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Dwarf water lettuce - phosphate deficiency?


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I have dwarf water lettuce that isn’t quite thriving. Some of the leaves turn yellow and slowly disintegrate. According to the aquarium co-op nutrient deficiency graphic, it looks like the issue could be nitrogen deficiency or phosphate deficiency. Nitrates in the tank are generally quite high even without fertilizer (20-40ppm). So that would suggest that the issue is a phosphate deficiency? From the Co-op blog, it says phosphate deficiency is uncommon especially if I don’t have any phosphate absorption and I feed flake food to my fish. In addition, all the my cryptocorynes are doing well, bacopa caroliniana is green but new leaves are tiny, water sprite is turning brown and fading. Does phosphate deficiency make sense in this case?

I did have a lot of brown diatom algae growth that some new otos cleaned up last month. Could the BDA have depleted the phosphates to such a degree?

 

 
 

 

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Hi @Phinny,

So how do you cover the other two macro-nutrients (P&K), three secondary nutrients (Fe, Ca, Mg), and multiple micro-nutrients?  Plants require more than just nitrates to be healthy.  The yellowing (chlorosis) I see in your photo is not likely related to insufficient available phosphorus (P) 0 chlorosis is not a symptom of a phosphorus deficiency. 

It is more likely caused by iron (Fe) or magnesium (Mg).  If it were my tank I would start adding Seachem Equilibrium per the instructions on the bottle.  It will add needed potassium, iron, magnesium, calcium, and manganese.  When you do your weekly water change (you do water changes don't you?) add sufficient Equilibrium for the amount of new water added.  It may take 4 weeks or so before you start seeing an improvement.  Watch the new leaves as they emerge and mature......DO NOT WATCH THE EXISTING LEAVES - they wll likely not improve.  Hope this helps! -Roy

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Hi @Phinny

With a hardness of 18 dGH I suspect it is mostly calcium in your area of the country.  We can increase the magnesium level with minimal impact on your hardness by adding Epsom Salt (magnesium sulfate; MgSO4).  Go to your local drug store and buy the cheapest Epsom Salt on the shelf with no scents or additives.  Add 3/8 teaspoon per 10 gallons to your tank.  This will bring your magnesium level up to the recommended level of 5 ppm and only increase the hardness by 1.15 dGH.  When you do water changes add 3/8 teaspoon per 10 gallons of new water added.

As for iron pick up some Seachem Flourish Iron.  It is made from ferrous gluconate and is easier for plants to absorb when the pH is above 7.0.  Dose per the instructions on the label.

Let's start with those two changes and see how the plants respond over the next four weeks.  Keep us posted, pictures are always appreciated!  -Roy

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@StreetwiseI agree but I remember that one of my friends had been keeping water lettuce in a lidded tank with high intensity lights above and the steady drip of the condensation from the glass lid caused the leaves to be burnt by the lights and rot. Not that this is the case here but just something to watch out for when  keeping water lettuce in a lidded tank with super intense lighting.

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Good point @Jungle Fan! I could even see droplets on the leaves acting as lenses. I've had some emergent plants get a little toasted when they grew too close to the light in a couple of tanks.

I actually removed my lid from my 16 bow just a week or two ago because I had added water lettuce and it wasn't growing-in as well as in my open tanks. 

Edited by Streetwise
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@Streetwise it's a trade off, I usually went with open tanks when I used floaters over the convenience not to have to do top offs in a lidded tank, they just do so much better without the lids. That said I enjoy not having to do top offs with my current tank, although a tank with some Amazon frogbit, the driftwood roots sticking out the tank and some peace lilies as added above the surface foliage would have been tempting if it had not been for the center brace of the frame.

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Has anyone had success with floaters with a lid? I prefer to not have quite so much evaporation, but my lids aren't tight. I misaligned them to allow more air flow, but there is still some condensation. BUT, I'm also not having tremendous success with floating plants at the moment, and I think, if I'm remembering correctly, that they did do better before I got the lid on the 40b. They did OK under the lid of the 20 hex, but that was mostly plastic... hmmm..... Water level is a couple of inches low, and I've been remembering to fertilize more, but no spectacular improvement,

@Seattle_Aquarist, do you just have this mineral knowledge in your head or is there a place to look it up? I'm in Ohio with hard water, but I don't really know the components. 

It would be simpler if I just didn't like floating plants!

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1 minute ago, Kelly S said:

Has anyone had success with floaters with a lid?

I’ve kept red root floaters with a lid and they did well for me. Mind you it wasn’t completely sealed off. There was a 1 inch gap between the front of the tank to the lid. Maybe that slight opening helped. To be honest, I didn’t know lids and floaters don’t always mix.

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Hi.  I open my lid every day for 3-4 hours and I also vent the lid when closed.   Have to watch for jumpers so if that’s an issue just lower your water level and they should do fine.   Just don’t keep water level at rim with lights on all day.  The Epsom Salt idea sounds like a good idea as well.   👍🏻

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On 3/12/2021 at 6:18 PM, Kelly S said:

Has anyone had success with floaters with a lid? I prefer to not have quite so much evaporation, but my lids aren't tight. I misaligned them to allow more air flow, but there is still some condensation. BUT, I'm also not having tremendous success with floating plants at the moment, and I think, if I'm remembering correctly, that they did do better before I got the lid on the 40b. They did OK under the lid of the 20 hex, but that was mostly plastic... hmmm..... Water level is a couple of inches low, and I've been remembering to fertilize more, but no spectacular improvement,

@Seattle_Aquarist, do you just have this mineral knowledge in your head or is there a place to look it up? I'm in Ohio with hard water, but I don't really know the components. 

It would be simpler if I just didn't like floating plants!

Hi @Kelly S,   Most of this knowledge I acquired from various sources over six decades of having aquariums (12 years of planted aquariums) and 4 decades of gardening.  Nutrient deficiencies and interactions are the same whether plants are terrestrial or aquatic.  -Roy

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  • 3 weeks later...

Hi @Seattle_Aquarist - As you suggested I dosed my tank with iron and epsom salt over the past month. I noticed some more robust root growth after the first week but chlorosis has not improved much. Should I continue with the iron and epsom salt? Is it time to try dosing with a more complete fertilizer such as Easy Green? Thank you!

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Hi @Phinny

I'm glad to hear you are getting improved root growth but I agree you are not getting the results that would indicate the problem is resolved.  If it were my tank I would start doing 50% water changes every week to try to keep the nitrates down as much as possible, dose Easy Green once a week as directed to get some potassium, phosphorus, zinc into the water.  Typically 'small leaves' can be the result of insufficient zinc or phosphorus.  If it is phosphorus the leave veins may take on a purplish color under the leaves.  I would continue to dose the magnesium and Seachem Iron as you have been.  Try this for 4 weeks and let us know how things progress. Hopefully the nitrates don't climb much over 40 ppm.  -Roy

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