Backyard Aquaponics
A place to discuss aquaponics

Thanks JP. I am good at tracking data... part of my job. So, I'll do that here and see what I can learn. Now, back to cleaning tanks... :p

Not sure if it's been posted before, but this document (page 6-7, 'aquaculture') talks about a 'new technology' called a 'biofloc system' where organic particles (biofloc) are kept in suspension where aerobic bacteria (nitrobacter and nitrosomonas?) turn it into nitrate, which is then fed through anaerobic denitrification channels, much like the RSG filter. I'm not entirely sure exactly how it works though.
The document describes an experiment with a 'biofloc system' and tilapia. Maybe it's of use to somebody.

Interesting: rather than use a gravel growbed as we typically do with AP or a Fluidized Sand Bed, this method simply suspends the fish poo, etc with some serious pumping action and lets the bacteria colonize the surface of these particles, adding lots more oxygen for the fish and nitrification. (I wouldn't wonder if the bacteria could even simply live suspended without colonizing poo bits (pb?), becoming suspended organic particles themselves).

It looks as though that is all good, but the pb builds up as it does not have the gravel growbeds, worms, etc that we use to deal with it, so they have a settling tank to reduce levels to something reasonable.

The nitrates build up too high at some times, so they also have detention ponds where pb etc can settle, create a permanent anoxic region, and break the nitrates into N2. Shame to lose the nitrates that plants would love, but we humans are dumping way too much into Biosphere I for anyone's good. (Another vote for closed systems! Here's to AP!)

HP, what are you using the term "pb" to mean?

i keep thinking you're saying LEAD

My Fluidized sand Bed was doing the biofloc thing, too. The sand was suspended in the lower part of the chamber, and the poo was a suspended layer above it.

Very interesting! Thanks for the link Thomas!

skim reading again Steve...you'll go blind

Not too far off: one often finds poo bits (pb) in the plumbum (pb).

Fascinating thread.

good to see you trawling through old threads chelle!

The problem I found with the filter is that it works great for 2-3 months, then a thick coating of sediment builds up on top of the sand/carbon mix which stopped any flow through the mix in the pipe...tried using stockings as a filter but this just prolonged the build up (and was cleaning woman's stockings on a weekly basis )

What if it was done with DD's idea EKB?



My interest is in the chelated iron. I think I read somewhere it is easily in short supply but if correctly supplied can even affect the taste of the fish positively - besides the obvious need in the plants. I have a real interest in alternates to commercial inputs if at all possible.

I think I would prefer to put this outside the bed and before the Fish Tank. Nitrates are to produce vegetative growth. Any excess after passing through the GBs becomes less desirable. Cleaner water for the fish... and I bet those bacteria offer much else we don't even suspect.

I haven't tried Dave's idea but re-reading it, I think it would also gather a lot of crap in it and thus need cleaning on a regular basis...this could be reduced by placing it before the water entering the FT as you suggested.

There has been a theory (put up by vb), that anaerobic areas exist in the GBs and help in balancing the system out by chomping on the NO3 - I am starting to think there is some merit in it but don't have any means of testing this

Yes. I would agree about there being anearobic areas within the GB.... in corners where sand etc has collected .. and then especially if the media used is a pebble with very uneven shapes... lots of nooks and crannies.

This would not help with iron chelation in any meaningful way though, would it? I am very keen to get that right..... believe it is possible... use an iron pipe for starters as suggested earlier in this thread. Place it where least solids can clog.... design it for ease of cleaning.... top of pipe on DDs design made into a lid?

Do you think there would be a chance of enough iron chelation occurring to warrant the effort?...

Also do a by-pass for when iron levels balanced.

What you think?

With you now C, I was wondering about the reference to iron before

The RSG filter was originally for reducing NO3 levels and I was mainly interested in that...the rusty nails was an after thought that Janet tossed in to see how it went.

I had uncovered steel rods in use with the door actuators and they lasted ~ a month before they rusted through and snapped (BYAP fish water is all powerful)...nails could be just thrown in anywhere and would then break down to help with the iron chelation levels without having to put it in an anaerobic area.

I bought a packet of chelated iron (powder form) and use that to regulate the amount of iron I put into my system.

Further to the steel rods - I covered them by sliding some 3mm air tube along the length and sealing each end with some silicone - once covered the rods have worked properly (haven't rusted through) for over 12 months now