HCA: Hermit Crab Association

Hi, team!
At long last (!) I'm beginning a ninety gal. build. I'm picking up the tank tomorrow. My little dudes are finally going to have decent housing. Tres woo-hoo!!

I'll start with just the tank itself & about a foot of sand. Later I want to add a topper.

My first question concerns the false bottom: I've read several false bottom threads and have now thoroughly given into indecision.

It's a lot of sand.
If a crab gets under there, it's a lot of sand to dig through. But a flood could be monstrous. Because I experience bouts of intense lethargy I'm concerned that if water starts to collect at the beginning of one of these bouts, I won't have the energy to deal with that volume of sub in time - removing it, drying it out, replacing it. Suctioning it out may be more do-able.

Can someone talk sense to me?

What were your rationales for addin/not adding falsies, which explanatory links did you find most helpful?

I'll add pics as soon as I have them!

Congrats!

I never have done false bottoms, but after this much time and several floods due to my stupidity at the start I've got a good feeling for how substrate reacts.

Crabitats are closed systems so there will never be a flood so long as you keep track of how much water is going in. Keep it slightly on the dryer side from the start and the mass of sand in a 90 gallon tank can easily handle a spill of several gallons without any standing water at the bottom.

I think there is a tendency to go too wet from the start which compounds problems. I usually do 1/2 to 3/4 gallon of water (like baking, humidity and how the sand was stored has a huge effect on how much moisture is needed) to a 50 pound bag of sand, and so long as it's fluffy and keeps it's shape it's good to use. Rarely will I add more than that. Also, the directions on EE will give you soup. I go with half the water they say, hot water, and seal the bucket with plastic wrap. In a half hour it will be fluffy and moist, but won't drop when squeezed. If you want to do a mix of the two, use the full amount of water for the EE and once it's expanded add it to a bag of dry sand, adjust from there if needed.

Starting with moist but not overmoist substrate will mean any spills gets absorbed. It's always easier to add more water than take it away. If it gets too dry I throw a couple of cups on the surface and let it soak in, but these days I always err on the side of slightly dryer.

wodesorel wrote:Congrats!

I never have done false bottoms, but after this much time and several floods due to my stupidity at the start I've got a good feeling for how substrate reacts.

Crabitats are closed systems so there will never be a flood so long as you keep track of how much water is going in. Keep it slightly on the dryer side from the start and the mass of sand in a 90 gallon tank can easily handle a spill of several gallons without any standing water at the bottom.

I think there is a tendency to go too wet from the start which compounds problems. I usually do 1/2 to 3/4 gallon of water (like baking, humidity and how the sand was stored has a huge effect on how much moisture is needed) to a 50 pound bag of sand, and so long as it's fluffy and keeps it's shape it's good to use. Rarely will I add more than that. Also, the directions on EE will give you soup. I go with half the water they say, hot water, and seal the bucket with plastic wrap. In a half hour it will be fluffy and moist, but won't drop when squeezed. If you want to do a mix of the two, use the full amount of water for the EE and once it's expanded add it to a bag of dry sand, adjust from there if needed.

Starting with moist but not overmoist substrate will mean any spills gets absorbed. It's always easier to add more water than take it away. If it gets too dry I throw a couple of cups on the surface and let it soak in, but these days I always err on the side of slightly dryer.

How do you tell if you have a flood and what causes it? I use gallons upon gallons of water to mix my sub. Now I'm worried.


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Because I err to the drier and use straight sand, there is a difference in color when it starts getting too much moisture added.

However, in 5:1 tanks or for those west of the Rocky's who have naturally darker sand there is almost no way of knowing unless you get into the tank and find standing water or soggy soil. By definition a flood would be standing water at the bottom which you can sometimes see as a layer through the glass, but it can also mean super saturated soil that is like a mud pie. That can still occur with a false bottom if water is not being removed when it collects.

