Stunted sword plants?

[Pictus]

So I have had these two sword plants for about a year and they are still so tiny. I got them at petsmart so they were grown out of the water. They melted and came back but haven't really grown since. Originally I had them in a gravel based aquarium (with root tabs), but that one sprang a leak so I set up this new tank a month ago. I have an inch of soil and three inches of sand. In the last month since moving them I've noticed they have a lot of bushy growth at thier base but are not growing up and out. I feel like everything I've read on the interwebs doesn't apply to my situation. They all seem to address the melting back process or not enough nutrients. All of my other plants grow like mad and I'm trimming them once a month. 75g with fluval planted light bar, also some natural light. 80°F water temp. Dose weekly with aquarium co op plant fertilizer. CO² setup. No alagea on leaves.

 

[Byron]

All (most anyway) species in the genus Echinodorus (sword plants) can be variable depending upon their environment, which includes light and nutrients. Aside from this, there are some that remain on the small side. I have had what was initially called Echinodorus bleherae grow leaves more than 12 inches, while others (from the same parent plant) remained around five or six. And everything in between. The phylogeny of this genus is part of the reason.

Why is the water so warm, at 80F? Are you using substrate tabs--this plant really benefits from these, depending upon the type.