Yellow Sprouts!! Low Nitrates? High pH?

[Capt. Killingfield]

What is the water temp running past the plants? Is it possibble for you to plant them higher in their pots?

Psinet, the water temperature reads 23C/74F.

I had to sink a couple of the plants lower into their pots because the growplugs werent wicking enough water up through the L.E.C.A., and they were drying out. I have a feeling my heirloom tomato is slightly stunted because of it.
Is it possible for the growplugs to absorb too much moisture?

RupertofOZ, is there a notable difference between hydroponic "ebb & flow", and "flood & drain aquaponics"? I was under the assumption they were the same principles and techniques, just different nutrient sources.

I will get a test kit, and go from there . Thanks for your time guys.

[bigdaddy]

Hi Captain,

I gave you a bum steer , sorry about that, the API fresh water master test kits work well for me don't know if you can get them in the states, don't know if age of aquariums send overseas. I didn't read where you are from when I posted. I'm sure there are plenty of shops over there that will help.

My tomatoes have done well in a constant drain grow bed and a flood and drain grow bed and none have or had blossom end rot, or any other wet problems, so far. I think that's because I have plenty of air going into my fish tanks. as for temperatures I grow winter veges for winter and summer veges for summer and all do well.

Cheers.

[Wendy in BC]

BD we have them in canada, so for sure they're in the US as well

[Psinet]

Actually... they grow a wide range of vegetables in Antartica... including tomatoes... using hydroponics...

Yes Rupert, I am sure they grow lots of things in Antarctica using technology - like heating the tomatos.

But tomatos dont grow in arctic/antarctic climates unassisted due to temperature. Simple.

Wheat doesn't grow on waterfalls unassisted due to the inumerable moulds that attack it when too wet. Simple.

Both of these factors can be understood and applied to AP to grow better plants with smarter decisions.

I dont care how good your system is, running 4c water over a tomato seedling from halfway up the stem will turn the tomatos yellow/black spotted - and it has NOTHING to do with nutrients.

In answer to your question Capt K - yes it IS possible for plugs to get too wet. No matter how well oxygenated the water, you cannot ensure all water sitting against the roots is oxygenated because there isnt always sufficient and even water flow. Plugs sunk deep get wet and become anaerobic - no water passes through them, they simply stay wet because the surface tension of water is too great amongst millions of tiny holes with no real pressure applied. Raising them so that only the very bottom of the plug contacts the water flow allows the plug to aerate between cycles, and allows the roots to find their own way.

[RupertofOZ]

Both of these factors can be understood and applied to AP to grow better plants with smarter decisions.

I dont care how good your system is, running 4c water over a tomato seedling from halfway up the stem will turn the tomatos yellow/black spotted - and it has NOTHING to do with nutrients.

You're quite right... it has nothing to do with nutrients... it has to do with commonsense... growing plants within season... or adapting the environment to extend the "season".... and nobody argued otherwise...

And nobody would plant a tomato seedling and flood water "halfway up the stem"... if you did, regardless of soil, hydroponics or aquaponics... or even temperature... it would suffer/rot/die....

Nor would you attempt tomatos, or most plants in a system with 4 degree water...

In answer to your question Capt K - yes it IS possible for plugs to get too wet. No matter how well oxygenated the water, you cannot ensure all water sitting against the roots is oxygenated because there isnt always sufficient and even water flow. Plugs sunk deep get wet and become anaerobic - no water passes through them, they simply stay wet because the surface tension of water is too great amongst millions of tiny holes with no real pressure applied. Raising them so that only the very bottom of the plug contacts the water flow allows the plug to aerate between cycles, and allows the roots to find their own way.

Perhaps this is hydroponic practice... bad practice if it is...

Even in NFT when "plugs" are most commonly used... the water is oxygenated... and the water level only a film.... the plugs are never "submerged"...

Some people might use "plugs"... or even net pots... within media.... in hydroponic ebb & flow...

In aquaponics we don't do any of that... for those very reasons...

We either sow seed directly, or if planting seedlings... shake the bulk of the seedling mix off, and/or rinse... then transplant...

