Round worms?

[hyperope]

So I got bored today and pulled out my old microscope I bought at an epa surplus sale. Couldn't find the separate list source so I used my phone. I extracted a long piece of green hair algae (cleanup crew has been called, but not shown up yet) and put it on a slide. Under there are many of these small roundworms (not tins) amongst the algae. They are colorless and has what looks th be a forked tail (maybe mouth). Also a few amoeba looking fellas rolling by. Any idea what the little worms are or if they are harmful? More little anemones have popped out of my LR. I am kind of using them as a Guage for water quality. All ok except high nitrate. My biocube filter is very nasty and I should receive new ones soon.alao have one orange polyp and have counted two small snails cruising around. Having a blast with this tank and I don't even have fish in it yet.