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Hi,

I've had tomato plants in the grow bed for almost 3 months now.  The plants are very tall and look good but they are not flowering or producing any fruit.  Any ideas from anyone would be greatly welcomed.

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I didn't see much information about your system on your profile.  Is your system indoors?  If so, I'd suspect lighting but I have no experience in that area.

It is in a greenhouse and a simple flood & drain system , 250 gallon tote tank 62 talapia 5-6 months old ,only  1 grow bed that is 2'x12'

George said:

I didn't see much information about your system on your profile.  Is your system indoors?  If so, I'd suspect lighting but I have no experience in that area.

What are your nitrites and nitrates at, Tomatoes don't like to bloom if there is too much nitrogen and it sounds like your generating a lot of waste for a smallish grow bed.

Yea everything is reading Hi except the Ph is at the lowest setting.

  So perhaps i give them some more light.; grow lights. Also i have been taken several (2-3) 5 gallon buckets of water out of the tank daily  & adding fresh  tap :well water that is higher in Ph.  But that does not seam to make any difference so i best figure out how to add more grow bed space  i.e. 4" PVC pipe as no room for another grow bed.

Jonathan Kadish said:

What are your nitrites and nitrates at, Tomatoes don't like to bloom if there is too much nitrogen and it sounds like your generating a lot of waste for a smallish grow bed.

What is the outside (air) temp? I've heard that tomatos can have blooms wilt from the heat before getting fertilized and thus never produce any fruit. Last year in Memphis we didn't really have any spring, and the tomatos did poorly all year.

Yup, that would seem like one of the drawbacks to an (particularly new-ish) AP systems...No fruiting plants like to (or can) flower then set fruit without adequate phosphorous and potassium. Both of which, (along with magnesium) seem notoriously lacking in new-ish AP systems...ones without the needed amendments.

Nitrates alone don't really cut it for much other than leafy greens. So either give up on the toms, cukes, zucchini etc...for the next 6 months or so...or look into a buffering regime with some of the things that will get your system some of the plant essential elements in the quantities needed to support the growth of heavy feeding plants such as tomatoes. Potassium bi-carbonate, dolomitic lime...

This seems totally typical for a new AP system and not anything that you a re doing "wrong".

Nitrogen in the form of ammonia is a much, much bigger problem for fruiting toms than nitrogen in the form of nitrates. Though like Johnathan says too much may not be good, but it is my belief that whatever your nitrate level...you would be OK if you had a proportionate amount of potassium and phosphate in there. The nitrate levels may be looked at as "too high", but only in proportion to the levels of potassium and phosphate. More a deficiency of the later, than too much of the former. Pretty typical if you ask me....http://aquaponicscommunity.com/group/fish-less-systems/forum/topics...

Though because of how late in the season it is (temps) it may be too late to do much about it now...

What do you mean everything is reading high? Are you using anything to buffer the pH? That doesn't seem like a lot of filtration for that number of fish. If your ammonia and nitrites are reading consistently >0 it is likely your biofilter cant keep up. If the fish are big enough to eat, removing some will allow your biofilter to catch up so you don't find them all dead someday soon.

Brian OLynek said:

Yea everything is reading Hi except the Ph is at the lowest setting.

  So perhaps i give them some more light.; grow lights. Also i have been taken several (2-3) 5 gallon buckets of water out of the tank daily  & adding fresh  tap :well water that is higher in Ph.  

My first thought is that it could be too hot, tomatoes often won't even bloom if it's too hot and there isn't enough of a temperature drop overnight.

New system, use some seaweed extract.

If pH is low, it could be way low, need to buffer.  If pH is reading 6 on an API test kit, it could be way low below that.  Need to buffer stronger than just a little tap water.  Some garden lime, some potassium bicarbonate or heck in a pinch even a little baking soda but be careful with that as it will add sodium that isn't very good for the plants.

If your pH crashing down below the readable range is not the cause of the ammonia then......

If ammonia and nitrite are high, you have too many fish or not enough filtration, a 4" pvc pipe for more plants won't help you there.  You have too many fish for the filtration you are providing, you would need to provide more filtration to feed the 4" pipe somehow.  Perhaps a bin full of scrubbies and some extra aeration while the water flows through it.

Wow, yeah it sounds like you have bigger fish to fry than a tomato plant that wont bloom...

Like TC says, get your pH back into a readable range with any carbonate buffer of your liking...before the whole bio-filter crashes...(potassium bicarbonate might be nice, but use whatever you have on hand immediately would be even better)...

