Backyard Aquaponics
A place to discuss aquaponics

Although my system is running well my plant growth has dropped way off and there is VERY little flowering except for my beans. I have tomatoes that are getting big bu NO flowering at all. I've been adding 1tsp iron to the system for about 2 months to try to green things up but it doesn't seem to be working. My basil has never had good color although it grows well. It has all the signs of lack of iron that I've read about. Even my lemongrass has gotten yellow.

Here are my readings. They've been stable for months now:

water temp: 85F, 29.5C
PH: 7.6 and somedays a little higher
Ammonia: .25
Nitrites: 0.0
Nitrates: 40

My system cycles about every 15 minutes. All the flows look good. fish are pretty happy although some days they eat better than others.

Any help is appreciated.

Jazz,,,yep PH 7.6 is not ideal for most plants.Foliar spraying is probably the best way around your plant problems,,,make sure it's a fish safe product,,,seasol is good.
As your system ages,PH should drop and if it get's closer to 7.0,you'll find your plants are more easily able to get the nutrients out from the water and then you can just dose the tank rather than foliar spray.

Potassium?

More likely pottasium,iron,copper etc,,,they are less available at high PH.

OOOPS,,wrote Potassium,,meant Phosphorus

Do the plants get enough sunlight?

What do you have for growbed media? Do you use anything to keep your pH at that level? I thought I'd read that too much calcium (from too much shell grit or other sources) could inhibit plant uptake of other nutrients, could be wrong though.

If you think it's a potassium deficiency, you could try burying a banana in the growbed. pH 7,6 should be fine, but you might find that your plants do better (better nutrient uptake) at a lower pH like Chappo said.


If the above doesn't give any answers, try another fish diet - maybe there just aren't enough trace elements in the system?


That's all I can think of, hope that helps. In any case, good luck and keep us posted!

My green beans were not doing well so I sprayed them with iron which helped, but they continue to struggle I think due to their location right under the irrigation grid holes. I think they are too wet there. Do your plants have a chance to dry out a bit, and is the water level a bit below the gravel surface so that there is some non-wet gravel for them? Pulled a couple plants recently and sometimes they don't have a very developed root system, looked kind of loaded down with sludge. Can you pull one of the less healthy plants and post a picture of the roots?

I would say potassium or another elemtn. My peas were not doing as well as I thought they should, so I put HEAPS of seasol into the 8000 liter system, and now they are putting out huge pods full of peas.

Fish food just doesnt have all the nutrients required for optimul plant growth.

I haven't used any yet... but that was before. I will today with the new plantings I have planned!

I can't find Seasol here in the US. Does anyone know if it's sold under a different name?

http://www.maxicrop.com/pages/products_1_iron.html

Mark,
I'm having similar problems with many plants not liking the pH so much and having difficulty with iron uptake. I've been using the regular garden Iron Sulfate to do foiliar spraying when I have time (problem is ya don't want to spray anything in the heat of the day there.) I'm hoping that with more maturity, the system will be better able to support the plants even with the high pH but only time will tell.

My tomatoes have been doing great though, I suspect the lack of flowering in yours may be heat related. I've heard that tomatoes have trouble setting flowers during the summer heat down there, as the weather cools off, you may have better luck with that.

Anyway, the toms don't seem to mind the higher pH though I've had little/no luck with any plants in the cucumber group. The really don't seem to deal with the high pH well and show major signs of iron def. I've noticed the beans in my system are really struggling too and Okra as been sad also.

You can get Flourish tabs or Pond Flourish from Aquatic Eco Systems or probably other places which has fish safe amounts of micro nutrients but it is $$ and a bottle won't last long. I've used it but I can't really justify buying more of it. Lately I've been using The Iron Sulfate and adding a little Potassium Chloride (I did the banana thing a while back too.) I was thinking of trying to get some green sand as it is supposed to be a good source of Iron and Potassium so it might be worth sprinkling that through my beds.

Whats wrong with the maxicrop?

OBO, The maxicrop looks good to me. I'm going to buy a small one to test but hopefully that will make the difference.

It will