I am troubled by difficult to remove diatoms (algae) in my lake Malawi
setup. This is made worse by the fact that it is a big tank 6ft long 5ft
deep and acrylic!

Anyone any suggestions/tips on shifting these without scratching the
acrylic? I'm currently using a Kent pro scraper/mop but the scraper is
occasionally scratching the acrylic and the mop wont budge the diatoms!

Sorry I'm not the best expert, but aren't diatoms the ones that float in the
water, and give you green water, not the ones that coat the tank. Diatoms
can be got rid of by blacking the tank out for four days. Check your
phosphate levels as well. I caused mine a while back by leaving a carbon
pillow in too long, and it leeched loads of phosphates back into the tank.

A