Backyard Aquaponics
A place to discuss aquaponics

Hi there all, sorry for not posting for so long - have been too busy with the AP :-)

Have been planting lots of fairly mature seedlings out into the polytunnel from growing indoors and they seem to be doing OK, except that many of them are developing white leaves, some with deep green veins:


The tomatoes and cucumbers seem worst affected. not sure if it's a temperature thing, or a water problem / something missing? Haven't had a chance to do the full water test yet, but has anybody got any ideas?

(Temp has been 5C-30C)

Thanks guys.

As a thank you, here's a pic of the whole system at the moment -

looks like it could be aphid damage? Did you check the back of the leaves for the little bugs?

What's your pH?

Have you added any seasol or chelated Iron? When some one says green veins and pale leaves between, the next question is often, did it start on new leaves first? If so, it is probably a sign of Iron deficiency. Iron deficiency is often actually just the iron not being easily available to the plants because the pH is too high. Chelated iron stays more available to the plants even at the higher pH so is usually the best way to supplement.

I also ask about the seasol or maxicrop because the browning and crisping around the edges can be a sign of potassium deficiency.

I've had issues in my system with cucumbers struggling. My system has a high pH and my source water is not high in Iron. Cucumbers seem to be especially sensitive to iron imbalance at early stages of development.

Thanks for advice.

Our ph has always been fairly high, so sounds like supplements may be
required Any idea how much to use? We have about 5000l of water.

Many thanks

Andrew

How much to use will depend on the type of supplement you get. Probably start out reading the directions and base you first applications on the square footage of your grow beds and then use a bit less. I usually put a heaping spoon full under the water inlet pipes to each of my grow beds but that is the particular supplement I bought and they vary in strength.

That picture actually looks a bit like the cucumber suffered some deficiencies early on but may be doing better now. What are your other water tests like?

Older leaves yellowing is sometimes a nitrogen deficiency but that would be rare except in a new system with no fish.

You can also follow the directions for foliar feeding with supplements, just beware that extreme heat/sun after spraying a foliar feed can burn the plants so time the spraying appropriately. Also keep in mind that most Iron supplements will stain almost anything they are spilled or sprayed on. You want a chelated Iron that doesn't have additional metals in it as zinc and copper are generally not good for fish.

Hi Andrew, Sure its not Volcanic ash

OK, did the full water test this morning - fairly different from the last test I did!

pH - 7.5
Ammonia - 1.5 ppm
Nitrite > 2 ppm (possibly 4-5)
Nitrate 100ppm !!
O2 - 12-15

and we do have a chlorine / chloramine reading of 1, which is a surprise. Seems the make-up of our tap water has changed now it's warming up here.

A week ago I had to do a significant water top-up (about 1/3) which would account for the Cl, but these are the highest Nirate / Nitrite readings I've ever seen. That would suggest the system is cycling, but why do I still have an ammonia level? I haven't added any ammonia for about a week (during the water change).

Thanks for all the advice gys!

also - there are no signs of aphids yet, it's the older (lower?) leaves which get hit first (they started off green and healthy)

I'll go in search of supplements - no seasol here unfortunately!

You should be able to get Maxicrop Andrew... it's made in the UK... same stuff (I actually prefer it)..... and you can get "maxicrop with iron"...

http://www.maxicrop.co.uk/

Thanks Rupert,

Have tracked it down - http://www.capitalgardens.co.uk/v3/natural-seaweed-extract-plus-sequestered-iron-p-8879.html looking good!

How do the rest of the numbers look? Anything particular I should be doing / not doing? (No more ammonia for a while I'm guessing, and buy a rainwater tank so that I don't use tap water anymore!)

Thanks guys - feeling a lot more sane now, less worried.

Definitely no more ammonia... just let the system do it's thing.... plant some more plants, the seedlings should boom with all those nitrates...

Shop around Andrew... in the US... they sell a "gallon" bottle... about 3+ litre...

And they sell a 6 pack case for about $20US....

http://www.horticulturesource.com/maxic ... ase--p116/

http://www.shopmania.com/shopping~onlin ... 89397.html

Thanks - I've got a small one ordered to get me started, then I'll get some larger quantities in when they're in stock.

Looking at those figures, would I be safe to start putting fish in? Looks like it's cycling fairly well, although I never seem to be able to get down to 0 ammonia.

I wouldn't put fish in just yet Andrew, not with that nitrite reading, not even if you salted....

How long has the ammonia and nitrites been reading at those levels... and what's your day temp?

I have to admit I haven't tested for a couple of weeks, but it was much lower then, and I added a fair bit of ammonia a week ago.

Daytime temp in polytunnel is 20-35deg max , min down to about 5-7 overnight. I promise I'll do more regular tests this week - I'm looking for the nitrite spike to disappear aren't I?

We are getting some algae in the water now too - time to build the cover for the tank!

Yep, cover the tank and patients. Test every day or two to see when the ammonia and nitrite drop to 0. Then you have the choice of either doing one more dose of ammonia to 1 ppm and see how long it takes till the ammonia and nitrite drop to 0 again or once the ammonia and nitrite reach 0 you could add fish and just watch levels carefully while you finish the cycling with fish.