And speaking of frying fish...it might not be a bad idea to have a fish fry with about 2/3rds of those tilapia...or add more bio-filtration...(2 more beds like the one you have should do)...were you planning on growing all those out full size in 250 gallons?

If you purposely waay overstocked your system because of plants like tomatoes, cucumbers etc...don't sweat getting rid of the extra fish as they're not going to help you get what you want anyways (unless your growing them for their ornamental vegetative qualities...which you are probably not)... once your systems "rules of thumb"-type proportions are in line and you're managing your pH properly and all, and your system has matured a bit...you shouldn't have any problems growing a tomato plant that pumps out tomatoes...



Vlad Jovanovic said:

Yup, that would seem like one of the drawbacks to an (particularly new-ish) AP systems...No fruiting plants like to (or can) flower then set fruit without adequate phosphorous and potassium. Both of which, (along with magnesium) seem notoriously lacking in new-ish AP systems...ones without the needed amendments.

 

Potassium is certainly a requirement for plants during fruiting/flowering/seeding stages.... and phosphorus for general growth....

 

But it's just not correct to say that new systems are "notoriously lacking"... in any of the above...

 

Magnesium, and/or phosphate deficiencies might be seen in a lot of heavily worked and depleted soils... but are extremely rare in aquaponic systems...

 

Many AP systems, particularly many in the US that draw source water from bores.... often suffer from nutrient lockout due to high pH....

 

And that high pH... is generally associated with "hard" water...general hardness...  by definition water high in mettalic elements... particularly magnesium... along with calcium and often iron...

 

I've never seen an AP system of my own, or any of my clients... that has ever exhibited signs of either a phosphate or magnesium deficiency....

 

Nitrates alone don't really cut it for much other than leafy greens. So either give up on the toms, cukes, zucchini etc...for the next 6 months or so...or look into a buffering regime with some of the things that will get your system some of the plant essential elements in the quantities needed to support the growth of heavy feeding plants such as tomatoes. Potassium bi-carbonate, dolomitic lime...

This seems totally typical for a new AP system and not anything that you a re doing "wrong".

 

Yes... the system in question definitely needs some pH buffering... and would benefit from a "Potassium" boost... and perhaps a Calcium boost as well.... both vital for tomatoes to set flower/fruit....

 

So applying an alternating Potassium and Calcium buffer (as above) is both beneficial.. to the pH level... and plants....killing two birds with the one stone...

 

Nitrogen in the form of ammonia is a much, much bigger problem for fruiting toms than nitrogen in the form of nitrates. Though like Johnathan says too much may not be good, but it is my belief that whatever your nitrate level...you would be OK if you had a proportionate amount of potassium and phosphate in there. The nitrate levels may be looked at as "too high", but only in proportionto the levels of potassium and phosphate. More a deficiency of the later, than too much of the former. Pretty typical if you ask me....

 

Not typical at all IMO.... and there's just such an ingrained "phosphorus" dependant mind set hang over from decades of soil fertilisation  thinking....

 

What many don't understand... is there is an inter-relationship between Phosphorus, Potassium and Calcium.... and too much Phosphorus.... can actually inhibit Potassium and/or Calcium uptake... and even a degree of other trace elements... including Magnesium....

One of the first crops I usually plant in a new system... and usually requested by clients.... are tomatoes....

And I've never had, or seen a problem.... and have posted pictures of both my own ... and other systems on this site... showing abundant tomato growth and yield.... in systems from day one...

Buffer your pH.... foliar feed with some Maxicrop periodically.... and you shouldn't have a problem with anything....

 

I think much of the "phosphorus" thinking actually comes from hydroponics as well where many people will switch from a higher nitrogen fertilizer mix for the veg stage of growing over to a lower nitrogen/higher phosphorus nutrient along with changing lighting for the fruiting stage.

However, in Aquaponics, if you are feeding fish and they are eating well, the fish food is usually a good source of both nitrogen and phosphorus so in aquaponics we usually only have to supplement some trace elements and potassium and if Iron lock out due to pH is an issue, chelated iron.  The seaweed extract takes care of trace elements and potassium and buffering the pH usually takes care of calcium and potassium.  Now exact amounts of what might be needed will vary greatly depending on the feed used for the fish and if solids get removed or not as well as the source water.  There are some people who never have to use calcium carbonate as a supplement or buffer because their well water is like liquid limestone.

Then again being where I live, most varieties of tomatoes just don't bloom through the heat of summer since our humidity means that the night time temps don't drop low enough to give the temperature differential they need.

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