Can you hose from a flexitank?

I managed to get a 2nd hand flexitank for pretty much free it's the big 400l version

I got this with some second hand LEDs and green man system I snagged up for dirt cheap but I dont want to go hydro infect I'm already too deep in soil to go that way

I've ordered a hose online but it's not managing to pull anything from the tap on the bottom of the tank, I've checked the hose the whole way through nothing is blocked and the water is just leaking through the hose instead of being pulled through

So I'm guessing I need some kind of pressure to push the water through the hose? How can I get around this

If I have to continue bottom feeding with a jerry can I might cry!
 
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