Joe's Low Tech 54L

[Spider Pig]

One note of caution with them is that the nitrate source is ammonia/um (can't remember which) however I haven't noted a difference in the amount of algae or health of fish. Apparently this is similar to Osmocoat which has been used by others with no ill effects in the past. Also remember that it is slow release and under the gravel so not as much of a danger. Managed to find the thread:
viewtopic.php?f=17&t=741&st=0&sk=t&sd=a&hilit=osmocoat&start=50

 

[Joecoral]

Actually I think there's some API root tabs in work, I might borrow some, I assume they're pretty much the same thing