So I have been preparing this pico tank for some Zoas and Xenia’s and was told by the aquarium store guy to focus testing on phosphate. I purchased a Hanna’s ultra low range phosphates detector and found my tanks phosphate level would drop despite any number of water changes. So I tested my plain tap water and found one phosphate level of 0.68 ppm and another above 1ppm. I live in Minneapolis and did some research to find that the city puts phosphates into their 100 miles of cast iron pipes to prevent corrosion or leaching of heavy metals like lead into the drinking supply. But I also found that only below 0.05 ppm of phosphates is considered safe for drinking water. Should I be concerned? I’ve been drinking this water for most of my life. This explains why I had such trouble keeping things alive in my previous tanks. I solved the problem for now by using some bottled reverse osmosis water that has 0.04 ppm phosphates, and I was able to get the aquarium down to that 0.04 ppm level after many water changes. Will not be using my tap water for aquariums again and am considering switching to bottled to drink or getting some type of filter. Will any type of water filter for drinking remove phosphates?