Backyard Aquaponics
A place to discuss aquaponics

Dear,

Please see the attached pictures of my hydroponic system, is this an indicator of insufficient nutrient?

The last picture is of a tomato, is this a disease?

The pic of the speckled tomato leaf... I suspect is damage caused by Thrips or Mites... I would grab a magnifying glass or jewellers loop and have a look on the underside of the leaf.

Looking at the middle pic (the tomato) it may well be a Calcium deficiency. Is the newest growth deformed or "bubbly"?

The bottom pic (Capsicum/Chilli) may be a combination of two deficiencies, either Calcium and Magnesium, or Calcium and Potassium.

The yellowing between the veins on the larger older leaves suggests it's a toss up between either Magnesium or Potassium, just going on the pic I would say Magnesium, as Potassium deficiency usually manifests in yellowing (and ultimately necrosis) of the leaf tip and then margins, as well as the interveinal yellowing.

For Calcium and Magnesium deficiency you can use Dolomite lime. For Potassium deficiency you could use Potassium bicarbonate (sold in Australia as Eco-Fungicide). I would try the Dolomite lime first, wait a couple of weeks and see what transpires.

The Potassium bicarb should be added at 1/2 a teaspoon per 1000L. I have never added Dolomite to a system, but I understand it doesn't raise the pH as much as the Potassium bicarb, so maybe try 1/2 a teaspoon of it per 1000L as a starting point. Both will raise your pH if added to the system water, so if it is 7.0 or higher then I would just sprinkle a small amount of the Dolomite on the gravel around the affected plants as RupertofOZ suggests, and apply the Potassium bicarb as a foliar spray, as per the rate on the container.

If adding either to the system water, ensure you don't raise the water pH by more than 0.3 in any one 24hr period.

You also need to determine why you are getting these deficiencies. Calcium, Potassium and Magnesium will start to become less available at root zone temps under 20C... What is your water temp and what is your average daily ambient air temp at the moment?

They will also become unavailable at a pH outside of the ideal range... What is your system water pH?

Or you simply may not have enough nutrient inputs into your system for the plants you have. This can come about from:

1) Understocking with fish in ratio to the amount of grow bed/plants you have in the system.
2) Using a sub standard fish food.
3) Planting fruiting or heavy feeding plants in a newly established system.

Cheers!