Aquaponic Gardening

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I need some advice from AP veterans. My plants have mostly stopped growing and are losing leaves.

System is two months old and has been fully cycled for the last month. System includes:

• 330 Gal fish tank with 30 small goldfish (will be replaced with yellow perch in the fall)

• 12' x 2' x 1' grow bed with hydroton (plus several hundred red worms) and one bell siphon

• Small sump tank.

• A small NFT system for 18 plants in netpots

• All enclosed in a greenhouse.

• System cycles about every 24 minutes

Plants include basil, pepper, okra and squash.

Water tests have remained steady:

• pH - 6.6

• ammonia - .25

• nitrite - 0

• nitrate - 40 ppm

• temperature - 82 to 85 degrees

Plants did fine before fish were added, probably because I added powdered seaweed. Week before last I added a bit of iron to the mix, and last week when the plants stopped growing, I added some potassium.

I realize the system is not mature enough to expect a lot of fruiting at this point, but plants should at least not be losing leaves.

Weather has been unseasonable hot and humid. 

My questions:

- Should I just add more seaweed power or liquid?

- Is the ratio of fish to grow bed volume seem OK?

- Is cycle time adequate? (Bed fills up in 20 minutes and then takes four minutes to drain).

- Should I add more potassium? I have no idea how much to add.

- Is water temp too hot?

- What else should I consider?

Thanks for sharing your expertise.

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Your system is very young and life is complicated ;) Have patience and don't expect mother nature to be controlled so easily. It will take some time for your system to mature and the nutrient profile to become what the plants need. You have to learn to read your plants to see what they need.

Jonathan - Thanks for the reply — and for the nifty leaf illustration.

I noticed that some of the leaves in your pics are wet...and the whitish lesions on your peppers look like sun scald/burn and not an essential element deficiency. Wter will act as a magnifying glass for the sun's rays. (Though leaf in the background, it looks the the beginnings of a magnesium deficiency)...

Wet leaves are also prime relestate for like a million different fungal pathogens...

The amount of potassium in MaxiCrop is probably fine for basil, lettuce, etc...but might not be for much else...Buffering with potassium bi-carbonate would probably offer more K than that. Or using a combination of both might be even better.

MAxiCrop/Kelpak/Seasol aren't excactly used because they have a high N-P-K value, quite the opposite really (nor should you be adding a high N-P-K value fertilizer...organic or otherwise). They offer a good amount of micro-nutrients and contain a lot of bio-regulating hormones (mostly Auxins and Cytokinins), but thats about it. But you weren't specific about what seaweed powder, or what seaweed liquid you were adding (that would be helpful), as there are some very divergent products out there.

You'll probably need to satisfy yourself with leafy greens for a while (6 months to a year) or, come up with a good 3 pronged alternating buffer regime (dolomitic lime, a calcium based lime, and potassium bi-carbonate) and/or fish/bacteria safe additions (like Epsom salt)...

They're seems to be a rash of new aquapons (that part is great), who have this idea that they can get cycled with ammonia, and right away plop in things like tomatoes, cucumbers, peppers, eggplants etc...(There's a reason heavy feeding plants are called 'heavy feeders'). I have no idea where those kinds of ideas are coming from (I'm sure they're probably coming from somewhere), but that's not a very realistic approach. Especially for getting things past the seedling or veg stage (in a way that you could even remotely describe as 'plants doing good/great').  

It can be done, but it's gonna take either a bit of an integrated strategy on the part of the operator (i.e cycling with humonia, buffering with carbonate buffering agent that contains potassium and/or magnesium, additions like Epsom salt and so forth) or it's gonna take some time (about a year say) for a system to build up a store of those essential elements through fish effluent. The third option might be... it's gonna take a string of per chance 'lucky coincidences' in the operators environmental set and setting (not likely, but possible).

