Backyard Aquaponics
A place to discuss aquaponics

Rob, do one bed at a time and disconnect your return line. Better to dump the water while you are cleaning it and not conteminate the rest of the system. Good luck cheers

That's what I had in mind Bear.. Will do the one over the sump first & use the waste to water the gardens.. Mid next week I will do another & then next week end I will do the last... Don't want to do them all at once in case it upsets the bacterial balance + I can't store that much clean water to do the wash outs..

Here is tonight's readings..


I bet you by morning the levels will all be fine again
Shall space out the feed tomorrow to see if that helps..

How long after feeding are you taking samples? If you are still feeding with these very up down results, then try not feeding for a few days and the watch your results.

With regards to anaerobic zones, with that much air your water should be well aerated. As long as your system is flowing OK I don't see how there would anaerobic zones. I have a much smaller pump in 300L of grow bed. When I moved house the entire bed was mixed up and had no water for over 24hrs and I didn't get any readings.

It may well be that your bacteria is slowing down with the cooler weather and you feed rate is still high. Very high for that much grow bed IMHO. Personally I would not be feeding at all until system stability returned or I knew what the cause was.

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I test before feeding Rsevs.. This afternoons test was done many hours after the morning feed.. They went without feed for 4 days after the huge spike yet it still has been fluctuating afterwards..


I have had a look in the bottom of the beds & there are solids all through them so think that there may be spots where the water isn't really flowing through the muck, if that makes sense.. I don't think the stock pile of muck is being fed with fresh o² so the bacteria might be stripping o² form the stockpile of nitrates (NO3) reverting it back into nitrites (NO2).. The bottoms of the beds, being IBCs, are not flat so there are low spots that could be aiding that..


I am using Rupert's feeding chart I mentioned above as there is really no other guide that I know of..
Weight is 200g+
Water temp is 24-26°C
So by going by the chart I should be feeding 5% body weight 2 times a day..

30 fish @ 200g = 6000g
6000g x 5% = 300g so that is way over what I have ever fed the fish (120g max before the spike & also 2% of total fish weight).. I have dropped it to 80g this morning & still got the spike.. Like I said though I do expect it to drop to near 0ppm by the morning & shall post the results..
There is also 900l + of grow bed & that appears to be in line with other systems I have seen on BYAP & Other sites for 30 fish..

I think I am on the right path with the solids build up in the beds & think that after the beds are cleaned out I will see a reduction in the Ites.... Not a lot of info out there on cleaning beds or solids build up & how they affect the nitrogen cycle that I can find unless they are hidden in threads..

Even though I was peeking at the start I am really enjoying getting to the bottom of all this

Just to give you some idea of what a 100L constant flow collected (solids wise) in a few months have a look at this





That bed was on the system for 7 months... Didn't show it in the clip but it took 8 flushes to get the water running sort of clean..

The bed over the sump being up & running for 18 months...
The 2 beds off to the side have been on the system for about 8+ months now so am not expecting them to be as bad as the first large grow bed but still messy..Wonder what I will get out of them


I do know the veggie beds will love what ever solids I pass onto them

I posted the chart...as a guide... it's actually Stuart Rowland's "optimum feeding strategy for Silver Perch"...

Designed from an aquaculture perspective....

It has still come in handy as I couldn't find any that were for jades when I went looking... Do you know of any that would be useful for us small fry Rupert ?? I know there are always variables (like bed volume & water temp) but something would be better than nothing...

It's a pretty general "optimal" feed strategy.... regardless of species...

Just pointing out that the design perspective... is maximised growth rates... and best FCR... in an aquaculture perspective...

Most backyard APers probably wont be feeding at these rates... because, as you've seen ... most backyard AP systems.... don't have the filtration capacity to deal with the feed levels... especially if just relying on gravel grow beds...

(Or they're overstocked....)

People often forget... that the original filtration:tank volume ratio was 2:1.... whereas 1:1 is now almost universal... and IMO, with just media beds... under-filtered (when trying to pump the feed into the fish)...

If you want to grow/feed your fish optimally... like they do in aquaculture... then you probably need to implement aquaculture type filtration... as many are now doing...

Or keep your stocking density lower...

And... Im sure it will be somewhat controversial... but having pulled down my beds several times over the last few years... for one reason or another...

I've come to the opinion.. that running constantly flooded grow beds... (and skimming water from the top of the flood via the standpipe... results in the solids settling out in the beds... and gunking them up... in 1/3 -1/2 of the time of siphoned, or timed F&D...

This certainly seems to be particularly true when feeding heavily... for high feed, short period growth fish... like trout...

The corollary... would perhaps suggest that siphoned, or timed F&D... may be re-suspending a degree of solids out of the beds during each drain period...

I have come to the opinion that they make a great filter as well Rupert **nods** Thanks for the help..

Yesterday we had .25ppm morning & night & back to trace today..

Cleaning out the bed over the sump tank today... Anyone want to come help ??

Meant to update on the Nitrite issue but have been a tad sidetracked of late.. It ended up all settling down after I cleaned out the grow bed on top of the sump.. was very mucky down the bottom of that one as well..



Think I have a few ideas on how fix this problem in these IBC beds.. My siphon housing & pipe work needs to be altered as well I think so will be altering them as well..
All levels are back to normal now as far as I can tell.. Did a clip on nitrites & what I learned through all this..


Thanks again to all that helped me with that...


We were very lucky to have 4 Jades given to us to try a week or so ago by Paul, Have thanked him before but shall again
Time to come clean now... Was the first time I had filleted a fish but think I did a ½ decent job..

Scored them a tad deep methinks..

They cooked up great but the amount of oil/fat surprised me..

Was fine though as it seasoned up the quinoa salad nicely..


Off to the "Free Workshop Build a Backyard Fishfarm in an Afternoon" being put on at the Westfalen Community Garden at Collingwood Park..
Thinking I might give it a shot myself seeing as we have all these wicking beds that would love some fish water in their diet **nods**

Should be a good day there Rob, see you there mate

hey Bob, Ive been filleting fish for over 30 years and i reckon youve done a good job on those jades
, youl get better with practice. the proof of the pudding is how much flesh is left on the frame when you've finnished.

Thanks Blind Freddie.. They were cut very close to the bone... I could show you but they are in the freezer waiting to be turned into soup or stock

Shall see you both at the do on Sunday hopefully

Just finished reading through this thread, and I have to say.... Amazing work! Very informative in regards to plumbing and set up.

Great job on the fish btw. Been a Chef for a few years now. Pretty darn good for your first time.