Flood and Drain Cycle and Tomato Growth

[MoeCanada]

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

[Harold Sukhbir]

Proportionally beds offer much more nitrification surface area than rafts. Friendly's recommend .3lbs fish/sq ft.raft.Most rafters grow leafy plants ( lends to commercial, fast growing lower nutrient demands), they tend to avoid crop like tomatoes, not that they can't grow in rafts, but roots create anaerobic problems and other compatibility and maintenance issues. Looks like over-planting due to "Farmer's Exuberance" to me! Haaaaaa!

Kobus Jooste said:

Told you I'm into pushing the system. Actually it is 40 tilapia. I have some communications from a place that does low density AP that stated that they consider the lower limit of fish weight to bed area ratio to be 450 grams of fish per meter square of raft. Well I've got around 10 kg's of fish max and 4 m2 of gravel bed (over 2 kg's per m2). Somewhere things are not adding up......then again they did not say whay they planted in those rafts.

Harold Sukhbir said:

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:

[Chris Smith]

I have been growing tomatoes in my raft troughs just fine since I found a disease resistant strain. I had many problems with tomato seeds that I bought. The plants usually became diseased after the second or third fruit set and died shortly after.

I now grow a large cherry variety that was a volunteer plant from a neighbors house. The volunteer tomatoes here do not seem to get diseased and I believe they have built up a resistance. I simply take cuttings and dangle them into the water. After a week there are roots the the plant is growing.

I have found that tomato plant roots will poison other plant roots if they come in contact. I now give tomatoes plenty of room and keep other plants at a distance.

[Sylvia Bernstein]

Hi Moe. These guys are all giving you great advice. I'd like to put in my vote that I think it is most likely primarly #3, which is causing stress that may be making the plant more susceptible to disease and unable to properly uptake nutrients. In soil you typically wouldn't plant tomatoes until late spring when the soil temps are no lower than 15c, and then you should expect very slow growth. Given that this is a trout system I might even make the bold, but unfortunate, assertion that you should avoid "summer" crops all together and focus on cool-weather, "spring/fall" crops like snow peas, snap peas, greens, broccoli, etc. Is the second system going to have warm water fish?

[MoeCanada]

Sylvia Bernstein said:

Hi Moe. These guys are all giving you great advice. I'd like to put in my vote that I think it is most likely primarly #3, which is causing stress that may be making the plant more susceptible to disease and unable to properly uptake nutrients. In soil you typically wouldn't plant tomatoes until late spring when the soil temps are no lower than 15c, and then you should expect very slow growth. Given that this is a trout system I might even make the bold, but unfortunate, assertion that you should avoid "summer" crops all together and focus on cool-weather, "spring/fall" crops like snow peas, snap peas, greens, broccoli, etc. Is the second system going to have warm water fish?

Thank you for the feedback everyone. I did take sylvia's advice and planted snow peas, lettuce, spinach,broccoli,basil.. and they all seem to be doing well. My second system is with goldfish right now but iam planning on getting some tilapia fingerlings, but am having difficulty finding a supplier in canada. If anybody knows of any supplier in US that will ship to canada please do let me know. Thanks again everyone for the feedback.

[Sylvia Bernstein]

Shipping to Canada is going to be a tough one, Moe, but I've sent an email to my supplier to see what they say.

am having difficulty finding a supplier in canada. If anybody knows of any supplier in US that will ship to canada please do let me know. Thanks again everyone for the feedback.

[MoeCanada]

Thank you everyone for your help. Just to update on what happened to my tomatoes. The first batch just started good but then the new growth became yellow and stunted and the whole plant slowly slowly bleached. The same happened with the second batch but the miracle happened with the third batch and it started growing pretty good with lush green leaves and is growing lot faster than my potted tomatoes. Now the things that i have tried and did work for me, so i wanted to update everybody incase somebody has the same issue with tomatoes in the start.

