Something is in my fresh water tank

[Bordway]

I was filling up my fresh water tank after sanitizing it and I see a couple of things floating inside the tank. I did leave the valves open overnight. I have flushed it several times but it is still there. Does anyone have an idea what it could be or how I could get it out.

 

[ppine]

I had a hybrid trailer once that had been in Florida. The water tank was translucent. I could see some plants growing in the tank. Large leaves even. I never drank out of it. Hard to get rid of.