Ok. I have noticed some of my could are not opening up all the way. They started this towards bedtime last night. But here's the kicker. It's only my pulsating xenia, zoas, and my plate. My mushrooms and frog spawn are looking better than ever. My phosphate is 0. My nitrite is 0 ammonia is 0, ph is 8.2, dkh is 10 and calcium Is low. Is the dkh what's causing this sudden change or is it something else? The diatoms are going away and I run 3 175 watt metal halides. I did change them to 20 k from 15 k. Would this cause a change? Or should I try moving them around?