Backyard Aquaponics
A place to discuss aquaponics

Interesting observation between the DWC and the GB's lately, I have for some time noticed what looks to be an iron deficiency with the lettuce and other plants in the DWC but I havnt added any iron chelate for a while after watching Nates video on good and bad iron so Ive been winging it to see how it all goes. The lettuce, coriander, chard, cabbage and basil still grow well in the raft, its just that I can see some deficiency of some kind in the lettuce and coriander. Yellowing in the leaves.

Anyways, today I was checking the leaves on the coriander in the raft and I can see that it is lacking something but then I looked over to the media beds and the coriander is looking much greener and healthier so it cant be the system. Once again Im seeing better growth in the media beds with certain plants. Over time I am leaning more closely to believing I am removing too much nutrient or something with the filtration before the DWC but Im not real sure.

Here is a picture comparison of the coriander.

Hey charlie new place looks good.... well the little bit you showed us lol. I love Byron Bay, they actually have a ban on places like Mc Donald's and KFC And i love the care free attitude they have there, its refreshing and a reminder to slow down and live a little. They seem so happy with the simple things out there.

Hey just a thought on your DWC and possible nutrients deficiency, could you boost it with seasol to see if that brings it back as the filters wouldn't be able to filter that out, if no difference then maybe something else??

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Hi Kitacooch, thanks for feedback. Byron is cool layed back place, we are inland a bit from there in a little town so even more layed back in ways. It really is very beatiful through that area and Im looking forward to the next part of our lives.

I do add seasol to the system about once or twice a month. I think the thing to take on board is this is the same system with the same fish and same water. The GB's are CF and the DWC obviously has a flooded nature so in my opinion they are relatively the same in a few ways but the DWC is heavily filtered.

Maybe someone with experience can help and Im open for suggestions please.

Must be a minor nutrient that is being produced in the gravel beds and is somehow locked in there or more concentrated in there

I agree, Mantis. What it is Im loosing through the filter needs to be determined because I have no idea what it may be. Its obviously not iron. I realise the commercial operations reuse the solids but I dont understand this process.

I really want to get a better understanding of mineralisation and pre-filtering. Much to my own dismay I may start a new thread. I understand pre-filtering and I am not against removing solids but I do have a lot of questions that surround such filtering, mineralisation and reintroduction.

What are we removing. What are we mineralising. What are we re-introducing.

Its not all about a visual waste product.... or is it?

I know that in media, solids are right there being mineralized and the roots have direct access to that or the worm castings that are right there too.

I expect that there are some things that are just not quite as easily water soluble or take more work/effort to get them dissolved into water.

I know, not a terribly scientific answer.

Anyway, one way I know of that the RAFT aquaponic system operators recover some of the nutrients from their discarded solids is they will remove the solids from their systems into a "sludge pond" which they heavily aerate until those solids become stabilized (basically bubble the heck out of it till you can go grab a hand full of that solid sludge and sniff it and find it doesn't stink anymore, yea not very scientific either.) Once the sludge is stabilized, you can let it settle to the bottom and pump/siphon out the clear, very mineral rich water back into your aquaponics system (or I know of some operations that sell this mineral rich water for pretty outrageous prices.) The solid sludge can then be removed and de-watered and used for soil gardens or fed to worm bins or whatever, it is also very nutrient rich fertilizer.

I primarily grow lettuce in my raft beds and haven't had much luck really identifying particular deficiencies in that lettuce as compared to the lettuce growing in the towers which are media based. I test and dose for Iron so I'm not dealing with that. Potassium seems to be my biggest nutrient deficiency at the moment and I can recognize that on my basil in the towers. I think I may also be seeing potassium deficiency in some of the lettuce but haven't really learned to visually recognize the symptoms in lettuce yet and some of the plants are showing other problems which I haven't figured out yet.

Learning to recognize nutrient deficiencies (other than Iron) in different plants is not always as easy as it sounds. Susanne Friend actually Recommended the "Book Hunger Signs In Crops" that has helped me quite a lot even though it doesn't depict most of the plants I actually grow.

Ah... a "burginator"...

A burginator? where does that term come from?

Came about during a discussion several years ago... about system design, "clarifying tanks", "nutrient banks"... and in relation to commercial applications of DWC/NFT...

So yep... take off the sludge from your radial flow filter.. or settling tank (sorry... clarifier).... and aerate it vigorously...

If you really want to maximise the process... hit it with some black strap molasses... (and/or even heat it if required)...

Turn the aeration off for an hour... so that the sludge settles out...

Then skim the nutrient rich water from the top and feed to a sump that feeds your DWC/NFT....

If you want to be really sexy, adjust your pH or other supplements at the same time... like with a hydroponic dosing system...

Periodically drain off the sludge, de-water... and throw the sludge on your compost heap.... worm bins...soil garden...

And watch both the compost heap... and your plants go bat shit...

Start the cycle again...

All is revealed....

Thanks TC and Rupe. Interesting comments and food for thought.


Anyways, a little update now that spring is upon us. The warmer weather is really starting to add that last dimension to the system and the plants are starting to power along. Im glad that I have been experimenting with a few different plants this year and see what I can and cant grow. What I am impressed with is the rhubarb and artichoke... wow they are going crazy right now and the leaves are massive. Also happy with my manual pollination for the miniature nectarine tree, I now have a substantial number of bulbs starting and hopefully get a good crop. Beans are going nuts now too.

The raft is looking good. I have been mineralising the filter solids externally and then reintroducing the liquid after settling and I am seeing an improvement in the raft deficiencies so hopefully Im doing something right. Got a number of lettuce, basil, coriander, chard and I even put a couple of carrots in to see what would happen and dam me if they are sprouting nicely, be interesting to see what they do and how they grow. Bit of fun anyways.

Got a couple more wicking buckets in for tommies and will set up some runners this weekend and start training them. Looking forward to an assortment of heirloom varieties.


Anyways, enough dribble.... pics!

Great work as usual

Looking good! Funny how the chard's roots are so colorful.

Looks great Charlie, plants are coming along nicely . What's the plant in the second and third to last pic (just before the tomatoes in the buckets)?

Some nice growth there Charlie

I'm guessing you don't reuse the pots in the DWC?