dried cement like coraline removal hints

[lockrookie]

all is scraped off but i think some is embedded in the glass. for what its worth i appreciate all the ideas and help.

all in all i think i have decided the use for this tank im going to use it to mix salt water and i am going to build a closed loop for mixing. one thing ive noticed when mixing in a rubbermaid container it the sediment that builds on the bottom of the rubbermaid container which then flakes off and contaminates the fresh mixed water with white flakey particles. any ides how i would keep this from happening. ive thought about very high water presure shooting at the bottom of the tank but unsure if that would be enough. all i know its a bugger to clean when it builds up.

sorry to switch the feel of the thread i call it multiple thread personalty syndrom.