1. Do you think it is happening because my growbed is not mature ?

This definately effects the growth of tomatoes as i build two systems for experiment sake and the new system is still having trouble with tomatoes but the older one which is almost 3 months now has started getting good growth
2. Or my Growbed not deep enough

I didn't change the depth of my growbed so at this point that was not effecting the growth of tomatoes.
3. May be because of the water being cold as it is 15C ( i don't know if tomatoes like warm water)

This definately was another thing as i put trout in my new system and bought some tropical fish from petstore for experiment sake and raised the water temp to 24C and it did help a lot not only with tomatoes but pepper and eggplants as well which are now flowering
4. Or My flood and drain cycle being too quick

Flood and drain cycle is still the same so that had nothing to do with tomatoes not growing
5. Or is it Damping off disease

No.
6. Or is it some kind of nutrient deficiency

Ok this one is very important as i found that due to my high stocking density my system tends to drift down to ph 6.5 and i was adding hydrated lime to bring it up but in the last four weeks i didn't do that instead added crushed eggshells and let the system run at PH of 6.6 and i didn't have to add anything to the system. 

 

So in my experience with tomatoes three things are very important

1. Water temperature

2. PH ideal 6.5-6.9

3. System Maturity

 

In my newer system the PH is 7.6 which iam trying to bring down to 6.9 over a period of four days. Once it is at 6.9 i will plant a batch of tomatoes in the newer system to see how they will do and keep u guys posted on that progress.

 

Another thing as i wasn't able to get MaxiCrop here, i used another brand which is available in Local Hydroponics stores in Canada called " Mermix Seaweed" and is fish safe and healthy. I have used it with goldfish, bluegill and trout. Thank you all once again and i know iam new to aquaponics but still wanted to update what i have found useful till now.

[TCLynx]

Cool thanks for the update.

 

Yes I think water temp is probably a major reason many of those plants you listed are doing better since toms, eggplant, and peppers are all warm season or even tropical plants.

 

You may find that salad greens, and many cool weather crops will do better with the trout system.  Broccoli, cabbage, kale, kohlrabi, collards, peas, lettuce, beets, turnips, radish, carrots, and many more will do fine with cooler water once they get going.

 

Oh, and thank you for sharing the brand name of the sea weed available in Canada, I'm sure it will help others.

[Sylvia Bernstein]

Yep, again Moe, I think you know exactly what is going on.  Temperature is a big one.  Should be closer to 20 - 25c for plants you typically grow in mid-summer.  The other big factor here is the age of your beds.  Your bacteria colonies will build up over time and release more and more nutrients.  I wouldn't expect to see really good tomato growth until about 6 months.  Because your system is so cold that is slowing down the development of your bacteria colonies even more.  Because of the huge root systems tomato plants develop they will ultimately be happiest in a bed that is at least 12" deep.

Let me know if you would like us to ship MaxiCrop to you.

[Harold Sukhbir]

Hi All.

Yep,have to agree with Silvia on the question of maturity.I've had the same experience,after 3 attempts, tomato plants are finally growing approx. 4 months into maturity of the system.These last tomatoes are growing way faster and stronger than the previous set.I've also supplemented with boron and molybdenum as tomatoes requirements are on the low side in our fish feed.  I have a friend who runs water like a river(flooded) in long ground troughs, his Ph is about 7--7.5, his beds are a couple years old and he has amazing growth, and they say tomatoes don't like wet feet!,so i think maturity is definitely a factor. As i live in the tropics i am unable to comment on effects of water temps below 65 F. Thanks for sharing info on your progress.

[Mike Creuzer]

Just thinking out loud. Do you heat your system at all?

 

Live plant aquariums use under-gravel heating cables to stimulate convection currents through the gravel to prevent anaerobic conditions. The idea is that you gotta heat a tank anyhow, so why not in a way that it helps keep the plant roots healthy.

 

Maybe if you do any heating you do to your water in the grow beds around the tomatoes, you will create a warmer micro-climate around the tomato's roots.

Sylvia Bernstein said:

Yep, again Moe, I think you know exactly what is going on.  Temperature is a big one.  Should be closer to 20 - 25c for plants you typically grow in mid-summer.  [snip]

[Harold Sukhbir]

Hi Ted, thanks for that, I did it the hard way, wish you'd posted the plant PH chart sooner would have saved me a quite a few day's googling! Thanks.

[Sylvia Bernstein]

Good morning!  Ted, you are going to want to steer your aquaponics pH closer to a 6.5 - 7.0 range.  That is actually where you will see the best nutrient uptake (i.e. the most "green-ness" according to your chart).  Above 7.5 you are definitely challenging iron, and, even worse, you are challenging phosphorus which is a macro nutrient.