Plants do go through a period of adjustment when moved, as the water parameters, nutrients and lighting will almost certainly be different from their previous tank. I sometimes see this when I move a plant from one tank to another. Stem plants (like Rotala) being faster growing will show this quicker.
Having said that, I agree with Alasse on the lighting requirements, and a single T8 tube over a 36g tank is low or at best moderate light.
The other thing I spot here is your addition of a liquid carbon supplement (Excel) but no mention of the other nutrients. The Flourite substrate will not suffice, I found this out when I used this in one tank and I still had to add liquid fertilizers just the same. Stem plants take up nutrients via the roots and leaves, so the fertilizers should be added as liquid to the water column. Nutrients also occur from fish foods and water changes, but these are not likely to be sufficient in most situations for fast-growing plants.
And on the Excel, I would not recommend this given the moderate light and the absence of the remaining nutrients. The lighting and nutrients must be balanced, and for the plant species, as not all are the same in their needs. With low/moderate lighting, you should not be in a situation of having much of a deficiency in CO2, which mainly occurs from the breakdown of organics in the substrate. This should be sufficient to balance here. But I would suggest the basic liquid fertilizer, such as Flourish Comprehensive Supplement first, since you are familiar with the Seachem line.
Byron.
