Missing Mushrooms and Zoos!?!?!?

[FxdupCobra]

This is about my girlfriend’s 30 gallon reef tank:
At first I thought something might be eating them like my missing peppermint shrimp or the hermit crabs (I did see a large black crab that only comes out at night). I did a water test and here were the results:
Salinity: 1.022
Temp: 79
Amn: 0
Nitrite: 0
Nitrate: 0
Alk: 1.8 (needs to be 5.0 - according to my salifert tester.)

Could it be the Alk? The mushrooms and the zoos went away slowly lesser and lesser each day.

Any information is more then helpful.

[Tammy3770]

(I did see a large black crab that only comes out at night).

this is what is doing it.
I have the same problem in my tank.
I've been chasing it for a week now,
no luck yet.

[FxdupCobra]

You honestly think its the crab? He is about 1/4-1/2 an inch he is black and has some gray/white/silver on him. I should try to catch him.

The Alk is not the problem at all?

[iaJim]

http://reefcentral.com/forums/showthread.php?s=&threadid=751573

Is he like this crab?

[Tammy3770]

yes you should adjust your alk,
but I don't think mushrooms and zoos will rapidly decline because of it.
plus you would describe it as "melting away" not just disappearing.

lets hope it is your alk, that is easier to correct than the crab problem.

[FxdupCobra]

No thats not him. He is more blackish/gray. But either way I believe I have to get him out!!!!!

[miztic]

The salinity should be closer to 1.025, wouldn't surprise me if thats part of it too

[FxdupCobra]

Here is the pic of the crab which I got out of my GF's tank. Is this the problem?!?!? Could this guy have ate the polyps and the mushrooms.

http://reefcentral.com/gallery/data/500/88128crab1-med.jpg

[reefpimp#1]

I would say yes. look at the picture iaJim put up, it has the same marks and designs just a different paint job :)