The number one way to tell if it's being kept too wet is of you ever have to dig and you get blasted in the face with the smell of methane or rotten egg. This is anaerobic bacteria, and it is very bad. You may also see discolored portions of the substrate that this darker, in straight sand these areas will be grey or almost black. Unless it's really bad, these areas form away from the glass, in the very middle of the substrate mass where there is zero light. They tend to form in pockets of organic matter (cocofiber, buried food or piles of poo) and grow from there, they need a lack of oxygen, moisture, and lack of light. Supersaturation gives them all of this. They release methane gas (deadly) and also create acid as a waste product.

JMT and I still do and recommend at least yearly substrate changes (he always said 6 months, but I'd kill my back doing that) and this is one of the reasons why. I know the trend is to make substrate and only add to it, but a giant mass of sand does not behave like a fish tank where you get biological filtration that can reach every area. Sand is static, it doesn't move in its own and unless your tank is very overcrowded the crabs are not going to be mixing it enough to aerate it. It's a closed system so things being added to it are going to break down but stay right there. Replacing 1/2 to 3/4 on a regular basis helps keep bad bacteria under control, introduces oxygen to the bottom, removes anything that may be building up over time (like salt from spills, or waste) and allows the keeper to keep an eye on what is going on. Had I done mine on time I would have caught those stupid ants before they did as much damage.

Bad substrate is a top killer.

The tank I just built has a wooden bottom that you can't see through. I thought for a long time about adding a false bottom, but ultimately decided not to. In my 8 years of crabbing before, I never needed one.

I don't over-saturate when mixing my sub and I'm careful about adding any water to the tank. With stable conditions, I don't have to worry about misting or anything for humidity and my pools are glass loaf baking pans sitting inside of a shallow glass cake pan (so no worries about leaks).

I mean, if it gives you peace of mind, go for a false bottom, but in my opinion they aren't needed - just monitor your conditions and be mindful of adding any extra water to the tank.

Congratulations on the upgrade! I'm really excited for you!

I personally don't have false bottoms in any of my tanks. I also have never had an issue with flooding.

I think it has to do with what makes you feel comfortable. I have seen one thread where an experienced crabber had a crab get through her false bottom. If using a system like a fogger or a waterfall, I would probably consider it. To each's own.


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Congrats on the upgrade!

I too have never used a false bottom. I have a 125G with 40B topper and a 120G bamboo tank. I had a 90G set up as well but have recently taken it down.

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It didn't happen last week because complications... but now I'm going to go pick it up. Tomorrow. I hopeihopeihope.

Man, this tank is just not happening. The guy who offered to sell it to me is really bad at communicating, and keeps bailing on plans for me to pick it up.

Anyhow, back to looking for a tank! I'm sure I'll find one eventually!

That's a bummer! If you were closer, I'd give you mine. I wish you the best of luck

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Don't give up hope! Are you on Facebook? Try reptile buy/sell/trade groups. I got my 90 with stand for $75 because it had been sitting unsold for a few months and the kid didn't bother to list it anywhere else. There are also aquarium groups but I've never been to know how their prices are by comparison

BACK IN THE GAME.
Just brought my 90 gal home! Feels SO good.

I need something to put it on, and to get some acrylic cut to size for a lid. Already have a little over 6 bags of sand.

The aquarium forum suggestion was a great one - the chap from the GTA aquarium forum I got my tank from was really a lovely fellow.... and had a LOT of tanks. Holy moley! He had several really large tanks that were just sitting empty & his wife wanted them gone.
I got my 90 for $90.

Verrrrrry happy.

Awwwwesome!

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LadyJinglyJones wrote:BACK IN THE GAME.
Just brought my 90 gal home! Feels SO good.

I need something to put it on, and to get some acrylic cut to size for a lid. Already have a little over 6 bags of sand.

The aquarium forum suggestion was a great one - the chap from the GTA aquarium forum I got my tank from was really a lovely fellow.... and had a LOT of tanks. Holy moley! He had several really large tanks that were just sitting empty & his wife wanted them gone.
I got my 90 for $90.

Verrrrrry happy.

Yay! That's awesome! I love it when people give you a good deal! I saw a 55 gallon for $17 at a thrift store yesterday. It was sooo tempting, but I have no place for a second 55!

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Say what?!! Awesome!! I totally missed this post! Have you got it set up yet? Can't wait to see it!