Backyard Aquaponics
A place to discuss aquaponics

I went to Friendly Aquaponics (near Honokaa, Hawaii) Saturday. Very impressive.

One of their systems was a "backyard" system consisting of a 1500 gallon understocked FT and two raft grow beds. No clarifier or other filtration. When I asked to compare it with flood and drain they said the biggest problem with flood and drain was the need to periodically clean the media--a big and messy job.

So, for those of you who have had systems up and running for years, any need to clean the media? If so, can it be done in stages? Or is this drawback a straw man?

Jerry

Straw man... Jerry... it's an old "furphy" IMO...

A properly designed flood & drain system... stocked and fed at suggested rates... doesn't need cleaning...

Overload the growbed... through overfeeding... or overstocking... then yeah...

Just like any other filter system... if you overload it... exceed it's filtration capcity... then you'll have to do maintenance...

That's why commercial filters usually require regular backwashing.... because they're being pushed beyond their capacity to process feed waste... either because of over-feeding... or over-stocking...

And because, unlike a flood & drain growbed stocked with compost worms... they don't have the ability to deal with the solid wastes...

I have been running 3 years and never cleaned a grow bed yet and there ant nothen wrong with the growth in my system

I have dismantled a few smaller growbeds which have run for 2 to 3 years (one for just over 3 years) and I found very little in the way of waste or "muck" - there were a few very healthy and happy earthworms and a little muck - but beds were FAR from needing to be cleaned...RupertofOZ is right - balanced systems run at suggested ratios etc will result in happy growbeds...

I'm yet to clean any gb's. I do have a few with fine gravel so I expect them to be first. But have been running then as constant flow with 500 ish fish and they still look clean.

Has anyone cleaned a GB.?

100% agree....

i have little cleaners in my grow beds, they have been working a treat! but i have warned them that if they don't do there job 'there fish food!'

Most of my GBs are filled with finer gravel now and no real build up either...

Just keep chanting these words
"stocked and fee d at suggested rates"

My growbeds are getting cleaned constantly-------But luckily I don't have to do it------and I'm not paying anybody to do it-------The worms seem very happy to work for fish poop.

5 gallons of flood and drain gravel will handle the waste from one pound of fish without any periodic cleaning (other than compost worms) in my experience but I've only been doing this for a year and a half.

A bonus is that the worms will not only munch the fish poop, they will also breakdown the old plant roots and other organic material left in the beds.

Gotta love recycling

I always smile when I'm working in the grow beds and see lots of worms going about their business.

I cleaned my continuous flow growbed once in about 6 to 8 years. It's fairly clogged up but I'm not going to clean it, seems to have reached an equilibrium.

Flood and drain system must be about 5 years old now and never been cleaned..

I'd like to note that tilapia are really trough fish that seem to survive just fine in some of the most terrible conditions. I don't think a filterless system such as you describe would work at all with other types of fish. On that note, I expect that if there are system out there terribly underfiltered where people are having to clean the grow beds, they are probably systems with tilapia in them (otherwise they were shut down due to other types of fish not surviving such under filtered conditions.)

It was friendlies that talked about removing some rafts from their system to slow down the ammonia conversion during cycling because the nitrites were at 10 ppm for so long. So basically they used sun light to hinder the ammonia conversion for a while to let the nitrites catch up. This is a sign of how tough the tilapia are!!!!!!!!!!

Just because they can survive such poor conditions, doesn't mean we should subject them to it. Please make sure your system provide enough filtration for nice water quality even if your fish could survive worse. Remember, you are planning on eating those fish, do you really want them steeped in their own poo for their entire lives?

I've got to admit.... I'm at a complete loss to understand the rationale behind such a suggestion....

If the system was "new" and "uncycled" .... and ammonia very high.... then by definition the "nitrification" conversion to nitrates would be inhibited by the ammonia level...

And represent an imbalance... probably because they were stocking, and/or feeding at a level that exceeded their filtration capacity at the time....

Or their temperatures were too cold... and from memory I think this might have been the case... or the extra warmth from the sun... heated the water, enabling the cycling process...

They would have been better off, and acheived the same cycling time... by removing stock.. and/or cutting their feed rate....

And apart from which, a nitrate reading of 10 was inconsequential anyway...

Another thing I've noticed, and it'll probably be an unpopular notion.... is that continuous flow systems... or systems that employ continous flow trickle tower filtration....

Hold the nitrite spike for very long times.... again IMO... a sign of imbalance within the system... and probably a sign of under-filtration...

My intial perch system was under-filtered for the number of fish stocked and feed rate... running an overflow standpipe virtually non-stop... a "continuous flow"

So I added a trickle tower in an effort to provide more filtration and to speed the cycling process...

The result was absolutely nil... nitrites remained high, nitrates low... and that was in late spring when temperatures should have been nearing optimum...

I removed the trickle tower, and converted the growbed to a timer based "flood & drain".... and the system cycled within a week...