I came back from vacation and now my Ludwigia Arucata is yellowing

[beanbag]

Hello folks,

This plant has lived in a jar with nothing added for at least 6+ months before I set up my current shrimp tank, and it was fine.

Then it grew for about 3 months since I set up this tank, and it was fine.  I didn't dose much fertilizer, except maybe 1/5 to 1/10th the recommended dose of ThriveS, an all-in-one fertilizer.  Thus nitrates always read at zero.  I assume there is a tiny bit of nitrate from the decaying shrimp poop.

So anyway, I leave for a 1 week vacation, and after I came back, I noticed that this plant is yellowing while the other plants are fine (moss, s. repens, MC, DHG).  I think the very tips / new growth is still green, but the older leaves are yellowing and falling off.  Most guides suggest a nitrogen deficiency, but there are many people who run planted shrimp tanks with no fertilizer at all and their plants are still fine.  Plus my other plants seems fine, so maybe this is due to something else?

The only things I can think of out of the ordinary is missing one week's worth of water change and very low fertilizer dosing.

Edited January 13, 2020 by beanbag

[sdlTBfanUK]

Does this help, is the lighting on a timer etc when you were away to match the normal lighting? It may be the lack of the usual fertilizer as well.

https://www.practicalfishkeeping.co.uk/features/how-to-grow-ludwigia-arcuata/

From what I read this plant is one of those that new growth is at the top and the leaves at the base die off, so you would need to prune it to stop it getting long leafless stems?

I haven't any experience with this plant though!

Simon 

[beanbag]

yes, the light is on a timer.  So that means the plants got less light while I was away since the other lights in the house were off.

Edited January 13, 2020 by beanbag

[sdlTBfanUK]

It may possibly be the combo of less fertiizer and light but I'm sure you will be ok, with it only being a week! Just percevere as normal and I expect it will soon recover!

If the yellowing leaves are nearest the base though it may be natural wastage and you may need to cut the very tops to stop it growing too quickly upwards and grow bushier? 

Simon

[beanbag]

Just to update that I went back to my normal, very low dose of fertilizer, but the Ludwigia are still dying, from the bottom up.  The tips are green and growing, but the bottom parts are rotting away.  So far, I can only think of two possible reasons:

1) I have been feeding my shrimp less, so maybe they aren't making enough ammonia and nitrates for the plants

2) About 2 months ago, I changed the lighting so that it was a complete blackout at night and only 7 hours of medium light a day.  This did a great job of getting rid of algae that was growing on the plants, but maybe now I need more light again?