Even if "plugs" were used.... we don't flood to within any more than 1"/25mm of the media surface... and frequently flood & drain, with either a rapid drain siphon... or an overflow standpipe/timer... allowing oxygen pull down past the lateral (near surface) roots... and some period of "dry" time...

(Another difference between aquaponics flood & drain.. and hydroponics ebb & flow... where the flood level in ebb & flow systems is usually to the top of the media, or even above... and overflow systems usually incorporated)

If you really feel the need to use plugs... then yes you could sit them on the surface while the roots develope... providing your climate isn't too hot, and/or the roots don't dry out... and there's enough cappillary action to supply moisture and nutrients...

But you'd be better off just teasing the plug apart and planting normally... or shaking away most of the plug material...

In aquaponics we don't usually use media like perlite/vermiculite, coco coir or any other water retaining media... because it is too likely to retain too much moisture... and lead to root rot problems...

Aquaponic systems are also highly oxygenated in comparison to any soil system that might be "flooded" and rely on quick drainage to prevent root rot... and similarly to most hydroponic systems, which are usually not oxygenated at all, other than water return to the reservoir, and minimal water turnover....

Most ebb & flow systems are likewise not oxygenated other than by water return into very small reservoirs.. with infrequent water turnover...

[trout]

In aquaponics we don't usually use media like perlite/vermiculite, coco coir or any other water retaining media... because it is too likely to retain too much moisture... and lead to root rot problems...

Actually Rupe
I think there might be a huge place for perlite/vermiculite in aquaponics.

Last November I planted two thumb size pieces of ginger in 3 parts perlite
and 1 part vermiculite in a perforated basket in the growbed..
It grew fantastically so much so that the baskets is literally bursting the sides.

Not bad considering I live in a temperate zone and ginger is tropical.

Just some data.
The temperature in the basket rose gradually during the day and decreased
during the night.
Whereas the temp in the flood and drain bed would exhibit a 15% temp
difference every time it flooded and drained. 3X per hour in my case.

I would think that plants would prefer a constant temp around the roots
as opposed to the continual saw tooth temp profile in the bed.

Im thinking that my capsicums might do better in the baskets.

For winter crops I will be testing the method on leeks, broccoli, garlic
and see what happens.

BTW when are you supposed to harvest ginger?


cheers Lou

[RupertofOZ]

Not saying that you can't use those media Trout... certainly within a container... but not generally as the complete media in a flood & drain system....

Wicking beds and seedling starter trays (with infrequent watering)... are other examples...

[Psinet]

Rockwool provides a no-mess solution to planting, and I suspect this is what the "plugs" are. These are fine for AP systems as long as they are not planted too deep. However, you cannot tease apart rockwool plugs without damaging roots.

I use the mini Jiffy Peat Pellets. This way I have the option of simply planting the tiny peatbag whole, or ripping it and rinsing off all roots - but I usually just plant the bag. I always ensure only the bottom 2-5mm of the plug contacts the water surface, which is around 25mm below the media surface.

In the hydroponics systems I have used in the past, rockwool cubes (150mm square) are placed on a large flood table. The enormous exposed surface area of the water is enough oxygenation in this case, as the water is only allowed to around 25mm deep but is over a surface of many square meters. This is never drained, but is a flow-through system. The base of the plants in this case are 120mm+ above the water line, avoiding stem rot etc. I once implimented an oxygenation solution to the nutrient, but the roots covered the table and blocked everything within days, and there was no real difference in plant growth - as the 150mm rockwool cubes had enough oxygen,water and nutrient to meet plant demand.

[Yabbies4me]

Actually Rupe
I think there might be a huge place for perlite/vermiculite in aquaponics.

Perlite... maybe!

Use vermiculite in AP, or even hydro... and I reckon you're mental!

Just my opinion... after a decade and a half in hydroponics.

Cheers, Yabbies.
.

[RupertofOZ]

I'm the opposite.... Perlite... never.. a complete PITA...

I've got no problem with a 25:75... perlite/vermiculite mix as a seedling starter mix... outside of an AP system... or even in hydro...

But I wouldn't use either in ebb & flow.... or even net pots in NFT.... and most certainly not in aquaponics...