Soilmaster Select.
I have some planted tanks here too, I was using Eco-Complete, which is an awesome product, but the cost will kill you! I heard good things about soilmaster select and I have it in a few of my tanks now and it seems to do the trick pretty well... would probably work even better to plant pond plants in!
![Cheesy :D](https://www.worldwidewatergardeners.org/forum/Smileys/smilies_smf/cheesy.gif)
It's cheap too, like ~$12 for a 50lb. bag... I filled my 75gal aquarium (48" x 18") 3" deep with it and I still have 1/2 a bag left. Much better than the $20 I paid for the Eco-complete that bearly filled my 10gal tank (10"x20") 2" deep!
It's made for baseball field turf, but alot of people have been using it in aquariums for a while now... I am a few months into my trials so far and no cmplaints!
![Smiley :)](https://www.worldwidewatergardeners.org/forum/Smileys/smilies_smf/smiley.gif)
Hardest part is finding it... you're not going to find it at Home Depot or Lowes, their primary distributor is Lesco which is a turf company. Look them up online and find one locally, they do ship, but then we're back to spending too much money again...