Dennis, I'm not picking on you (at all) in particular, as they're seem to be lots, and lots, and lots of folks all doing the same types of things, and having the very same types of problems and I'm just curious as to why this would be happening? I'm definitely not picking on you or anyone else. I guess I'm wondering if all the people promoting AP (websites, e-books, videos, whatever) are presenting information in a little bit of a skewd or un-realistic manner, or if folks are choosing to gloss over and not take heed to pesky details like "...it takes time for an AP system to mature, or it will take a bit of a more involved approach to grow heavy feeders/non-leafy greens right off the bat..." when they read/hear them from those that are 'selling the dream'...? Maybe a combination of both? IDK

+1 Vlad..

another thing to consider is what are you feeding the fish?  a high quality fish feed (appropriate for your fish) is one of the most important elements to establishing a healthy and productive ap system

You might also try adding more oxygen. Fish will use up most the oxygen in a system. for a better desription see my video on youtube on this subject. Plants don't need oxygen as much as fish, but they do still require some. http://youtu.be/3NZiNo0_TtM

It also looks like you need to supplement with some iron.

Vlad -

Thanks for your thoughtful reply. Some good things here to consider. I think you're on to something about false expectations being created from all the hype from people selling AP systems, etc. Forums like this provide a good counter balance to the hype.


Vlad Jovanovic said:

I noticed that some of the leaves in your pics are wet...and the whitish lesions on your peppers look like sun scald/burn and not an essential element deficiency. Wter will act as a magnifying glass for the sun's rays. (Though leaf in the background, it looks the the beginnings of a magnesium deficiency)...

Wet leaves are also prime relestate for like a million different fungal pathogens...

The amount of potassium in MaxiCrop is probably fine for basil, lettuce, etc...but might not be for much else...Buffering with potassium bi-carbonate would probably offer more K than that. Or using a combination of both might be even better.

MAxiCrop/Kelpak/Seasol aren't excactly used because they have a high N-P-K value, quite the opposite really (nor should you be adding a high N-P-K value fertilizer...organic or otherwise). They offer a good amount of micro-nutrients and contain a lot of bio-regulating hormones (mostly Auxins and Cytokinins), but thats about it. But you weren't specific about what seaweed powder, or what seaweed liquid you were adding (that would be helpful), as there are some very divergent products out there.

You'll probably need to satisfy yourself with leafy greens for a while (6 months to a year) or, come up with a good 3 pronged alternating buffer regime (dolomitic lime, a calcium based lime, and potassium bi-carbonate) and/or fish/bacteria safe additions (like Epsom salt)...

They're seems to be a rash of new aquapons (that part is great), who have this idea that they can get cycled with ammonia, and right away plop in things like tomatoes, cucumbers, peppers, eggplants etc...(There's a reason heavy feeding plants are called 'heavy feeders'). I have no idea where those kinds of ideas are coming from (I'm sure they're probably coming from somewhere), but that's not a very realistic approach. Especially for getting things past the seedling or veg stage (in a way that you could even remotely describe as 'plants doing good/great').  

It can be done, but it's gonna take either a bit of an integrated strategy on the part of the operator (i.e cycling with humonia, buffering with carbonate buffering agent that contains potassium and/or magnesium, additions like Epsom salt and so forth) or it's gonna take some time (about a year say) for a system to build up a store of those essential elements through fish effluent. The third option might be... it's gonna take a string of per chance 'lucky coincidences' in the operators environmental set and setting (not likely, but possible).

Dennis, I'm not picking on you (at all) in particular, as they're seem to be lots, and lots, and lots of folks all doing the same types of things, and having the very same types of problems and I'm just curious as to why this would be happening? I'm definitely not picking on you or anyone else. I guess I'm wondering if all the people promoting AP (websites, e-books, videos, whatever) are presenting information in a little bit of a skewd or un-realistic manner, or if folks are choosing to gloss over and not take heed to pesky details like "...it takes time for an AP system to mature, or it will take a bit of a more involved approach to grow heavy feeders/non-leafy greens right off the bat..." when they read/hear them from those that are 'selling the dream'...? Maybe a combination of both? IDK

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