Huh... Here's a new one to me. - The Planted Tank Forum
 
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post #1 of 7 (permalink) Old 12-29-2013, 03:53 AM Thread Starter
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Huh... Here's a new one to me.

I've been having some minor issues with necrosis on older leaves for some time now. The worst affected was the Red Sword (E. Barthii?). The leaves were constantly warped and crumpled up. The rest of the plants were growing pretty well.

Just so you have some background, I learned how to walk in a hydroponic greenhouse and have managed commercial research greenhouses for many years. So you might say I have a solid understanding of plant nutrition.

I've been tinkering with my fertilizer components to try to correct the issue for most of the past year. Since this is a low tech tank modifying things slowly is really the only course of action. My first thought was iron, no response. I have very soft water so I upped my Ca, no response. I tinkered with the NPK ratio's and got a nice algae outbreak. I've been adding in CSM +B so I thought that was okay on those.

This last month I ordered a new batch of dry ferts and saw MnSO4. I thought what the heck I'll try increasing this one a smidgen. So I ordered it in and combined it into my normal regimen.

Holy smokes the tank has taken off. The red sword has just shot straight and vibrantly colored leaves to the top of the 125g. The crypts decided it would be a good time to send out runners and spread. And the val's are back to trying to overrun the tank. Even the anubis decided it could grow faster now.

The only deficient looking thing in the tank really was the red sword. Apparently this was a limiting element in an otherwise well balanced system.
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post #2 of 7 (permalink) Old 12-29-2013, 04:26 AM
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i dont know much about ferts, the one think i know is the sword is a root feeder. so if you are not adding something to the substrate under it that might be the prob. i am not really sure what would cause this as i have only jused ferts a couple times in my tanks. im really low tech with normal hood lights but what i do have tends to do pretty well. for the heck of it you might try a jobes plant food spike in the roots of the sword. they are plant, fish and shrimp safe.
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post #3 of 7 (permalink) Old 12-29-2013, 04:27 PM
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That's surprising. I wouldn't have thought Mn would become limiting with the use of Plant ex. Did you increase dosing frequency? As far as I know Mn is similar to iron in regards to being unstable in water. So any increase in frequency could have resulted in the increased plant health. I don't think it would have anything to do with the S contained in it since it provides very little.

Out of curiosity what/how are you dosing, water change regime and tap water parameters?

It's not very often I hear of a Mn deficiency like this. I just wonder if there is another explanation you've overlooked. It certainly isn't impossible just unlikely. I would expect to see other deficiency issues before Mn.
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post #4 of 7 (permalink) Old 12-29-2013, 08:04 PM Thread Starter
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Quote:
It certainly isn't impossible just unlikely. I would expect to see other deficiency issues before Mn.
Now that was exactly my thought as well. Mn is not the first one you think of when looking for deficiencies. Heck it's near the bottom of the list with Zinc.

My regimen hasn't changed in the three years I've had this tank up. Once weekly dosing of NPK, Ca, Mg, & Trace (very soft water). I usually run it a bit on the lean side with the macro's. 50% water change every couple of weeks. Bi-annual staggered filter cleanings.

Substrate is builders sand capped with gravel. So there pretty much no CEC other than from the organic material.

Everything else has remained constant with the exception of the addition of the MnSO4.
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post #5 of 7 (permalink) Old 12-30-2013, 03:46 PM
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Wow that is odd. It does sound like it was a Mn problem. I wonder if the batch of Plantex was poorly mixed of otherwise lacking in Mn.
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post #6 of 7 (permalink) Old 12-30-2013, 08:44 PM
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I'm curious, what's your pH? If high it breaks the EDTA chelator used in CSM+B, including Mn EDTA, which makes it harder to absorb. And in hydroponics, it also reduces general Mn availability:



Though when high pH is an issue, in my experience I always see Fe issues first. And hydroponics is not an exact parallel, as with that only the roots are exposed to the nutrients; for us, the leaves are exposed too and may have different absorption properties.

How much MnSO4 did you add?

Funny you should mention Zn. I recently increased Zn & Cu, and saw a boost in Limnophilia Aromatica growth. Was temporary though, it returned to normal after about two weeks. Hopefully your improvement will not also be temporary.
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post #7 of 7 (permalink) Old 12-30-2013, 08:56 PM
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Good point Darkcobra. I've often wondered why PH seems less important for aquatic plants than those grown in hydroponics. I know in hydroponics the optimal PH is 5.5-6.5 range for nutrient availability. How less important is it? why? I'd love to understand more about that subject.
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