First off, I have a 5 gallon planted aquarium with 1 male vieltail and 2 otocinclus. The betta eats hikari bio betta gold and kens premium betta crumble along with the occasional blood worm. The otos get shelled fresh peas and 1/4 hikari algae wafer but they seem to prefer eating the dietris from indian almond leaves, sometimes skinning a whole leaf down to its veins within a day. The temperature is between 78º and 82º depending on the time of day or the season. However the temperature change is very slow and gradual. The plants include elodea, thai rice patty plants, bamboo, japonica, java moss, marimo, and a 2-3 unknown plants that were gifted. I keep a buffered filter with activated carbon. When I do water changes, I use prime, stress zyme+, the entire seachem plant care system, ada nature aquarium, and black water extract. Also, occasionally I will add kordon fish protector and amquel plus ammonia detoxifier. I regularly keep 2 indian almond leaves in the tank as well.
About 3 months ago I added some elodea to the tank and soon after I noticed that the tank had small, slithery worms which my betta was eating. I thought they were planaria but have since identified them as nematodes. There were very, very few of them but I still vacuumed the gravel well and reduced the amount of fish food in the tank. Each water change since then has just "unearthed" more and more of them. I did an 80% water change yesterday because there was a carpet-like patch of the nasty things on the side of the glass closest to the lamp. Today I really am freaking out because there are WAY more nematodes all over the place but also I have hydra attached to my gravel, plants, and a few other surfaces and tiny, quick moving, ball-shaped parasites which I believe may be cyclops crustaceans. I also noticed a small snail out break which was seemingly not present before.
I researched a bit and I decided to order Panacur and Levamisole online because I want to get rid of this before it gets any worse. Are these pesticides safe to use in conjunction with one another? Is there a more effective way to rid my tank of these pests? Is there anything I mentioned above that seems like it may be contributing to the outbreak of these worms and how I can further prevent them? Are they adding any stress to the nitrogen cycle and do they cause ammonia spikes as they die? I read that the nematodes and cyclops are beneficial to an aquarium but there is SO MANY OF THEM. I think they may be what the hydra are eating to stay alive. I'm really worried about the hydra stinging my fish and that if I end up with a malicious pest in the aquarium I won't notice it amongst the rest of these things
. Any advice is welcomed, I'm desperate!