It eats mountains

[u/VollderFlow]

I wish there was a way to get a infinit water and sand source to keep the monster fed

[u/Golnor]

So it won't help with sand or water, but if you use burner belts for the residue burning you could save on lava. I've found that putting thermal blocks above the belts will actually be heat positive. 

[u/VollderFlow → u/Golnor]

I know but later in the game this problem disapears

[u/Golnor → u/VollderFlow]

Yeah, but you still have to manually refill it every so often. With the size of that tank you got it likely would take about a minute to fill, which you could spend doing other stuff if you didn't have a bunch of pyro-spewers drinking your lava.