A Community and Forum For Aquaponic Gardeners

Chelated iron and zink

I have found a liquid chelated iron and zink compound at Home Depot. I am hoping this will help improve the results in the system. Our tomatoes and peppers are small and sparse at best. There is some yellowing in the plants, but not real bad. Generally the growth is slow in all of our plants. Our seedlings start out good and then peter out. The pH is 6.4 to 6.6, NO2 is 0 ppm and the NO3 is at least 60 ppm. The ammonia hangs around .5 ppm. The catfish are happy and growing well. Our system is not quite 5 months old, but it seems it should be doing better than it is. Now, if I use this chelated product, I am not sure how much to put in the system. Thank you in advance for your help.

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Permalink Reply by John Cubit on October 31, 2012 at 9:37am

Vlad - Foliar spray, liquid based leaf spray of FE-EDDHA or a granule that would be applied to the bed or baskets. I assume that would be a gradual, time release breakdown. I was thinking the leaf spray since when the lights go out all the plants get a 10 second mist to wet the the plants.

Both are available at my local hydro shop and both are about the same price. The guy there recommend the granule for established plants, just wondering what your thoughts are?

Permalink Reply by Vlad Jovanovic on October 31, 2012 at 9:39am

Michael, I don't think Murray's method would work for me. I don't have a bell siphon (and I have 18,000 litres of system water)...I do however have 10 fingers, a gram scale to go with my particularly sized teaspoon, I know my system's water volume in litres (that's where the 10 fingers come into play) and can read a label... 10% iron 6% iron 28% iron...and a brain that sorta works (albeit half assed) most of the time...seriously we've all got different sized systems...Murrays regime won't really work "across the board" you won't go wrong with dosing 2-3 mg/ L...or you could of course just say "fuck it" and toss in a couple of "teaspoons" or whatever.

Michael Welber said:

Murray Hallam advises putting one teaspoon into the bell siphons once a month. I've been doing that and it's been no problem at all for the fish.

Permalink Reply by Michael Welber on October 31, 2012 at 9:40am

That's fine for you Vlad because you are heavily into the technology of all this but for those of us not so technically inclined we need more specific guidelines. I have watched my plants carefully and they aren't suffering from iron deficiency so the 1 tsp., once a month, for a 300 gallon tank seems to work. I purchased a chelate of the type that Sylvia recommends in her book. As I become more proficient I'm sure I will experiment with different approaches (already have) but those of us still in the beginner league rely upon some kind of "definite" amount.

Permalink Reply by Vlad Jovanovic on October 31, 2012 at 9:45am

John, I've not ever seen Fe chelate granules, just fine powders or liquids. You can always use the liquid directly in the grow bed as well as foliar. And vice versa...dissolve the granules in a given amount of water and spray as a foliar. Does the liquid have an "expiration" date...? (Not that I think it can go bad or anything, but companies do that sort of stuff...especially if they use some sort of agent to keep the Fe2+ from settling out/precipitating/coagulating etc...)...If it does, then go with the powder/granules...

Permalink Reply by John Cubit on October 31, 2012 at 9:52am

Makes sense Vlad. I will look at the actual granules and see if the have a mix instructions. I know the p-n-k I use for my potted indoor peppers has both a dry application and wet application. Thanks again.

Permalink Reply by Vlad Jovanovic on October 31, 2012 at 10:18am

That's what I'm saying Michael. A definite amount is 2-3 milligrams per litre. I've not read Sylvia's book, so I don't know what she recommends. I can only guess that it it the iron chelate product sold on this here site. (10% EDTA iron chelate made by GrowMore)...

Again, no disrespect meant towards you, (or anybody really...Murray included)...

Really though, if you are feeding your fish a half-way decent feed, and you have your pH under control (below 7) you should probably not be encountering any iron related deficiencies. And if its intervenal chlorosis (yellowing between the veins) of the older leaves and not the new leaves, it's a magnesium deficiency. Looks exactly the same as an iron deficiency, but on the older leaves instead of the new ones. (Mg is mobile in plants, Fe is not. Which means that the plant can 'pull' Mg out of older leaves and direct it toward new growth, they cant do that with iron, so the iron stays put where it is. So when there is not enough of it, the new growth will show that)...

Michael Welber said:

That's fine for you Vlad because you are heavily into the technology of all this but for those of us not so technically inclined we need more specific guidelines. I have watched my plants carefully and they aren't suffering from iron deficiency so the 1 tsp., once a month, for a 300 gallon tank seems to work. I purchased a chelate of the type that Sylvia recommends in her book. As I become more proficient I'm sure I will experiment with different approaches (already have) but those of us still in the beginner league rely upon some kind of "definite" amount.

Permalink Reply by Vlad Jovanovic on October 31, 2012 at 10:24am

It'll be nice if they have a "hydroponic application" instruction set. Don't use the fertigation or soil instruction set, since those numbers are often 10 to 100 times more than what you'd need in an AP or hydro set and setting...So using those numbers is a HUGE waste of money and product for a recirculating soil-less system...

