I was told that I should buy a brittle sea star for part of my cuc and that is should be hardy enough to toss in. I'm having a bit of a chaotic chemical problem in my tank. Due to me having started with tap water and then switching over to ro water recently. I am reading .25 on my ammonia ( lowest number can be read on my kit) 15 on the nitrates and .5 on the nitrites and 5 on the phosphates. Do I need to hold off the brittle or is he hardy enough?