Holding Tanks

[Wino]

After several years use our holding tank has 3 or 4 inches of 'solids' on its base, much of it caused by a calcium build up from the hard water in this area This build up is causing problems on pump out.
The tank is a Vetus plastic one, so its virtually impossible to get a hose to the end beyond the baffles.
Rather than all the expense and trouble in removing and replacing the tank I wondered if anyone knows of a chemical that could break up this human/calcium build-up to enable us to pump it all out?
RojM

 

[johnwest]

When I lift every year I remove the scaling from my shafts and props with brick cleaner from the local builders merchant.Fill an empty washing up liquid bottle and dribble over the scaling. I do wear rubber gloves and overalls as it is acid based, but it is very quick and effective. Rinse well with fresh water afterwards.

j