John Cubit said:

Makes sense Vlad. I will look at the actual granules and see if the have a mix instructions. I know the p-n-k I use for my potted indoor peppers has both a dry application and wet application. Thanks again.

Permalink Reply by TCLynx on October 31, 2012 at 11:01am

On a side note, a recommended dosage amount per month is really assuming the iron is getting used up the same.

I have two systems running and I dosed them both with the same amount of the Gemplers Iron for plants. One system has maintained the 2.4 ppm of iron for weeks while the other system can use that amount up in about 3 days. It all depends on what the plants are doing with it and what kind of plants!

Now the need to add iron. It will greatly depend on the system but most of the top educators in aquaponics have found they need to dose regularly with Iron. This situation will vary though based on source water. I know three places running aquaponics commercial scale that definitely test and dose with Iron regulary, I believe they are all using either rain water or RO water and therefore their source water isn't coming with much iron in it. If you are running a backyard system and you can keep your pH low and you are using well water with a nice dose of iron in it and feeding a high quality feed, you probably don't need to dose with iron. I've found I do need to dose with iron in my systems but how much will depend on many things.

To help make it all a bit simpler, you can get a test kit to check iron levels

Iron test kit

Since that kit only tests to 1.0 ppm, you would need to use some distilled water and use say 1 part system water and 3 parts distilled water and then run the test and multiply the results by 4 to be able to read in the desired range.

My plants are doing far better since I started dosing the iron up more.

Permalink Reply by John Cubit on October 31, 2012 at 11:46am

This is from the Hydroponic shop, but I make no assumptions on what he is selling. I wish I could remember the brand it was something like hydro-iron or something..lol. My brain is frazzled right now but I will be stopping over tonight to take a peak.

Vlad Jovanovic said:

It'll be nice if they have a "hydroponic application" instruction set. Don't use the fertigation or soil instruction set, since those numbers are often 10 to 100 times more than what you'd need in an AP or hydro set and setting...So using those numbers is a HUGE waste of money and product for a recirculating soil-less system...

John Cubit said:

Makes sense Vlad. I will look at the actual granules and see if the have a mix instructions. I know the p-n-k I use for my potted indoor peppers has both a dry application and wet application. Thanks again.

Permalink Reply by John Cubit on October 31, 2012 at 11:59am

Thanks TC, I am growing a variety of Hot Peppers, mostly from Asia, Indonesia and the Philippians. They are all High Iron High Nitrogen plants typically found in humid areas. Even in the ground around the NE US I have to heavily dose with Iron and 20% Nitrogen fertilizer. Knowing that it does not translate to AP, I do know these will need the iron. I currently supplement the fish diet with dehydrated spinach and the leaves are starting to yellow. I only assume iron as the Nitrate level is 80ppm. The rest of the plants (NON pepper) celery, tomatoes are all fine. I was just concerned about if I should go with a foliar application or this granule from the hydro shop that the guy said can be added to beds or grow pots in raft systems.

TCLynx said:

On a side note, a recommended dosage amount per month is really assuming the iron is getting used up the same.

I have two systems running and I dosed them both with the same amount of the Gemplers Iron for plants. One system has maintained the 2.4 ppm of iron for weeks while the other system can use that amount up in about 3 days. It all depends on what the plants are doing with it and what kind of plants!

Now the need to add iron. It will greatly depend on the system but most of the top educators in aquaponics have found they need to dose regularly with Iron. This situation will vary though based on source water. I know three places running aquaponics commercial scale that definitely test and dose with Iron regulary, I believe they are all using either rain water or RO water and therefore their source water isn't coming with much iron in it. If you are running a backyard system and you can keep your pH low and you are using well water with a nice dose of iron in it and feeding a high quality feed, you probably don't need to dose with iron. I've found I do need to dose with iron in my systems but how much will depend on many things.

To help make it all a bit simpler, you can get a test kit to check iron levels

Iron test kit

Since that kit only tests to 1.0 ppm, you would need to use some distilled water and use say 1 part system water and 3 parts distilled water and then run the test and multiply the results by 4 to be able to read in the desired range.

My plants are doing far better since I started dosing the iron up more.

Permalink Reply by RupertofOZ on October 31, 2012 at 12:45pm

Yep... +1...

Oh... and with a fortnightly, or monthly cup of Maxicrop ... you shouldn't have any magnesium... or any other deficiencies either...

Vlad Jovanovic said:

Again, no disrespect meant towards you, (or anybody really...Murray included)...

Really though, if you are feeding your fish a half-way decent feed, and you have your pH under control (below 7) you should probably not be encountering any iron related deficiencies.

Permalink Reply by Leo White Bear on October 31, 2012 at 2:36pm

John-

Hopfully you found the iron/zink compound was found in the gardening department not the hardware dept. After that note to answer your question about the chelated iron amount. I add 1 teaspoon per 5-gallons water. So in my 100 gallon tank I add 105ml or approximatly 3.5 ozs. With the zink along with the iron I am not really too sure what amount to add.

I found my chelated iron liquid at a horticultural supply store. Maybe someone with the peoper experience with zink will be able to inform you better. Just remember that the iron will darken the water in your aquarium so don't get too excited, it will clear out.