Two sudden deaths, why? And is my surviving crab in danger?

[tiffiny.gibson]

Okay, so I'm very new to this forum but don't know what else to do. I noticed that two of my crabs were dead in their tank today. One was completely out of his shell in the pool of water. His shell was upside down as if he crawled out, and I'm 100% positive he's dead. In panic we looked for the others and under a hiding place Sheldon had shedded his skeleton but he was dead inside his shell, again we're 100% positive of this. Our third ans biggest crab, Sabastian looks to be healthy. He has successfully molted once and has a reddish brown color skin. I'm concerned though because his eyes are very red and he has not had red eyes before. Note: unfortunately we had dug up Sheldon and Patchy (the two dead crabs) about a week ago. I did not want to but a mysterious black vein like looking mold had begin to grow from the bottom of their tank and I was worried it could kill them so we dug them out and immediately cleaned their tank. Sabastian (remaining crab) was not barried at this time but when we put them all in a box together while we cleaned the tank. Patchy began chirping aggressively and Sabastion was on top of him. So I separated them and put Sabastian in his own space till their tank was ready. Their tank is a 20 gallon tank with at least 8 inches of play sand. I did not moisten the sand because I wanted to put the crabs back in. I have at least 20 different shells ranging in sizes and have multiple hiding places as well as a fancy climbing set up for them. I have two tupperware containers with little rocks in them for their waters. I provide them with all kinds of foods to keep them healthy and normally they are very active and are roaming around. I use a heat lamp and we mist multiple times a day and keep a gauge in there. Lately we have slacked on turning the light on I will admit but we have turned it on at least a couple hours a day. I've had them for about 6 months and they seemed so happy and healthy. We don't have a lid at the moment though. Is my biggest crab a bully? Did I over stress them? Also a side note. I used to have them on a 10 gallon for the first 2 months I had them and I had a fourth crab, Squirt. He died but we only found his shell and one claw under the sand. I assumed he was eaten by our biggest crab because he was very very tiny. I just feel so bad and they were my babies and I don't want to loose Sabastian too. Is there anything I can do to prevent him from dying. Also do I need to get him a friend now that his tank mates have died. I don't want him to get lonely but don't want to get more crabs if I'm bad at caring for them. Any input, knowledge and advice would be appreciated

[Hermiesguardian]

I'm so sorry for your loss. Sounds like most of what you are doing is good. Just a couple of major things. You need a lid. There is no other way to keep in heat and humidity. They need at least 80% humidity to breath. They have modified gills. Spraying so much can lead to flooding. The temp should be a minimum of 75° but they are more active at 80. A digital gauge is more accurite than the analog. If you don't have a lid you can just seal the entire top by taping down a garbage bag over the top. They will get air when you feed them. And without humidity the substrate will dry out. Spraying only wets the surface. The entire substrate needs to be sandcastle consistancy or it won't hold their tunnels and caves. Which is imperative to molt. Before you add a friend to the tank make sure these conditions are corrected.

[curlysister]

Agree with the lid/ cover being essential. I didn't have a lid on my first two tanks, I just taped Saran Wrap over the top, and vented it a little in a corner as needed to keep the humidity at the correct level. Many of us mix in Eco Earth with our playsand, a ratio of one part EE to five parts sand. Mix it together and add dechlorinated fresh or salt water until it is the proper consistency.
If you have the tank in a room with a window, they will get daylight naturally, so isn't a huge deal that you hadn't turned the light on consistently.
What do you use to treat your fresh and salt waters? What brand of salt are you using?

[tiffiny.gibson]

So after researching I've discovered the errors of my ways. In the panic of cleaning their tank and getting them new sand, I did not moisten the sand to sand castle consistency. I believe since I interrupted their molting process and did not provide them with adequate moisture to dig their tunnels, they died on the surface. I'm still very upset over it but it's helped me realize what I've been doing wrong. I have been using a heat lamp and misting. But have had an open lid. So I am putting In eco earth and adding new climbing toys. Also switching to using instant ocean with chlorinated water instead of using the bottles of salt water from petco. I'm also gonna build him bigger pools. I'm in the process of moving so I'm moving him to a 30 gallon sized plastic tote because I don't want to deal with moving this big tank. The tote is actually 10 gallons bigger anyway. Once I get all set up a d get Sabastian settled in, I'm going to adopt a hermit from a sanctuary here in Portland. I'm sad to have lost them but I'm thankful to be fixing ny wrongs.

[Hermiesguardian]

You'll have happy crabs! Keep us posted. Post pics when it's done. We love pics.

[curlysister]

It is only recommended to dig up crabs under extreme circumstances like a flood or a bacterial bloom. If either is suspected, you can come on this forum and ask for advice about whether to dig or not, and what to di with the crabs if they are dug up. If a crab's molting cycle is interrupted, it can have devastating effects. They would not have dug back down, even if the substrate was the correct consistency. They would need to be isolated in perfect conditions, and even then may not survive.

There is a tutorial on this site about how to make a crabitat from a tote. I don't' use one, but check out the tutorial for really good info.

The brand that is most recommended for treating water is Prime. Both the fresh water needs to be treated, and also the salt water needs to be made from treated water.