I don't want this to sound like I'm arguing, because I'm not, just trying to help you with the problem. I also have no idea how long you've been into aquariums, so not trying to treat you as if you're a newbie either...
Don't worry about
discussing stuff.
Us aquarium types will discuss anything and everything from test strips, to floating bags of fish, to how much light what plant needs or don't need, etc. into the ground. Then wake up tomarrow and do it again. So, no problems their.
I've been around fish off and on for a bunch of yrs. But I'm still a newb with this kind of stuff, because I've pretty much always had 1 tank at a time. And seemed to do things, for the most part. Good enough to stay out of trouble. And/or the lucky thing.
My first tank was somewhere around 38 yrs ago. A 10g from my brother with a couple of goldfish. They lasted maybe 3 and 6 months.
The next one came around about 19 yrs ago. A 29g that me and then wife, would take outside about once a month and clean, inside out, AND the gravel.
Finally, at a mom n pop type(1 guy) LSF. I was talking to the guy and said to quit doing that and handed me a pamplet. thats how I found out about the nitrogen cycle.
2 or 3 weeks later I bought a 75g from him. And had it sitting in the middle of the room on the floor when my wife walked in, said "I aint cleaning that!" and kept going. I just laffed and said "Me either!"
Ended up with 70 something fish in it. And was doing fine until I tore it down to move it out of that house.
=======================================================
Ok, back to the problem Hydras. And nope never ever saw before in my life until a week or so ago, when I thought they were hair alge starting up.
From that link up their...
They can be found in most unpolluted freshwater ponds, lakes and streams in the temperate and tropical regions by gently sweeping a collecting net through weedy areas
Sounds like my tank. Really!
I ran the Hit Magnum with a gravel vac attached to it today. Right before that last post I made.
There wasn't much of anything to clean up. The most I saw was when I stuck it to the clump of Java Moss I got about a week and a half ago. It could have had some hydra on it? But, that would be kind of hard to find on moss. But really its the... I have it now what stage. However it got started.
Oooops just looked at the clock. Gotta go for now...