Need Help Understanding Iron

[Koi]

Hi guys I've noticed a lot of people on this forum that either have some kind of chemistry/science background or are just incredibly intelligent. I've come to ask anybody that could fill in the gaps of my research or show me what I'm misunderstanding.

To keep it short I am injecting co2 into my 65 gallon tank and I am using dry salts for fertilization. I have been creating solutions for a couple weeks now but have since reverted back to dry dosing since I suspect I am making a mistake in creating my solutions. Among other nutrient deficiencies It seems that I am lacking in iron.

This is the part hopefully someone could better explain what I'm doing wrong or missing . I've been dosing 1/4 tsp Plantex csm + B 3 times a week. I've read that EDTA precipitates iron at ph of 6.5 and my tap water degassed is somewhere from 8.2-8.4. I have since stopped creating the solution and made two changes. I dose plantex dry 30 minutes before lights come on and my ph reads somewhere from 6.6-6.4 (the api test kits are kinda hard to read and probably not that accurate) and I supplement with .2ppm  11% DTPA fe. 

Ive included some pictures with closeup to show what I'm seeing

Here are some of my tank parameters:

Nitrate: 30-40 ppm most of which comes from my tap water and livestock I do add about 5-10 ppm with KNO3

Potassium:  25-30 ppm from KNO3,K2SO4 and KH2PO4

Phosphate:  4-5 ppm KH2PO4

GH: 7 dGH

KB: 6dKH

The ph of my tank is around 7.6 before co2 comes out

When the light comes on ph stays around 6.6-6.4 the whole day

As I said earlier I'm not sure how accurate these readings are since I usually watch my fish response but this is the lowest I can go before stress

 

 

I'm noticing chlorosis and I see pinholes in older leaves of rotala hra. Because of how much K I'm dosing Im starting to think its because of poor substrate since I ran out of root tabs a month ago. I use eco complete

The rotala macrandra is starting to look better, before I started adding DTPA it looked similar to the hra

[Will Billy]

Im not sure this would make a difference or not. Im wondering using co2 injection if the chelated iron is becoming ferric fe+3, i wonder if using flourish excel that would make it ferrous fe+2 if that wouldn't help improve your iron deficiency. As both o2 and co2 are oxidizers, your co2 injection is creating a reaction to the iron of your fertilizer. I might be wrong, but its just a thought. 

[Koi]

Thank you for the research topic @Will Billy. I should have prefaced that I am a dummy with science and I have a very general understanding of what is going on haha. But you did remind me of a video I need to review that talks about ferric and ferrous iron but I was under the impression that plants could use both but preferred fe2+

Could you explain your idea with the excel? I'm not sure what excel would do.

 

 

[Ken]

Once again CoOp to the rescue:

https://www.aquariumcoop.com/blogs/aquarium/iron-fertilizer?_pos=3&_sid=44899cea2&_ss=r

Edited February 3, 2021 by Ken

[Will Billy]

Fe+2 is just more easily metabolized than FE+3. Here is a link to the description. 
https://www.seachem.com/flourish-excel.php

[Koi]

15 hours ago, Ken said:

Once again CoOp to the rescue:

https://www.aquariumcoop.com/blogs/aquarium/iron-fertilizer?_pos=3&_sid=44899cea2&_ss=r

Not really what I'm asking, but thanks

[Seattle_Aquarist]

Hi @Koi

Of the following, which are based upon your dosing levels and which are from actual test results?
 

Quote

Here are some of my tank parameters:

Nitrate: 30-40 ppm most of which comes from my tap water and livestock I do add about 5-10 ppm with KNO3

Potassium:  25-30 ppm from KNO3,K2SO4 and KH2PO4

Phosphate:  4-5 ppm KH2PO4

 

[Koi]

Hi @Seattle_Aquarist I recognize your name from other forums, but I'm assuming thats you atleast haha.

All three are based on my dosing levels, I used a nutrient calculator but I wrote the wrong one KNO3, I meant to say 10-15 ppm KNO3

The 30-40ppm is off of a test kits so not sure how true it is.

