Backyard Aquaponics
A place to discuss aquaponics

I have a fairly new growbed going (about three months old) and am emptying a small outdoor fish pond. I was going to give the two inches of fish solids at the bottom of the outdoor tank to my worms but wondered if I would do better to put them directly into the growbed. Would that waste provide the minerals that have not yet had time to build up in the system or just add sludge and anaerobic spots in the gravel?

Are the minerals, etc. in worm tea accessible to the plants in an aquaponics system and if so, are they any better/worse than fish waste? I remember discussions on the hydroponics forums in which the consensus seemed to be that compost tea nutrients were not able to be taken up by the plants in those systems. Is worm tea different than compost tea in this way? Worm tea does wonders with our potted plants, should I expect the same in an aquaponics system?

Does worm tea change the balance of the water in any way? Does it have any impact on the fish?

Thanks.

Not sure about the worm tea... was aware of problems with compost tea... and I believe worm tea as well ... in hydroponics

But my biggest concern would be the 2 inchs of fish waste.... that's a lot of sludge...

And IMO almost certainly anaerobic.... I think if you stirred it up and/or put it on your growbeds.... you'd suck the oxygen and life from them....

I'd compost it... but probably in small amounts... maybe the worms could cope... but I'd be worried it would suffocate them as well, by robbing all the oxygen....

Got a green waste pile???.....

If it is the muck from the bottom of a well balanced ornamental pond, then it probably isn't as nasty as all that. If it is 2" of food and poo build up in a more heavily stocked AP system, then you probably have some major problems.

Be carefull when adding anything that wet into a worm bin as you will be adding way too much water. Make sure you have lots and lots of dry shredded cardboard to help absorb that excess moisture or your worm bin will become a wet nasty anaerobic thing that could turn anyone off worm bins.

If the sludge is from a well balanced nice ornamental pond, it would be ok to mix some of it into your grow beds. If it is a really nasty sludge of poo and fish food in a badly overstocked pond, then you probably don't want to put too much into your grow beds.

When people talk of using worm tea for their gardens or ap systems it should be noted that there are two very different versions of worm tea.

The proper version of worm tea used very finished worm castings that are then soaked in aerated water for a day or three perhaps with some extra sugar or molasis for bacteria food if soaking for more than a day. This is then strained and used straight or diluted for spraying on plants. This is the real worm tea.

The other version is really just the leachate from an over wet worm bin. The composting is not necessarily complete and this version of worm tea may or may not be good for your plants or system depending on how anaerobic the bin is, what sort of decomposition is going on in the bin, the materials in the bin, etc. Since there are so many variables, this sort of worm leachate is not really recommended. To get enough of such leachate, the bin needs to have a large amount of water put through it which usually means it is too wet and either is or will quickly become anaerobic.

I have in the past (when starting my new grow beds) put a hand full of nice finished worm castings into the beds along with some worms to get the population started in my grow beds. I can't be certain that it helped mature the beds quicker but I personally think it did.

Good points TCL...

+1

Thanks TCLynx. The solids are from the former, a balanced koi pond into which very little food, in the way of pellets, etc. was added over the summer.

I have used the solids in my worm beds before and the worms seem to really like it.

It seems best to try the worm tea. This is actual tea as you described it (without the molasses or sweetner), created from digested castings and aerated for a day. What Rupert said makes sense in terms of possibly creating anaerobic spots in the bed. When I have added these solids to my garden, it takes a while for them to breakdown and become soil.

Thanks for your responses.