Backyard Aquaponics
A place to discuss aquaponics

I've attempted to use a swirl filter before. I expect I might have been more successful with it had I been using it to feed a duckweed bed a slow flow. I found it didn't work very well at higher flow rates. Also, fish poo from fish being fed floating fish food, floats more and doesn't separate out as well.

But anyway, even though it didn't work all that well for my purpose, that swirl filter I tried out, did need to be cleaned out about every other day. If I did it every second day or less often, it was nasty enough to make me gag and not many things do that to me.

Perhaps solids removal is appropriate for commercial raft operations that have employees scheduled to clean out and do the maintenance daily but in a backyard system where people might go on holiday or take a long weekend, that kind of daily operation I personally believe is best avoided. (I do use automatic feeders and the neighbors check on things daily but about all I ask of them is to fill a feeder if empty and call if anything else seems dodgy or they see floating fish.)

I'm sure one could work out a system with a settling tank in which solids settle and are sucked (once a day?) into the growbed and the clear liquid goes into a duckweed bed. I've also considered a system with a normal flow where tilapia are under a screen and duckweed above it and solids and water are pumped into a growbed (with whatever N remains). One could even have a small area of the duckweed unprotected by screen as sort of an open salad bar for the tilapia.

We know that the standard rule of thumb is pretty darned fail-safe, but it sure is fun to try different ideas. Keep 'em coming!

Absolutely... and indeed I employ both a settling tank, and a tidal duckweed tank in my blue barrel system...

Here's an early shot...



The bins are interconnected at the bottom... the front bin is stocked with yabbies, and normally fed by an overflow from the quarantine/holding tank... and allows a lot of fine sediment to drop out due to low/slow flow...

The back bin is also (sometimes) stocked with yabbies... and is tidal... and utilised to grow duckweed...

Thought I had a recent photo... but can't find it... will post one tomorrow...

There's nothing wrong with running add-ons for extra bio-filtration.. and/or solids removal....

And they're probably both necessary if you want to increase stocking density... indeed I also run (as a backup on a seperate power circuit/battery backup)... small filter boxes on my systems for that reason...

But I think they're exactly that add-ons, rather than substitutes... exceptn for UVI style systems...and the discussion was regarding flood & drain growbeds...

What ever anyone wants to do regarding their systems is their business... IMO the main fish tank should be kept clear of gravel/plants etc... they serve no real beneficial purpose IMO.... and can easily/quickly become problematic....

Exactly, plenty of other places in a system to put add ons. I do like a settling tank, I have had good luck using corrugated fiberglass sheets angled up into the water flow, then goes from there into the sump or other filter. Its easy to flush out and removes a lot of solids.

The only main tanks I'd have anything other then fish in is breeder tanks and thats a specialized tank for some species only. Trout brood fish do well alone , no furniture or plants. Tilapia, perciformes, I like big flower pots for each to have their own territory, but they are the exception.

im new, but in my experience with hydro veggies ive expanded my grow beds and area without upsizing my water levels by rotating which beds get water with timers from the same tank, im assuming this would lend itself to aquaponics as well.

This is exactly what we do with the Aquaponics Valves (special indexing valves for Aquaponics) One can easily manage a 2:1 ratio of grow beds to fish tank using one of these valves (provided that each grow bed is smaller than the fish tank) without needing a sump tank.

Now expanding the number of grow beds can probably only go so far. Like if you had a 300 gallon fish tank and only stocked at reasonable levels so as not to have to panic if the power goes out for an hour here or there. Anyway, a reasonable number of fish in a tank is only going to supply enough nutrients for so many plants so say a 300 gallon fish tank might easily support 600 gallons of grow bed and the plants via sequencing, if you were to up that to say 1200 or 1800 gallons worth of grow bed and plants, the nutrients might not be able to keep all the plants in heavily planted beds happy. And you are probably not going to manage double the reasonable stocking density in the 300 gallon tank without some extraordinary measures.

The 2:1 ratio makes for a nice sturdy/stable system. If stocking heavily and feeding lots with good weather, I could see a 3:1 system perhaps keeping plants happy but I fear beyond that, it might be better to increase fish tank to go with the increased grow bed.

