Backyard Aquaponics
A place to discuss aquaponics

I have about 20 300g-400g trout at the moment feeding about 100-200g a day depending on the fish.

I have 1000l of media grow beds and a 500L tank for duckweed (i have just stopped the water into the duckweed tank).

I have 3 big zucchini plants, 1 huge snow pea plant, 1 big tomato plant and a few other smaller plants.

I have planted out some water melons and normal veggies but they dont seem to be growing?

Could the zucchini, tomato and the snow peas be taking all the nutrients?

I have 0/0/0 on the tests

Are the plants showing signs of nitrogen deficiency?

Keep in mind that if you transplanted stuff not too long ago, they usually take a few weeks getting their root systems back up to speed and we are in that phase of the moon where plants will be working more on the below ground growth so ya might just give it a little patience and maybe a cap full of seasol and see what happens in a couple more weeks.

And seeing as you say you just stopped the water going to the duckweed, you may see some increased nutrients here shortly, duckweed can be a huge ammonia sink.

The FT --> GB is via SLO at the bottom of the FT. The Duckweed outlet is near the top of the FT so i would have thought it wouldnt make a difference. I will wait for another week or 2 and see if its any better

I wouldn;t be concerned as yet, thats a fair amount of feed going in, how long have the new plants been in for?

Probably 2-3 week for transplants and probably for the same time that were seeded in the GB.

The seeds to seedlings are fine it is just things that were already pretty big not doing much

Watermelon and other squash-family plants have really tender feelings about their roots. In soil I never even weed around them, just pile on mulch to deprive weeds if they grow too close to the squash-roots.
Aquaponics makes a more forgiving environment for uprooting and replanting, but do know that squash / melons have sensitive feet and may take some time to get up to speed after any root excitement.
The seeded ones have had a head start. They have not had their "supporting community" around the roots disturbed either. There's stuff like mycorrhizae that grow near and around roots, we don't fully understand 'em yet, but they do some of the pre-chewing of nutes for the roots.

I would not worry or change anything because of what you're reporting.

Rick