Backyard Aquaponics
A place to discuss aquaponics

Hi all....new to forum and aquaponics and in process of setting up system. I am concerned that the system will not supply enough nutrients to maximize growth of things like tomatoes, eggplant ,melons ect. I would like add organic nutrients like kelp/fish emulsion and worm tea............is that going to cause my fish problems(tilapia)? Also I read about a system (growingpower.org) that has the gravel beds for greens but puts their heavier feeding plants in pots with coir and compost in the gravel beds as well. This seems like a good solution to get those babies growing big............what do you guys think?

Hmmm,
check my thread and see if you think you need nutrients over and above fish poo
Right click and open a new tab on the veiw topic below

I have dug pots with compost down into my "nursery bed" to start plants for the dirt garden and such so a little bit of compost having contact with system water should be ok as long as the compost if pretty safe stuff. At least based on my system and the compost I have put in trays and pots into my system, it is pretty safe. If you are running a small system it would probably be questionable to go adding too much extra as it is easy to spike a small system and throw things out of whack.

As far as needing to do it for heavy feeder plants, not really needed once the system has some time to mature. Actually, tomatoes may tend to rot if planted in something that holds as much water as compost or coir. Many people have found that in Aquaponics with flood and drain media beds as the "filtration" suddenly Aquaponics is able to support flowering and fruiting plants. About all the additives people sometimes seem to need are seasol or maxicrop to supplement the potassium (this helps flowering/fruiting plants in AP since the fish food/poo supplies plenty of nitrogen and phosphorus) and where the water doesn't have sufficient iron, chleated iron is sometimes added to systems.

So yes to the kelp that is a good source of potassium and trace minerals/nutrients.
No to the fish emulsion, it would add too much nitrogen which is already being supplied by the fish feed/poo from your live fish.
Worm tea, I suppose if you want to use it you could spray it on your plants but a better method of getting the good from the worms is to add some worms and castings into your grow beds. The worms will help process the solids in the grow beds and the castings (a few hand fulls when starting up the system is all) can help get the bacteria population up and running in good order. And yes, worms live quite happily in flood and drain gravel beds.

Not from waht I could see on their site... the tomato gravel beds would appear to be a seperate run to waste "Bengal" type system... more "hydroponics" than "aquaponics....

Not a bad idea as such... but still run to waste and not recirculating... would require a good, constant water availability...

I've got/had absolutely no problems growing tomatoes in "flood & drain" media growbeds... neither have others...

OK... I take that back...the top run of growbeds does appear to have tomatoes in pots...

possibly filled with coir... presumabely just sitting in running water and "wicking" up into the plants....

Sort of continuous flow....

Cheap and easy... and workable I suppose... but I don't see the benefit against flood & drain.... in terms of growth... or nitrifcation....

Other than intermittant "drip feed"... or "wicking".... coco-coir is generally just too wet for most AP systems....

thanks for the input.......I am relieved to hear all that. We are in a water rationing area and I definitely would not add anything to the water that could not go back in the fish tank. You have saved me some time and uneccessary labor. BTW Seasol is not availble in the states and I have heard many of you aussies raving about it for your aquaponic systems ......anyone know if maxicrop is similar and as good ?

Maxicrop is similar... as are any "kelp" extracts....

And ditto to TCL's comments about adding "worm tea".... worm castings are fine...

Flood and drain gravel beds are definitely the way to go for growing tomatoes in a backyard scale AP system. Tomatoes grew great in mine and I can't grow tomatoes very well in ground here as the nematodes are rampant.

Yes, I use maxicrop.

Which Maxicrop. I see one made from seaweed and another thats made from fish emulsions.

Seaweed

I don't think a pot with compost would be a problem to the system, maybe only the bottom of the pot should get wet. Compost would probably help increase the biodiversity in the beds too (I added some to the gravel on a lark).

I purposely grew only fruiting plants last Summer, other than making sure there was enough iron, calcium, and potassium things grew fine with just AP water. The only thing I had trouble growing last year were beans for some reason.

viewtopic.php?p=148719#p148719

You guys know that my system is 'flood' don't you...
as in always 24/7
Not everyone uses additives

What is the difference between kelp and kelp extract? I

The "kelp extract"... is extracted from the "kelp"....

Seriously... it's probably just dried/crushed... then reconstituted into solution...

You want the maxi-crop that is like 0.1-0-1 It is the seaweed extract. There are several types of box maxi-crop and seasol. For aquaponics we want the plain one with no added fish emulsion or extra nitrogen fertilizer. However there is a Maxi-crop plus Iron which might be good to use if Iron deficiency is a problem in your system.

some one not so long ago added kelp meal to their system and had some problems. Kelp meal has more nitrogen in it and the solids need to break down to deliver the nutrients. This whole process seems to put a really heavy load on a system so I would advise making a "tea" out of kelp or kelp meal instead of dumping it direct into a system.