D,
nice puffers.
they won't eat snails huh? have you tried different snails? some have toxins that make fish know they are not tasty.
I suggest the malasian trumpet snail, not only a good little live bearer that won't over run your tank, but they like black algae, a plauge that you look to be suffering from (I have too, once you have it, it's nearly impossible to get rid of unfortunately.) oh, as far as I know, puffers prefer round snails to horn type snails (both fortunate and unfortunate, most round snails are plauges in the planted aquarium, and the horned snails you should put in there for your plants they may not eat.
Anyhow, Puffers like to put the whole snail in their mouth before crushing it. Are the snails to big for them? maybe if you got a smaller group of snails?
I would advise putting together a little tank with some round snails, a little filtration and an airstone, and then throwing in something like a little piece of cooked shrimp for the snails to eat.
When you start seeing little snails that seem about right for feeding, take a couple out and feed them to your puffers... be careful to make sure they eat them, the last thing you want of course is a bunch of snails ripping though your pretty plants!
I don't think your anubis will set seed underwater, if I remember right, in nature anubis is a shore plan, existing both above and below water, meaning it probably get's it's flower above the water.
You might also want to get a siamese algae eater (not a chinese) but a siamese, they like black algae and black hair algae as well! awesome little fish.