Hey there. In my 200gal tank I have 2 metal halide lights that give off a ton of heat, this results in a huge water loss. I add about 5 gals of new water every 2-3 days. Is this normal and if it is do i have to do water changes as often. I know I should do a 20% water change every week or so but because I'm adding new water (10-15gals) every week do I need to do such a large water change.