I have had no luck with rotala walliichi or red cabomba. Both slowly lose their fine leaves until all that's left is a blackish stem. I get the occasional shoots of new growth, but they don't really take off. My other plants, mostly slow growers, do just fine.

I have 196 watts of compact florescent on a 58 gallon tank, dose EI with tropica micros, run pressurized CO2 and have a drop checker (with 4 dKH water) reading yellowish green. Circulation in the tank is excellent. Rotala indica grows like a weed, as does moneywort and valisneria.

So... maybe it's light, but I kinda doubt it. I run a 9-hour full-on lighting schedule. The tank gets some light from a window as well. I'm at my wit's end with this and won't try any delicate reds again unless I've got ideas for what's killed them in the past.

So what might it be?

Likely CO2.
Both are very rapid easy to grow weeds for me.
I'm talking inches per day of growth.

Try good current EI, ADA AS, good light etc.
They are not difficult plants.

Regards,
Tom Barr

I have the exact same problem. Have tried both plants seveal times. Everything else I have tried I can grow like crazy. I think CO2 ext is good in my tank, but I do have hard water.
JR

Well, it does seem to like softer water.
We have soft water here and grows great.
KH up to 5 ought to be okay.

Regards,
Tom Barr

I've kept both of these plants in my fairly hard water (9-12 dKH) ARLC tank, although they did not do well until I planted them in small patches of ADA Aquasoil that I made in my otherwise alkaline substrate. Cabomba especially seems to be sensitive to substrate alkalinity and only seems to respond well when planted in an acidic substrate like Aquasoil. R. wallichii and R. sp. 'Viet Nam' would grow in my regular mix of gravel but did not do well until I placed them in their own little bed of Aquasoil. And of course steady CO2 supplementation is key.