sandbed/algae/nano issues - take your pick.

[christyf5]

So I suck at sandbeds and if nobody can diagnose this one, its coming out. I currently have a 7.5g Nano, one of those Innovative Marine all in one jobs with the LED lighting. Lack of sleep and caffeine make me forget the specifics of the name, I'm surprised I even remembered the brand name. Anyhoo, its been running since about August or so and has been a great little tank until a couple of weeks ago. I did a water change and the tank just hit the crapper. Its a zoa dominant tank with a pink hammer coral (for movement as it was looking a little boring in there) and a green favia which hasn't stopped being happy (tentacles out and lots of growth) since the issues began.

The problem started with some vividly bright green algae covering a portion of the sandbed, I'd say a 2x2" spot about 3 weeks ago. Then came the snot strings on some of the rocks and on the glass. The algae on the glass grows pretty quick and there are some coralline spots developing as well. All the zoas are puckered up tight and the hammer is not happy, it was the last to get really crabby about the situation. Favia is business as usual.

Since the issue I have done 2 water changes, one with new water and one with water from my 180g (done today). As I was doing todays waterchange I noticed that there were some pinky brown (beige? taupe?) sections on the sandbed as well, and they were hard. I'd say about 1/8" thick and crunchy. I ended up stirring up the sandbed some but haven't done any testing on the tank to tell whether the parameters are in check. I use the same bucket of salt on the big tank and do 20% water changes on it. The nano gets 50%+ water changes so bigger issue if there is one.

I use chemi-pure blue all in one filter media and thats all, I've used it since the beginning and I rinse it before it goes in. Temp is fine but like i say, haven't done any testing as the water is new and I test my salt buckets before I start using them and they check out fine.

Not really sure what to do other than haul out the sandbed. I thought I'd get a longer ride off this one before I had to do that. I don't have any luck with sandbeds, they start out nice and usually head south. Never figured out why. There are some brittle stars and a few bristle worms and some little snails that seem to get eaten by the bristle worms but all in all its a fairly happy little ecosystem until now.

Anyway, I'll stop typing and hopefully someone has some ideas.