# Ludwigia Cuba Melting



## MrsH (Feb 22, 2009)

My ludwigia cuba is melting right at the surface of the substrate (black flourite). All my water readings are good, high-tech, pressurized Co2, daily ferts, root tabs, etc, etc.

Most all other plants are growing very nicely. Any ideas with the cuba?? Thanks!


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## ashappard (Jun 3, 2006)

what about flow?

and with nutrient hungry stems like L.cuba you cannot underestimate their ability to suck the nutrients out of the water column right after you dose. when I kept a large stand of it, I had to increase dosing 250% so other spp. didnt suffer its appetite for macros

any pics?


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## chagovatoloco (Nov 17, 2007)

Can you post the specs on the tank? How old is the substrate?


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## JAXON777 (Jan 4, 2007)

Just a guess but I bet its light. Mine look great at top but where it gets shaded it melts to just a stem. Maybe spread them apart so that the light gets all the way to the substrate or use some midground plants to hide the stems.


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## ashappard (Jun 3, 2006)

a guess, yes and it may be right - but consider this :

when macros are low and bottom out / fluctuate between zero and a little -- sometimes the older growth will suffer. especially when the deficiency sets in over time. Also lack of flow in the plant beds will cause nasty rotting and other problems. you'll have happy new growth until things get very bad, but a set-in macro deficiency or stagnation of flow can look that way - with older growth dying, melting.

I say this because in extremely dense stands of greedy plants like L.cuba and L.aromatica I have near darkness at the bases and no melting. but I do have high macro levels in the water column and good flow at the bases. good flow doesnt have to be 'bend the stems to the substrate' flow. just as long as the water is moving and does not stagnate.

actually one of the downsides to CO2 misting (for some) is an upside when troubleshooting flow. If you see microbubbles entering and leaving the plant beds, then flow is fine.


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## MrsH (Feb 22, 2009)

Specifics:

The cubas are new to the tank and spaced pretty well. Plenty of circulation. 

Substrate (flourite black) / tank is about 9 weeks old. 

Daily ferts, pressurized Co2 diffused through an external bioreactor / uv sterilizer loop on the output of one of the three 2217s.

pH: 6.4
kH: 2.5
Co2: 30ppm
Nitrate: 0
Nitrite: 0
Ammonia: 0

I think the tank itself may just not have enough light to grow the cubas. Although all the other plants are doing very well, the L cuba seems to be a light / fert hog. Running only 160W, 6,000k, 9 hrs per day (3 on, 6 off, and 6 on) over a 150.

Thanks for the feedback!

BTW - no pics of the melting stems - just replanted.


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## MrsH (Feb 22, 2009)

JAXON777 said:


> Just a guess but I bet its light. Mine look great at top but where it gets shaded it melts to just a stem. Maybe spread them apart so that the light gets all the way to the substrate or use some midground plants to hide the stems.


How much light do you have over them?


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## ashappard (Jun 3, 2006)

160W over a 150? yeah, thats a bit low. jaxon's probably on to something.
you should still be able to grow it without melting though. 
what other plants are doing very well?
any tank pics at all?


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## MrsH (Feb 22, 2009)

ashappard said:


> what other plants are doing very well?
> any tank pics at all?


Pics under my profile. However, the ones loaded aren't very good. I have much better pics but they are too "large" to load to this forum.


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## ashappard (Jun 3, 2006)

hard to tell exactly what plants are there, and how healthy they are 
but from the distant angle they do look pretty healthy. 
most plants will do better in softer water, examine your dosing, CO2, flow, etc yada yada.

L. cuba can show its potential in as little as 2wpg - heres a couple shots :
this was under crappy old PC lights (2x96W) in a 19" deep tank
even more light (like metal halides) and higher micros will bring out deeper red. 
higher macros will give you larger stem diameter and good leaf health.
at the base of these stems, near darkness because of the dense growth. 
but no rotting, or leaves falling off.



















in my experience, ludwigias do best in the abundance of nutrients.


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## Tex Gal (Nov 1, 2007)

Thanks Ashappard for sharing your knowledge. I'm sure it's helping a lot of people.


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## ashappard (Jun 3, 2006)

MrsH said:


> Specifics:
> 
> .....
> 
> ...


nitrate zero? not good.
you'll need NO3 and PO4 in detectable quantities and in proper ratio 
if you want success with something like L.cuba

I dont use test kits so I cant throw stones, but have you calibrated 
your test kit(s) against a known solution? do you know that nitrates are *really* zero?


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## ashappard (Jun 3, 2006)

Tex Gal said:


> Thanks Ashappard for sharing your knowledge. I'm sure it's helping a lot of people.


thanks, normally I lurk but I do feel for people struggling with spp.
the challenging plants are good for training. and each plant presents its own challenge.

its easy to tell people to examine their dosing, I've been told it several times by others when 
I had unexplained issues. "but my DC is green how can I have bad CO2" etc.

I sold away test equipment eventually, and now I just let the plants tell me how to dose.
simpler than it sounds, and it really does work.

rather than saying - person _x_ said that if I do _y_ - I'll be fine, and I'm doing that so whats wrong? I finally did start to really watch the tank and the plants and figure out what they need.


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## MrsH (Feb 22, 2009)

/\ /\ Wow - great stuff. Thanks a million!


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