I'm not sure what you mean by "Safe". I've had in my pond, Duckweed, riccia, cabomba, ambulia, indian fern and crypt. pontiderifolia (Or something like that)
No, don't get a filter, get a powerhead. Petplanet.co.nz has Seios for a good price and my couple have been pretty good. A pair of M1100s would be $120 and give you a total of 8800 lph.
Phosphates at that level are not harmful to fish. They can be MUCH higher before they care. Other than it encouraging algae growth, in FW you can basically ignore it. I'd suggest testing your ammonia, nitrite and nitrate. THOSE are the ones you need to pay attention to. Especially in such a small tank.
As long as the current isn't hitting the surface it won't create waves on the surface. But...Why would you not want to create waves on the surface?
Also, I don't think a wavemaker is really necessary compared to just a simple powerhead. Most FW fish come from rivers where they have continuous currents, not varying.
Corn syrup is generally claimed to be more unhealthy than plain sugar. And brown sugar is essentially sugar before the molasses is removed from it. Many are just sugar with molasses added to it. So, similar unhealthyness.
Gimme some sugar, baby... :lol:
No, that's tempered glass. Which is stronger and harder than non tempered but shatters into small harmless pieces rather than giant, sharp dismembering blades.