Backyard Aquaponics
A place to discuss aquaponics

From all i have read smaller fish use more oxygen than larger fish, a bit like the kids really, there always dashing about

Looking nice and a really fast cycle , cycling must be the worst thing in aquaponics, worse than watching a kettle boil, mines not boiled yet

Yeah, it's really odd. They're next to each other, and if anything the paler of the two gets a few minutes more sun each day. The water inlet to that GB is from a loop of pvc pipe on 3 sides of the GB with pretty substantial flow.

The only difference I can think of is that I was doing an experiment where I rinsed the roots of the seedling on some plants and didn't on others. The roots of the ones I didn't rinse are still in the punnet shape from the seedling tray.

Problem is, I forgot to note which ones I rinsed and which ones I didn't. But they were planted aaages ago - surely the roots would have grown substantially since then.

I'd imagine they'd use more oxygen per kg of bodyweight, but surely a 20g fingerling wouldn't use anywhere near the same oxygen as a 200g juvenile fish?

The bacteria near the greener one is most likely more established?

I'm happy to be corrected, but that's not how I understand it works - the bacterial colony could be in a completely different growbed, but the nitrates and other products are dissolved in the water and spread evenly throughout the whole system.

The bed is constantly flooded, but it does get a siphon put on it every few days to make sure there aren't any stagnant patches. Not that I think there are - the beds are only a year old.

Maybe it's just a bit of a stunted plant...

hence the '?'


I have plants in certain areas of my beds that don't do as well - I also think its transplanting shock and root development.

I think I'm going to just pull it out to find out one way or the other...

Heh, sorry for not updating everyone on the mystery above. Roots looks similar between the two, so I suspect it was just a bit of a dud plant.

Aaanyway - another issue. My partner's system - the single IBC one has been showing really crappy growth. I figured it was just a matter of waiting until the weather warmed up and things would kick off.

But no, it just wasn't happening, plants were looking terrible. Checked the pH and it was around 8.8!

So I put a capful of HCl in which moved the pH way more than I was expecting - down to 8.0 or thereabouts. Waited two days and put another half cap in and it was down around 7.8. Checked it tonight, expecting to see it staying where it was, but it was back up around 8.7, 8.8 again.

Is this common if using HCl or similar to bring pH down? Is it a matter of keeping adding it until whatever is moving things back up is used up?

Is there something that would be more beneficial than HCl to bring down the pH?

I have no idea. More growbeds and bacteria?

I suppose it's not helping that there are only 7 or so small Koi in there as well as a fair bit of stringy algae. Not enough ammonia being produced to bring down the pH?

Well - I've wrapped the little system in cardboard and added a few airstones. Seems to have cut down the growth of the stringy algae a bit. Still seeing a pH swing from morning to evening however. Will see how it goes after a week or so.

My 'big' system however has been going great guns. It cops a lot less afternoon sun, so I haven't had any algae issues other than a brief bloom. Have pulled a bunch of trout out for some really satisfying meals. I'm even getting better at killing and gutting them.

The plant growth has been fantastic too - really strong. Have been eating lots of Coriander, Broccoli, Chilli, Celery and Tomatoes. Looking forward to lots of garlic and lettuce soon too.

So - quick update. My system is going great guns - have just started harvesting the corn, which is delicious. Chillis cranking along, as is the rhubarb and rockmelon. Broccoli is getting hammed by come caterpillars though.

The other system has settled down nicely after I moved the Koi and converted it to peeponics for a while. I think the substantial ammonia load has pulled down the pH nicely, and now it is stocked with a bunch of SP fingerlings. Looking like it's about to double in size with a duplicated setup next to it.

All good!

Did a little work today and added this to the small system.

The top pipe has a baffle in it to keep it half flooded, and the outlet from the lower pipe achieves the same thing. Leaving it for 24 hours for the pvc glue to set, then going to fill it with hydroton, strawberries and herbs.

hahaha similar to "my ignorance amuses me."

So anyway - first update in a few years. Systems have been ticking along pretty well, plant growth has been solid, and fish are healthy.

I'm a bit overstocked at the moment, so to help things along I decided to add a filter of some sort.

25L barrel from Bunnings, a few bits and bobs and it's up and running. Was amazed at how much gunk it pulls out. Admittedly I did flush both beds a few times by popping the siphon on, so it will be interesting to see how it settles down over the coming weeks.

So what do people do with their filter gunk? Chuck it on the compost, or some sort of anaerobic digester?