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Hi All,

I had few questions. I started two aquaponics systems. one is 5 weeks old and one 8 weeks old. The one 8 weeks old had a consistent PH of 7 throughout. I planted basil,Lettuce, peppers,beans,sweet peas,mint,eggplant and tomatoes. I have 50 gallon tank with about 12 rainbow trout. two growbeds 2' x1'x 6" . Lettuce did really well and i already harvested a few. basil did well too. snow peas and beans are flowering as well as producing pods. the eggplant and pepper are a little slow but reaching there but my tomato plants keep dying. I planted another batch three weeks ago but same problem, they start good but after about ten days the new leaves start turning yellow and then the growth slows down and then the older leaves turn yellow and whole plant becomes white except the stem that stays green. I added chelated iron but nothing happened. My flood cycle is 11 mins to flood and 1 min to drain. My questions are:

1. Do you think it is happening because my growbed is not mature ?
2. Or my Growbed not deep enough
3. May be because of the water being cold as it is 15C ( i don't know if tomatoes like warm water)
4. Or My flood and drain cycle being too quick
5. Or is it Damping off disease
6. Or is it some kind of nutrient deficiency

Any help would be greatly appreciated as i planted about 20 of them and all ended up with the same fate. Thank you

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Hey MoeCanada, welcome to Aquaponic Gardening! It's nice to see another Canadian find us here.

I'm thinking you must have pretty decent light because your peppers are doing well, but what kind of light do you have?

I think you might be looking at both 3 and 5. From my experience tomatoes don't like cool, and when they're not happy they're susceptible to disease. If it's damping off they usually fall over though. It could be some other fungal disease. What's the room temperature?
What do your other water tests show?

New leaves turning yellow first (especially if the veins stay green a bit longer) usually means iron deficiency but there are other things that could be missing. For a new system a few good doses of seasol or Original Maxicrop can help with most other deficiencies.

Damping off usually takes seedlings before they have more than 4 true leaves and the plant stem simply shrivels at the soil line and it falls over before the leaves die.

I would guess the problem is probably a combination of 1, 3, and 6 though if all the other plants are doing fine, it may be more to do with the temperature.

I would recommend a deeper grow bed but I don't think the shallow grow bed is causing you issues yet, that will probably come later if you start pushing the system stocking much, you might struggle with root and solids clogging the grow beds some.

Oh, and lighting is pretty important to tomatoes as well.
Hi Everyone,

Thank you for replying. They are under t5 flourscent 120HVAC 60watts light. I have about four of them on top of the growbed. The room temperature is 19C as they are in the basement of my house. Outside temperature (-10c).

PH: 7
Ammonia: 0.5
Nitrite: 0.8
Nitrate: 20ppm
In my experience, florescent lights need to be an inch or two from the leaves of the plants to be very effective. (This is difficult with plants like peas, tomatoes, beans, peppers etc.) I used the florescent fixtures over lettuce ok but didn't work well for me with much else.


MoeCanada said:
Hi Everyone,

Thank you for replying. They are under t5 flourscent 120HVAC 60watts light. I have about four of them on top of the growbed. The room temperature is 19C as they are in the basement of my house. Outside temperature (-10c).

PH: 7
Ammonia: 0.5
Nitrite: 0.8
Nitrate: 20ppm


Kobus Jooste said:
While your temperature is still a bit low, I want to think that you could have the same issues as I have seen. I have a youngish (1 year) micro system that has 5 cherry tomatoes in it among others. It was doing well up to a point in terms of nutrients, but the tomatoes take terrible strain when the nitrogen (and I suppose other micro and macro nutrients) start running low. Them and secondly the cucumbers in my system showed yellowing of leaves while the other plants just slowed down, but still looked good. I have read many times that people advised putting tomatoes into a system at a later stage as it needs to build up sufficient nutrients first. Not sure when they SHOULD go in, but for me, they are the first to complain! If you look at my photos you will see the lay-out. Everything still looks pretty much the same apart from the tomatoes that look like they are being starved - hardly a leaf left, all yellow and dying off.

Hi Kobus,

I think my problem is same as yours. How did you manage to grow them in the end. was it just time or you did something else. Thanks
Just wanted to post this info, http://en.wikipedia.org/wiki/Tomato, it may not be an issue with most on this site but i had to learn the hard way. After two successive attempts and failures at growing tomatoes, I've learned to avoid smoking and to wash hands properly before handling both pepper and tomato plants.

