I have a pressurised hot water tank. Can I fit a shower pump?

The title says it all. We have a pressurised hot water cistern. We have ok water pressure for our shower but are about to install another 2 and wanted to make at least one a very powerful power shower. Can you pump water from such a cistern?

thanks in anticipation

Not successfully. Better upgrade your tank/pump combo if it is not strong enough.

The tank is only 2 years ols and would cost 00's to replace.