Anyone care to elaborate on the "tidal" and "settling" tanks? Trying to wrap my head around that.

Ok so no gravel or plants down in the FT, but how about a small styrofoam floating raft in the FT? They have those floatie thingies that BYAP has that fill with hydroton that are the same thing aren't they?

The floating pot with clay in it is good to give the plants roots some growing area where the fish can't attack the roots (if you are growing fish that eat plant roots)..

Foam works really well so long as your fish don't destroy the roots.... You can make a cage under the floating raft to protect the roots if need be.

the "tidal" tank will have a fluctuating depth,,

the "settling" tank is the first tank the water is pumped to, and solids have a tendency to settle there since there is a standpipe drawing the water off from the surface

Yes every system is different and the media also plays a part if you are using expanded clay pebbles( way more room for bacteria) or gravel I have 10,000 of fish tanks 10,000 ltrs of growbeds/flow ponds and a 10,000 ltr sump tank I only have 3 pallets of expanded clay being 165 bags @ 45 ltrs equals roughly 7500 ltrs of GB media ....I have 550 Jade perch being minimum 250mm long 11 mths old and over 3000 feeder fish up to 3.5 inches long and the Expanded clay copes with this quite easy even being way under the 1: .75 even depending on if you just use the actual fish anks or the whole water capacity...

With bucket loads of worms in it also they are eating the decaying vegetation and fish wastes and excess food that gets sucked through.... So if using Gravel I reckon I would need a heap more growbeds to do the same job....

Double Decker,
I think a huge part of the reason for needing a fairly large amount of media for flood and drain media filled grow beds is more to do with solids handling capacity than the bio-filtration capacity. As in, the mineralization space required in a system that retains all it's solids needs more media space than just the bio-filtration requirement.

So just because the clay balls provide more surface area than many types of gravel, it doesn't necessarily mean that you can get away with less media beds long term by using the clay balls unless you are removing some amount of the solids or cleaning the grow beds periodically.

But, as we have all seen, there are many ways of doing things.

Like Murray's CHOP II system where essentially he has been letting the fish tank drain into the sump tank and pumping from the sump tank to the grow beds and fish tank. This is essentially allowing the sump tank to act as a settling tank. Some of the solids get pumped to the grow beds or back through the fish tank and if they build up too much in the sump tank they can be sucked out.

Issue I see with settling tanks, swirl filters, clairifiers is that they are an extra tank that takes up space (and the more flow you want, the more space they take to be effective) well unless we are talking industrial size facilities, I would rather just have grow beds handle it all since they take care of all the filtration functions plus growing the plants without requiring additional aeration for their proper functioning.

Hi,
Another thing to take into account is water capacity.For example if you have half a 55gallon barrel as your growbed or filter, fill it with water to the overflow and for a figure we will say you have 20 gallons,now fill it with your media if you are using it as a filter you could use filter matt fill it with water and you could have up to 15gallons of water in the tank.Now fill it with gravel and you may only have 5 gallons so your filtering capacity is reduced needing more beds.Retention time is also important for adequate filtration.

dasboot,
I'm not sure I would rate the filtering capacity by the amount of water that can fit in the filter at any one time. It will be more closely related to flow through and water contact with media surfaces.

Seeing as media filled grow beds serve all the filtration functions in one container without additional maintenance, they get a big vote from be for ease and efficiency.

For example, one might be able to handle all the solids of a system using a pair of barrels, but then they need to remove solids from the first barrel daily and then regularly clean out the net tank, that really only takes care of the solids removal and requires regular work. There is still a need for more bio-filtration and plants to use up nitrates. One might be able to add another barrel to handle the bio-filtration. and then raft beds for the plant space. Seems to me that the same volume of all that could be used for media beds to get the same result without requiring daily removal of solids.

Of course, which method is chosen will depend on the goals and situation for the aquaponics system. Some one who wishes to grow lots of fish and doesn't want any veggies will probably remove solids to reduce the amount of nitrogen left in the system to be dealt with but if one wants to grow all the veggies for a family and isn't that interested in eating the fish, leaving the solids in will provide more nutrients for the plants while allowing them to spend less money on fish food.