I removed my water tank some time ago.

id like to just throw the hose that fed into the stock tank, into a
smaller portable water tank I have handy, but the pump doesn't seem to
be able to pull the water up from it.

If I place water almost level with the pump and dang near submerge the
thing, then I can get it to pump, but its not easy.

how did the old system work, is it (in part) gravity fed?

Aka, do I need to somehow attach the hose to the bottom of whatever tank
I use and allow gravity to force the water into the pump before it will
start to take over on its own?

thanks!