Can't keep crabs, other mysterious problems...

[rwillden]

Well, where do I start...

I have an 80 gallon tank, with a 30 Gallon Refugium, and 10 Gallon Separate sump. It’s been set up for about two years.

I added a DIY Nielsen Kalk-Reactor that uses a “garden style drip” nozzle powered by a pump to deliver my kalk mixture at night to my corals, and to help keep pH up. Well, after about a month of running the reactor, I started noticing some interesting things going in with my system. I noticed that all my crabs were gone. It looked like a ghost town if you can imagine all the empty crab shells all over the place. I also lost my boxer crab, porcelain crab, emerald crab, and one of my two Cleaner Shrimp. All of these have been long-time residents of my tank. I have not lost any snails that I can tell, and I still have a cleaner shrimp that seems to be doing fine. However, my entire crab population is non-existent. I can’t figure out what the problem is.

My Alk at the time measured 2.75 Meq/L
Calcium was a little high at 505ppm
Salinity was at 2.023
pH measured about 8.2-8.3

Ammonia, Nitrate, and Nitrite all measured 0

I really am losing faith in myself to fix the problem without spending a fortune to overhaul my system.

The corals in my tank are doing okay… The Hard corals are doing fairly well, as they love the calcium, my button polyps are not doing well, and are all shriveled up, and there are a couple of SPS that aren’t looking as good as they used to.

My problem is I don’t even know where to start looking. I plan on doing a 25% water change tonight, to get off to a good start, but what to do next I don’t know.

Any advice is greatly welcome, and appreciated.

Thanks,
Ryan

 

[DOGMAI]

Usually people are trying to get rid of crabs.

Sorry I have no usefull advice for you I just couldent help myself.

I had the same problem with inverts in a small tank I had going they all just started dying. For me the problem was my salinity was way to high.

Still not useful I know so I will stop.

 

[Len]

The two main possibilities I can think of for the loss of your crabs are:
1) Something could be predating them, like a mantis shrimp. In my tank, crabs never live long with my resident mantis and hogfish hunting them.
2) A toxicity issue. Inverts are particularly susceptible to being poisoned (by metals, for example). This could also explain why some of your corals aren't looking as well as they used to. A series of large water changes (25-50%) will help dilute toxins. This is where I'd start for sure .... four big weekly water changes.

BTW, I believe you meant 1.023 for salinity, not 2.023. At least I hope so

 

[fishfanatic2]

Your Alk does look a bit low. I second Len on the toxic metals thing, but I think your corals would be gone also if you had such a thing.

 

[Bleeding Blue]

What do you mean by "garden style drip nozzle"?

 

[Anonymous]

could it be that there was a molting?

there are a lot of hiding places in an 80g for three or four crabs. are the three listed all that have come up missing?

 

[rwillden]

I mean all of them are missing... Like 20-25 Crabs...

The problem is self evident... I have hair algae forming everywhere.

The garden style drip nozzle I'm referring to is a 1/2 GPH Regulated Dripper nozzle that you buy at home depot for a garden drip system. I hooked it up to tubing from my powerhead, through a check valve, then through the reactor, and finally through the dripper. It's a really inexpensive dosing pump basically.

I did a 25% water change, and hope to see something positive start to happen... Could it be that I had a Rio pump with an exposed core or something? I just replaced both of those (a 2500 and a 3100) today as well. I got a 2400 GPH Mag drive with a SCWD Squid.

 

[shalegac]

What fish do you have, if any?

 

[NMreefer]

What does your iodine level look like? I've noticed that if iodine is low inverts have a tough time with life.

Agreed with other posters on the toxic metals also.


Phillip

 

[Bleeding Blue]

I wonder if there are any copper parts on this drip system. Maybe a spring or something that you cannot outwordly see. I am sticking with the heavy metal guess. Just my $.02.

Mike

 

[rwillden]

No metal parts in the dripper, it's all plastic, and is about the size of a quarter. It's clear plastic, so there's nothing in it. Also, I've checked my tank for copper levels. It showed 0 traces of copper.

 

[jmanz]

FYI

I am having the same problem and have a shell graveyard. BUT i just caught a mantis roaming on the bottom of my tank which I had never seen before. we'll see now that he has been caught if the next batch of crabs can survive

 

[Bleeding Blue]

Hmmm...well darn it. What do you use for top off water? Maybe it is something that you are adding there?


Mike