Tank is crashing

Another water change yesterday. I've slowed them down to 5 gallons each time. My nitrates are down to 10ppm. Now I have red cyano starting on all the rocks. To say I'm already missing my diamond golby for his sand sifting ability is an under statement. He sure kept it looking good. As for losses, my monti frag I got from the last meeting is starting to get white spots and a little white on some of the edges. My son's favorite hermit died last night. He was our first hermit crab that we got when we started the tank and was about the size of a golf ball if not a hair bigger. I guess that's it for the update.