[Matt Nace]

I emailed Schultz about their product. He replyied quite quickly and didn't reccomend it.

Here is his reply.  

"Thank you for writing. This product would not be appropriate for use in an aquatic environment. The iron would quickly oxidize and be unavailable to the plants, and could harm the fish. I would stick with the plant food spikes and tabs for your aquatic plants.
Urea is simply another form in which nitrogen can be supplied to plants. It is typically a slower release form, requiring soil bacteria to break it down into nitrate nitrogen form that plants can use. That is another reason it would not be appropriate. In the anaerobic environment, it is doubtful this breakdown would occur with any efficiency.
Thanks, though, for your interest in Schultz products.
Robert
Schultz Company"

Only problem I see is that plant spikes use Urea nirtogen, and they breakdown fine. But this may be because this is liquid, and the spikes are solids.

Anyway, I suppose I can buy in bulk so the price eventually mkes the bulk price a good deal. In bulk I mean by the gallon , instead of in ounces(ml)