Backyard Aquaponics
A place to discuss aquaponics

Sorry dlf, I missed your post.

I get it in bulk and there aren't dosage rates on the bags, I'm guessing they assume because it's intended for commercial growers that they'll be testing and figuring out their own rates.

I'd probably still add the amount required for the entire system (ie: the ½ or full level teaspoon per 1000L rates), but add it into the 9L watering can then water that into the GB as you suggested, probably just after the GB has started a fill cycle. I'm not too sure if it would make any difference.

I used to add a ¼ teaspoon into the 500L at the first sign of Iron deficiency, but as I mentioned, for some time now I've just been adding a "pinch" about every 4-6 weeks and I haven't had any deficiency issues since.

Thanks DLF, for directing us back to this thread, I've been meaning to come back to this thread for a while now and add some relevant info.

Earlier in the thread Matthew mentioned the EDDHA turning water red and I stated, and showed with pics, that this wasn't the case if used at the rate of 1x 1/4 level tspn per 500L (or 1x 1/2 level tspn per 1000L).

Well it turns out the teaspoon I'd always used for dosing the system, as seen in the pics, was waaay out. I recently bought a set of proper measuring spoons and what I thought was a 1/4 lvl tspn actually turned out to be a 1/8 of a lvl tspn... So you can half the EDDHA rates I've quoted with the pics.

In saying that, you can also half the rate required to successfully treat Iron chlorisis. I've fixed it a couple of times in the past with what I thought was the equivalent of 1/2 a lvl tspn per 1000L, but it turns out it was only a 1/4 of a lvl tspn per 1000L.

Once you fix Iron chlorosis with that rate (only takes 3 days) I would recommend simply adding a "pinch" per 500L of water every 4-6 weeks depending on what type of plants you have, ie: every 6 weeks for small leafy greens, lettuce, herbs, Asian greens etc, and every 4 weeks if you have fruiting plants or large greens such as spinach or silverbeet in the system. That's provided the fruiting plants make up no more than 1/3 of the surface area of your grow beds, at a higher rate of fruiting plants you will most likely need more, especially if you have tomatoes in the sytem.

The information that you posted regarding the pH range of DTPA chelated iron doesn't appear to be correct. I couldn't find the chart or text from the Haifa group so I went to Akzonobel. -https://www.akzonobel.com/micronutrients/products/product_stability/. Instead of 6.5 it is stable up to pH 7.5 (not that it will matter for someone with a pH of 8.4 or lower). Spray applying most types of iron avoids the pH lockout issue.

I'm not sure where you got your dosage, hmm metric teaspoons (didn't know these even existed, learn something new everyday) - any chance you can point me to the source for this dosage? How many grams of Fe-EDDHA in a metric teaspoon if you weigh it (I'll just use a generic 6.25 mg for now, I'm sure it's different though)? This seems much lower than the standard rate of 2 mg/L (or 7.58 mg/gal) every 3 weeks which is in Nate Storey's video on calculating iron amounts (https://www.youtube.com/watch?v=qczagOJG5mI). His is a starting point and he says himself that he uses less since he knows the system well. Working through his calculations and using a 6% EDDHA results in 33.3 mg/l roughly (at the 2mg/L iron dose needed and figuring for 6% iron in the solution).

So basically I'm seeing that your dose is about 1/5 of the standard dose (from the video and based on my flawed estimate of gms per metric teaspoon) or less since the measuring spoons were off and it looks like you were using 1/2 tsp instead of 1 tsp (that would make the dose 1/10th to 1/20th the standard). I'm not sure it will turn the water red at the higher dose but it has turned the water red for some people, whether they measured the dose, whether it was before we really knew the dose or whether they just dumped it in , it can have that effect although it might not have had they measured and it certainly wouldn't have at your dosing rate. Like you, I doubt that there is much difference between products so what I'd like to see and what will convince me that there is no problem with the addition of Fe-EDDHA is repeating the test using the full standard amount of Fe-EDDHA - since systems vary it's probably safe to figure that someone somewhere will use this amount. Since I spray apply iron I don't have the EDDHA to test this myself or I would.

You've done it now Scotty... This topic has become a bone of contention with me lately.

http://www.haifa-group.com/users/ronald ... 92551.aspx

Me!... Personal experiences with my own systems over the years, helping with customers systems, customer feedback, and many forum discussions.

Over the years it became standard procedure on the forums when recommending doses of particular products to use ‘X’ teaspoons per 1000L as the guide... For example, before Nate Storey’s videos popped up the standard rate widely recommended on forums for using Iron chelate to fix Iron Chlorosis was 1x level teaspoon per 1000L... and it worked.

Don’t know, don’t need to know, don’t care!

Again... Don’t know!... and this time I really don’t care!

I’ve only watched three of Nate storey’s videos... Parts 1 & 2 on Iron, and another where he tells viewers not to use carbonates when controlling pH (good luck with that, try it and let me know how that works out)... Those three were enough to make me realise that much of what he says should be taken with a grain of salt. I’m sure a good deal of it may be relevant in his situation, with a commercial scale system, but it doesn’t always apply or even work for the average backyard gardener, especially those that just want a simple, easy, low fuss AP system... and not a chemistry set.

