i bought a second hand visi-therm 300watt heater, no instructions, and never use one before
so the question is -->
1. what happens if it breaks? will the fish fry? what are the % likelyhood of the fish keeper being electrocuted!!
2. min water level mark--> do i need to turn it OFF if i change water and it drops below the min level?
3. i have seen pictures of heaters totally submerge, does this model work that way? if so can it be place flat /horizontal at the bottom?