MoeCanada said:


Kobus Jooste said:
While your temperature is still a bit low, I want to think that you could have the same issues as I have seen. I have a youngish (1 year) micro system that has 5 cherry tomatoes in it among others. It was doing well up to a point in terms of nutrients, but the tomatoes take terrible strain when the nitrogen (and I suppose other micro and macro nutrients) start running low. Them and secondly the cucumbers in my system showed yellowing of leaves while the other plants just slowed down, but still looked good. I have read many times that people advised putting tomatoes into a system at a later stage as it needs to build up sufficient nutrients first. Not sure when they SHOULD go in, but for me, they are the first to complain! If you look at my photos you will see the lay-out. Everything still looks pretty much the same apart from the tomatoes that look like they are being starved - hardly a leaf left, all yellow and dying off.

Hi Kobus,

I think my problem is same as yours. How did you manage to grow them in the end. was it just time or you did something else. Thanks
I've tend to agree with TCLynx on 1. My young AP grew cucumber,lettuce,bok choy,and chives very well at start-up. The broccoli, tomatoes,and peppers started showing better growth after about 3 months and this only when i supplemented with some micro nutrients.Kobus and TCLynx can share what and how much of these can be added safely for tomatoes. In AP nutrient requirements differ from plant to plant. As backyard AP'ers we tend to stock a variety in the same bed. Kobus inoculates with nutrient at the root site and still others utilize other methods like foliar spraying etc.
I tend to put a heaping table spoon of chelated iron powder in each of my grow beds each month (my pH is high and my well water deficient in Iron) I also sometimes put about a quart of Maxicrop original into my big system, just a splash in each grow bed where the water enters. That is enough Maxicrop to turn my water brown for a few days. The Iron tends to turn the water orange and my system water is usually a nice yellow color.
I think the appropriate nutrient dose of individual plants has been a "Grey Area" in the AP information available so far.This is an important area since backyard'ers will naturally tend to place huge demand from their budding systems by virtue of planting a variety of plants early on. If we know the individual needs of each plant we might be able to at least foliar spray on an individual basis. So far I've found very limited info on this subject.
Three cucumbers, 12 strawberries, 5 tomatoes, 3 corns, 2 kale, 2 butternut, a pile of spring onion and water cress, cut flowers, spinach, parsley, lettuce................................................
And how much Tilapia?.........probably 100? because you might need that amount. Sounds like it's commercial....no wonder you're nutrient deficient!

Kobus Jooste said:
I use a South African product, which would not help explaining in detail here other than I have dropped enough of it to turn my water quite tea coloured. My system is already a year old, thus not as "young as others, but I still managed to drop Nitrates from 30 mg/L to 1.5 in a matter of weeks. Three cucumbers, 12 strawberries, 5 tomatoes, 3 corns, 2 kale, 2 butternut, a pile of spring onion and water cress, cut flowers, spinach, parsley, lettuce................................................

TCLynx said:
I tend to put a heaping table spoon of chelated iron powder in each of my grow beds each month (my pH is high and my well water deficient in Iron) I also sometimes put about a quart of Maxicrop original into my big system, just a splash in each grow bed where the water enters. That is enough Maxicrop to turn my water brown for a few days. The Iron tends to turn the water orange and my system water is usually a nice yellow color.
Unless you have some means to measure the nutrient availability of all the different nutrients in the system and can then compare with what the "optimal" amount of each would be, I'm not sure how knowing what the optimal nutrient levels for each individual type of plant is really going to help a backyard system.

There has been lots of research into nutrient mixes and different "optimal" levels of nutrients for different types of plants for hydroponics. Again, knowing what levels might be good for different types of plants doesn't help much if you can't tell what your exact mix is in order to figure out the difference to make it up.
This is one of the reasons that hydroponics has to dump and replace their nutrient solutions, because they get out of balance and it is far easier for most to simply replace it rather than trying to figure out the exact levels of the different nutrients in order to add only the right amounts of things in order to re-balance.

Harold Sukhbir said:
I think the appropriate nutrient dose of individual plants has been a "Grey Area" in the AP information available so far.This is an important area since backyard'ers will naturally tend to place huge demand from their budding systems by virtue of planting a variety of plants early on. If we know the individual needs of each plant we might be able to at least foliar spray on an individual basis. So far I've found very limited info on this subject.
Was thinking more along the lines of foliar spraying.If we see plants flowering or fruiting we can leaf spray with potassium to that individual plant as the other plants won't have this requirement. If we add it to system water we may affect the other plants uptake of nutrients other than potassium. So too, some plants require more iron at certain times than others as well as other micro nutrients. This way we can lend to the varying needs of individual plants.

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