For example, his recommendation that you quoted, based on UVI procedures, of adding 2mg of Iron per litre of water every three weeks???... What is this based on?... What type of fish are in the system, how many of them, what size, what feed rate, what type of feed, what Iron level does the feed contain?... What type of plants are in the system, vegetative or fruiting, what are their Iron requirements and absorption rate, what season is it, are the plants using all of that 2mg between doses or is it building up?

I can tell you that I’ve had customers do the sums and try and achieve this 2mg rate, even just as a once off, it takes a lot of Iron chelate, if you used EDDHA you wouldn’t see your fish ever again. Water colour aside, I’ve had a customer treat their water at 1x level tspn per 1000L (proper set of measuring spoons) and then test the iron level in the water, it was less than 0.5ppm... So it would take possibly 6 or even 8 level tspns per 1000L to achieve the 2mg rate... This is grossly excessive and not required IMO... and I believe it would definitely build up in the system.

As I’ve previously stated, I have fixed Iron chlorosis using the equivalent of just a ¼ level tspn per 1000L. Then maintained the system for many months using just a “pinch” of FeEDDHA every 4-6 weeks. My current display system has now been running for over three years. I ran it for quite some time, possibly 18 months, without ever adding iron, without issue. It wasn’t until I had a large chilli bush that started fruiting very heavily that the system become iron deficient and I treated it at the ¼ tspn per 1000L rate. I then successfully maintained it for quite some time with just a “pinch” every 4-6 weeks (single IBC system with 500L of water)... a far cry from 6-8 tspns per 1000L every 3 weeks. In over three years I’ve only had to dose that system at the ¼ tspn rate twice, both times when I’ve had plants fruiting heavily.

Prior to Nate’s videos the majority of my customers were comfortable with the idea that for home based systems that were well designed, sensibly stocked, using a good quality feed, and planting according to the amount/size of fish and the season... a reactionary aproach was the best method in regards to nutrient deficiencies... and the majority of them had great success, with few deficiency issues. When they did have deficiency issues they were usually easily identified, and rectified quickly and easily in most cases.

Since Nate’s videos have become popular I have far more customers with nutrient deficiency “dramas”, including “perceived” nutrient deficiencies that turn out to be non-issues. I have customers testing, or wanting to test, just about every single aspect of their system, down to individual nutrient elements. They almost always end up chasing their own tails around in ever decreasing circles because they focus on this or that individual element and add certain products to try and counter their latest perceived nutrient issue, with little or absolutely no regard to, or knowledge of the effect it will have on other nutrients already in the system.

IMO, the average backyard AP’er is better off focussing on getting their ratio of fish per sqm of GB right for the plants they have in the system at the time, or vice versa, using a good quality feed, and keeping the water pH within suitable range... then simply keep a keen eye on the health of the plants and take a reactionary approach to nutrient deficiencies. It’s much easier, much cheaper, less stressful, less complicated, and they are far less likely to create issues.

As we’ve already covered, what is the “full standard amount”... If you’re referring to Nate’s rec’ rate, then I can tell you, as I mentioned back up in the post, with EDDHA you will never see your fish again... but whatever type of Iron chelate is used, that level is definitely not required IMO, certainly not as a regular maintenance level, or even as curative dose to rectify Chlorosis... a poofteenth of that 2mg amount will fix chlorosis.

OK, this basically gives me what I was looking for. I generally treat only when I see a deficiency but occasionally add a bit extra. My experience has been similar to yours regarding the amount of iron used in my system - the additions are few and far between (but my pH is low so I really shouldn't need much if any). I suspect that's true of many people here. On the other hand from what you've said and what I've seen here on BYAP, the system water turns red with the addition of EDDHA iron chelate at the standard rate mentioned in Nate's video.

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For anyone trying to figure out what they need

Bottom line is you can spray apply just about any of the iron chelates or ferrous sulfate and they will work. The best iron for spray application is probably Ferrous Sulfate (which is not a chelate) because it contains about 20% iron and is relatively cheap. Spray application uses less iron but might require multiple applications compared with adding to the system water. For most people the pH of their system water comes down over time and they could get by using regular iron (ferrous sulfate) by spray application until that happens. For those in the US with Maxicrop plus Iron, this uses regular iron at 10% so you get both the iron and the seaweed spray application done at the same time. Application rates for foliar spray are usually listed on the bottle for soil grown plants and it's no different for AP.

If you have high pH system water and you want to add iron in an available form, then the best iron for addition to the system water is the Fe-EDDHA (usually 6 or 7% iron). It is more expensive than the others but little is needed to correct most iron deficiencies. At low doses, at or below 1 tsp/1000 L it's not going to turn the system water red enough to cause any problems and probably is sufficient to remedy the iron deficiency. At about 5 tsp/1000 L (and likely starting lower) the color change will likely be a problem.

Getting back to the OP "Where to buy and what to buy for fertilizer and additives?" I find this a little like asking, what vitamins and mineral supplements should I be eating?

Answer... Probably none if you have a good and varied diet, yet many people still pop them anyway.. Use a good fish feed and the whole subject about what you have to add, at what doses etc is possibly a moot point. I've run systems for years without adding anything but fish feed.