I'll mention that this is the dosing Ive been doing for about 3-4 weeks before I was putting in around 25 ppm KNO3

 

 

[Seattle_Aquarist]

1 hour ago, Koi said:

Hi @Seattle_Aquarist I recognize your name from other forums, but I'm assuming thats you atleast haha.

All three are based on my dosing levels, I used a nutrient calculator but I wrote the wrong one KNO3, I meant to say 10-15 ppm KNO3

The 30-40ppm is off of a test kits so not sure how true it is.

I'll mention that this is the dosing Ive been doing for about 3-4 weeks before I was putting in around 25 ppm KNO3

Hi @Koi

Yes, that is me.....I'm on several forums.  I see a lot of folks seem to think the problem is iron (Fe) related but I don't think so.  Iron is one of the immobile nutrients so when their is insufficient available iron (due to low dosing, or incorrect iron, or nutrient interaction) the symptom (interveinal chlorosis) will show up in the newest leaves of the plant / stem.  Yes your new leaves have a definite 'yellow' look to them however with interveinal chlorosis the veins should be green with yellowish areas between the veins and I just don't see that.  The leaves almost look uniformly yellowish.  If you had low nitrate levels I might suspect that is the issue but with a nitrate level greater than 20 ppm nitrate issues are unlikely.


What could the problem be then?  Other plants in your other photo give a clue.


Notice the arrows in the second photo pointing to leaves.  Do you see the marginal chlorosis (yellowing leaf margins) and the interveinal chlorosis) dark green leaf veins with lighter interveinal areas?  When that occurs on recently matured or order leaves it is typically caused by insufficient magnesium (Mg).  Why?  Because magnesium is one of the mobile nutrients which allows the plant / stem to steal magnesium from older leaves and move it to new growth (if there is sufficient available).  Magnesium is one of the secondary nutrients that is necessary for photosynthesis which gives plants their healthy green color.  As the older leaves lose their magnesium the leaves show exactly the symptoms seen in the picture.
 

Quote

C. Interveinal chlorosis. Interveinal chlorosis first appears on oldest leaves.

1. Older leaves chlorotic, usually necrotic in late stages. Chlorosis along leaf margins extending between veins produces a "Christmas tree" pattern. Veins normal green. Leaf margins may curl downward or upward with puckering effect. Necrosis may suddenly occur between veins. Potassium or calcium excess can inhibit uptake of magnesium...magnesium deficiency

When the external magnesium supply is deficient, interveinal chlorosis of the older leaves is the first symptom because as the magnesium of the chlorophyll is remobilized, the mesophyll cells next to the vascular bundles retain chlorophyll for longer periods than do the parenchyma cells between them. Leaves lose green color at tips and between veins followed by chlorosis or development of brilliant colors, starting with lower leaves and proceeding upwards. The chlorosis/brilliant colors (unmasking of other leaf pigments due to the lack of chlorophyll) may start at the leaf margins or tips and progress inward interveinally producing a "Christmas" tree pattern. Leaves are abnormally thin, stems are brittle and may have a tendency to curve upward. Stems are weak, subject to fungus infection, usually leaves drop prematurely.

The above description of magnesium deficiency pretty well describes what we see in the older leaves in the second picture.  A plant species may not show all of the symptoms listed above and some plant species are better able to tolerate low magnesium levels than other species.

But why are there issues with the new leaves, why are they yellowish?  There are two possibilities that come to mind.  The first is that is normal coloration for that species when exposed to high light; remember the light becomes brighter as the plant grows closer to the light source.  The other possibility is the stems cannot move magnesium from older leaves to new growth quickly enough and the lack of magnesium is keeping photosynthesis from giving the leaves a healthy green color.

What to do?  If it were me I would continue dosing everything as you are currently with the possible exception of backing down the nitrate dosing so it doesn't exceed 20 ppm.  I would also add some magnesium to your dosing schedule.  Where to get magnesium?  Go to your local drug store and pick up some Epsom Salt (aka magnesium sulfate / MgSO4).  Get the cheapest stuff on the shelf with not additives or scents.....maybe $1 - $2 for a pound. 

