when I changed the water out, put in some fresh stuff and got it running, it was processing in no time. So I've got an inkling that once you're established once, some manage to survive no matter what, so subsequent bacterial re-establishments are very quick indeed.

a big bucket of cycled gravel is like starting with an aged filter... and the gravel was from a system that was about a year old.

Yep, it's the gravel that did it I'm sure.

From what I can gather, the bacteria are probably growing at a rate of one doubling per day, so starting with 20kg of innoculated gravel is a massive boost.

I've started feeding the fish a bit more, and have consequently noticed a second ammonia spike. Good to see the system behaving the way it's reported in the textbooks!

I've planted a selection of lettuces and basil / coriander, plus a cauliflower and 3 onions to see what happens. Also a late-germinating capsicum (but that'll never amount to anything in the cool weather).

20kg is a good amount of seed media. I started with maybe 10 bits of aggregate from a fishtank... I'll have to remember that next time. 20kgs of media gets it cycled in no time.

Hmmm....



I'm guessing the secondary ammonia peak is nothing to worry about? It occurred when I (a) started feeding the fish more intensively, and (b) went from continuous flood to flood/drain. So it kind of makes sense.

What worries me is the nitrite (NO2). The colour scale I'm using for the drop test makes it very hard to distinguish between 1ppm and 5ppm. I think a spike to 5ppm would be unusual as ammonia has only gradually gone back up to 1ppm, so I'm hoping NO2 is only 1ppm. Still, this is potentially a dangerous level.

pH is hovering around 7.6, and temps (measured in the morning) are sitting around 14 deg C. At a guess I'd say the temp probably rises to about 15 by the evening.

I'll scale the feeding back a bit (just keep them interested), and I've adjusted the flood and drain cycle to have mostly flooding during the day (only a few 30-minute draining times) and mostly draining during the night (one flood per hour).

I'll take some readings this afternoon as well for comparison.

Wait, scratch that.

I've now read another post that said to keep the system continuously flooding during the initial cycling phase until the biofilter is properly established - so I've now put it onto a (roughly) "flood 4 hours drain 45 minutes" regime, round-the-clock. I figure I need to have a few drain times in order to oxygenate the plant roots.

So how are they?

Things are looking okay at present. Nitrite is consistently high though.

No confirmed fish losses (unless the visiting heron took a few the other day!).

Current readings are:
NH3 - 0.25ppm
NO2 - 1 to 2 ppm
NO3 - 20 ppm
pH - 7.4
Temp - roughly 11 degrees

The NH3 --> NO2 process is working well, but the NO2 --> NO3 seems to be slow. I suspect the low temps are hindering bacterial growth.

Plants have not been doing much, despite the high nitrate concentration. (Or is 20 ppm not high?)

I think the lack of sunny days lately, coupled with the almost continual flood regime, accounts for the lack of plant growth. I've put a few more drain times in the cycle, and we're scheduled to get some reprieve from the winter weather over the next few days so we shall see what happens!

Plus it takes time for them to get over transplant shock, plus they don't grow much if their roots are cold.

IMO... continual flow systems... and trickle tower filters ... result in trace nitrite levels... for prolonged periods... or even indefinitely....

I think when people say to keep the system running continuously during cycling, that just means constantly flooding then draining... as in time out how long it takes for the beds to flood and run the pump for the closest amount of time you can to that and then let it drain for about the amount of time it takes for the bed to mostly drain then flood again.

Constantly flooded beds probably don't provide as much air to get the bacteria going as well and beds left drained for overlong are not providing any filtration while they are sitting idle.