Backyard Aquaponics
A place to discuss aquaponics

Good morning, we are building our first system and want to include flow beds, we are very aware of the need to filter out all solids and have designed a three stage swirl filter that works extremely well. I am a little concerned that it might take out a lot of the nutrients as well. Am I mistaken?

It will, especially trace elements and Potassium, but the collected solids can be put through a digester and the nutrients added back into the system... or used on wicking beds.

I haven't looked, but I'm sure there would be threads on here re digesters.

Why would a filter take out trace elements... and why Potassium in particular... :don't know:

I didn't say Potassium "in particular"... I said "especially trace elements and Potassium"... and I said that way because these are the elements frequently discussed as being deficient in AP, so I was suggesting that by removing the solids anthony would be removing those elements... but hey, if removing solids from the water doesn't remove nutrients from the system then he has nothing to worry about.

Thank you both for your input, we had thought about re-introducing the solids in some way or using them as worm food.
RupertofOz I was especially keen to get an answer from you as you have a proven flow bed system. I was kind of thinking a long the lines of, 'how could your flow beds work so well if the filter took out the nutrients' but I was looking for some re-assurance. If the nutrients are chemical components they become an integral part of the water and therefore can't be taken out by a filter. Am I right?

I'm interested in how you would add the 'digested' nutrients back into the system? Do they go on GB's or would you be able to somehow dissolve them and add them back...

I've read up a bit on what to do with the wastes - so far the easiest suggestion has been to aerate them (remove from filter bottom, add to bucket with an airstone, wait a couple of days) then use them on wicking beds or gardens, but I haven't seen anything about adding them back into the AP system itself. Sounds like something I would like to try.

@anthony - while trace elements have been discussed quite a bit on AP sites, what matters is that the ammonia gets through - that is the food for the plants. I've been running an IBC system for 8 months or so and have had not the slightest indication my plants are lacking anything - that might be because my solids end up in the GB and worms take care of them, but I've seen people with similar systems getting deficiency symptoms in their plants, so I am puzzled also.

Maybe 8 months isn't long enough, although the system was at least 2 years old when I bought it as is from a guy leaving town, or maybe the quality of fish food matters and some people buy cheap or generic food that doesn't have enough of the right chemicals in it?

If anyone else knows of where we might get answers to this kind of thing I'd love a link.

Wouldn't the addition of a bead/sand/moving media bio-filter help solve the "problem" of solids and assist with the physical breakdown, as well as early aerobic digestion, of waste?

I have a friend who has been using compost tea and spraying the net pots here and there to help them along and from what he has said everything has been way better because of it. I was planning on doing the same thing.

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This is what I have been talking about in my thread with a three stage filtering system (swirl/"sponge"/bead) I think if you go with something like this I don't think you will have many issues. But I can be wrong I am a newbie

Here's what I tried (and it works): Once the waste has been in the digester with air for a few days, switch the air off for about 12 hours (overnight) and allow the solids to settle. Siphon the clean, nutrient-rich water from the top of the digester tank back into the AP system through the fine material filter. When you reach the solid material slurry at the bottom of the digester tank, siphon this off into a separate container for dispersal on the dirt garden (citrus trees love it, but be careful with some other plants as it is very rich and some other fruit/vege plants don't take too kindly to it unless it's well diluted). Now with the empty digester, add the "new" solids from your filters, top up with system water and crank the air; repeat EVERY two-three days.

Thanks Bunson

RupertofOz your link doesn't work

Thanks bunson - exactly what I needed. Mind you, between that and my worm farm tea I could be enriching most of the street...