Here are your dosing instructions: 
1) After your weekly water change (you are doing weekly water changes aren't you) add 3/8 teaspoon of Epsom Salt per 10 gallons of water volume in the tank, this will provide you with 5 ppm of Mg. 

2)  Thereafter, when you do your weekly water change add 3/8 teaspoon of Epsom Salt for each 10 gallons of new water added to the tank.

Now the hard part, waiting for 3 - 4 weeks.  Do not watch any of the existing leaves, they will not change and may continue to decline.  After you have started dosing the additional Mg watch the new leaves as they emerge, do they look healthier?  greener?  Does the growth rate increase (due to improved photosynthesis)?  If so then you are on the right path.  As the leaves mature you should not see the interveinal chlorosis.  Keep us posted and let us know how things progress!  Hope this helps! -Roy

*** An interesting note is that most water supplies have more than sufficient calcium for healthy plant growth they do not have sufficient magnesium.

Edited February 4, 2021 by Seattle_Aquarist
sp

[Koi]

@Seattle_Aquarist Thank you so much for clarifying that for me. Boy am I glad I included the full photo with the close up haha.

I actually started adding 5ppm magnesium this week. I bought an 8lb bag 2 weeks ago because I was seeing similar symptoms in my bucephelandra and anubias but I wasn't confident in my diagnosis. Your description definitely helped me and clear some of my confusion. I actually noticed the new leaves on my crypts have come out alot nicer since adding epsom salt, its

54 minutes ago, Seattle_Aquarist said:

The other possibility is the stems cannot move magnesium from older leaves to new growth quickly enough and the lack of magnesium is keeping photosynthesis from giving the leaves a healthy green color.

 a more even brown and almost red to it.

I must say the arrows was a nice touch, it made it a lot more clear for me. I might not have been sure what you were talking about without it haha. I'm definitely gonna steal using the arrow for pictures

 

 

54 minutes ago, Seattle_Aquarist said:

The other possibility is the stems cannot move magnesium from older leaves to new growth quickly enough and the lack of magnesium is keeping photosynthesis from giving the leaves a healthy green color.

Could this be part of the reason why the older leaves on my rotala are unhealthy? Or is there something else causing the necrosis?

1 hour ago, Seattle_Aquarist said:

*** An interesting note is that most water supplies have more than sufficient calcium for healthy plant growth they do not have sufficient magnesium.

Really good to know. I cut off using equilibrium some time now which might explain alot now.

Again I appreciate you taking time out of your day to help me, you cleared up a lot of questions for me. Definitely will update this thread  when I see some progress.

[Seattle_Aquarist]

25 minutes ago, Koi said:

@Seattle_Aquarist Thank you so much for clarifying that for me. Boy am I glad I included the full photo with the close up haha.

I actually started adding 5ppm magnesium this week. I bought an 8lb bag 2 weeks ago because I was seeing similar symptoms in my bucephelandra and anubias but I wasn't confident in my diagnosis. Your description definitely helped me and clear some of my confusion. I actually noticed the new leaves on my crypts have come out alot nicer since adding epsom salt, its

 a more even brown and almost red to it.

I must say the arrows was a nice touch, it made it a lot more clear for me. I might not have been sure what you were talking about without it haha. I'm definitely gonna steal using the arrow for pictures

 

 

Could this be part of the reason why the older leaves on my rotala are unhealthy? Or is there something else causing the necrosis?

Really good to know. I cut off using equilibrium some time now which might explain alot now.

Again I appreciate you taking time out of your day to help me, you cleared up a lot of questions for me. Definitely will update this thread  when I see some progress.

Hi @Koi,

I'm glad to help!  Yes, if the older leaves are suffering it is possible that the lack of magnesium is the cause.  Rotala tend to do better with substrate nutrients rather than water column dosing; in fact most of the genera in the Lythraceae family tend to respond better to substrate nutrients.  -Roy