What sign is it when the hornwort is entirely yellow, under sufficient light?

[Temp]

The small hornwort just spruced a branch, but the branch is completely yellowish.

Tips of the leaves are either yellow or brown.

What is this sign?

 

[krap101]

Is the hornwort in bunches?

 

[Temp]

Nope. Also, there doesn't seem to be any signs of algae buildup or anything. The water's clean, and there are a lot of dust and lint on the surface.

 

[Crepe]

What's your lighting/tank dimensions, fert regimen, and temperature. It's either too hot or too cold, or chlorosis due to a deficiency.

 

[Temp]

Lighting: 23W 6500K Philips Flouroscent Light.
Tank dimensions: Bowfront Tank. 1.2 or 1.3 gallons.
Fert regimen: None used, or available. I don't even know what it is.
Temperature: Between 20 degrees to 30 degrees Celsius. Don't have a thermometer nearby. I do know, the water temperature is the same with another tank, which has a lot of green hornworts. This small tank is used only for guppy fry, hence its volume.

 

[Crepe]

You have a nutrient deficiency. Chlorosis is the reduced production of chlorophyll, a green pigment. Lending to the yellow color you see now. You can fix this by reducing your lighting and/or using fertilizers.

Plant Deficiency Picture Diagram - Fertilizing - Aquatic Plant Central

 

[Temp]

Thank you for the picture, and your tip, I'll take both of those as references.

As for nutrient deficiency, if I were to add more grounded guppy food into the tank, does that count as fertilizing? I have not done that, nor do I have the test kits, so I couldn't tell anything.

 

[Crepe]

That's not the best idea. I would just buy a bottle of Seachem Flourish and do what it says on the bottle. Also cutting your lighting down to just 13watts or so will help tremendously.

 

[Temp]

Thank you again.

But, since I can't replace the light (since it's my desk lamp), I'll have to put the tank close to the window, where there's enough light for 13W.

 

[BillD]

It has been my experience with hornwort, that it is only a nice dark green under low light. Under bright light, the plant becomes browny red, and the whorls grow closer together. I have had it flower under really bright light.

 

[Temp]

Thanks for sharing, BillD.

 

[meegosh]

I'd say you either have a nitrogen or iron deficiency (or both). I'd recommend some ferts and see if that helps things. Is there any new growth? Is the new growth yellow as well? Are the tips dying off?

 

[Temp]

There's no new branches, but it did grew longer. The once white-yellowish branch is a bit green. But the larger, older branches have tips that are dying.

The new branch have no tips that are dying.

 

[meegosh]

If the older branches are yellow and the tips are being reabsorbed then I'd say it is most likely a phosphate issue. Yellow leaves can be attributed to many things but the tips being reabsorbed is usually a lack of phosphates.

 

[Temp]

The older branches aren't much of a yellow. In fact, the color structure of the branch itself is:

Green (Center) -> Green -> Green -> Green -> Brown -> Dead (Tip)

 

[meegosh]

I bookmarked this diagram. I think I found it on APC a while back. It serves as a good starting point in diagnosing nutrient deficiencies. See which looks more like what you are experiencing.

 

[Temp]

None of it. In my conditions, it just went from green to brown, and there's no signs of yellow in between those two colors.