I have a frogspawn that back when it was 2 heads I put one in my 29g and the other in my 110
the one in the 29g became light green with white heads and the one in the 110 has much richer colors; a much deeper green with purple tips. The one in the 110 now has over a dozen heads and the one that was in the 29 only has 2.
I have since moved the one from the 29g to the 110 and it's starting to morph it's color to look like the other one. From these moves I can conclude that water condidtions, feeding and or lighting will change the colors in a frogspawn. I'd be speculating on exactly what caused the changes.
the 29g has T5 lighting but mostly white spectrum
the 110 has RB LED.s and a mixture of T5, over all teh lights are more intense in the 110
I use the same salt mix and both tanks get a ~15- 20% water cahgne every 2 to 3 weeks
The 110 does have more robust water flow, skimming, dosing of kalc and use of a Ca reactor where on the 29g has a HOB skimmer and I never test or dose anything. Both tanks are very healthy with a robust bio diversity
The 110 gets fed pellets, cyclopsee and mysis where the 29 only gets pellets