ya it depends wich 'foxtail' you are talking about.
Myriophyllum or Limnophilia (I've seen both refered to as 'foxtail' on ebay or such, mostly its myrio tho) are very hard to grow. They need lots of light and CO2 addition.
Ceratophyllum (AKA Hornwort) is VERY easy tho. It tends to like to float and has no roots. This one I owuld recomend for a first time tank. Will grow well in most anything and if given lots of light it will grow like crazy!
As to Jungle Val it will get prity big for a 15 gal. I have a version of jungle val and it seems to stay smaller in the 15 gal than it does in the 33 gal but its still big. I think a regular straight leaved Val would do what you would like and look a little beter proportioned.
Just so you know at one waterchange I took a Vall leaf out of my 33 gal tank that measured TWICE (and then some) my hight (5'10) and then still had nearly 2 feet to the tank and the botom of the plant!! The leaves on the top of the water was a twisted tangled mess to most people but I liked it. and so did my SAE who would rest on a leaf and bearly have to move a fin to stay there near the surface.
Neadles to say not much light reached the bottom of the tank untill I recently trimed the Vall back to 2 feet. ;P Some of the leaves also reached over an inch in width, with most of them being between half an inch and 3/4ths. I've also found that my Jungle Vall grows very very slow compared to others, reproduction wise anyways. I still only have less then a dousen plants.
I'm thinking of getting some regular Vall for the smaller tank.
