Nitrogen supplementation

[mtnester]

Hi
I just cleared out remainder of a batch of about 40 rainbow trout from 5m3 tank and replaced with 100 x 25mm barramundi. Meanwhile I had a good crop of veg in 12m2 of beds that have suddenly run out of nutrient, I guess. Leafy things seem to be struggling all of a sudden. We had a few very hot windy days in Perth that don't help but I suspect nitrate is gone too. Any ideas how to keep this up without harming barra Could I use urea to avoid salts build-up or would this harm the fish
Tony

[Dufflight]

Urea can be used in small amounts and give it a while to work. I wouldn't add it over a long period due to some metal content. Pee is another interm source. And a bit of seasol always picks the plants and the fish up.

[GaryD]

Hi mtnester,

I'm not entirely clear on how your system is configured. Can you describe it or point to a photo of it?

I advocate for fishless cycling, and I've used and recommended urea in the past, but I wouldn't recommend its use in tanks with live fish in them.

Are you able to easily disconnect your grow beds from the fish tank? Is it possible for you to feed the grow beds independently of the fish tank while you strive to balance the needs of your fish and plants.

I wouldn't put anything in with the fish......they might only be tiny at this stage but they'll start pumping out their own ammonia soon enough and in this weather they should be feeding hard, too.

If I had to choose between the fish and the plants, it's the fish for me.

Having said that, I design my systems so that the growing systems can be disconnected.....for exactly this sort of situation. It offers you more options when you need to boost nutrients......or deal with an infestation or a disease.

Of course, you'll need a trickling bio-filter in there somewhere.....so that you can continue the nitrification and aeration (for your fish' sake) while your growing system is offline.

If, by chance, I've misunderstood your situation, feel free to ignore everything I've said.


Gary