HCA: Hermit Crab Association

Looking into becoming a crab owner and wanted to ask some questions I couldn’t find the answers to while browsing online. It’s probably a bit ambitious for a complete newbie to DIY pet care, but I really want to set up a paludarium for my future crabbiness.

Some basic questions first, I’m basing my questions off of this setup guide: https://www.drsfostersmith.com/pic/arti ... cleid=2386
Sorry if these are super redundant and have been answered over and over..

1. Tank top: Currently I have this tank: http://www.exo-terra.com/download/high_ ... rarium.jpg ; However I read some things that seem to suggest a glass top is better for heat retention? More clarification for that would be appreciated!
2. Fluorescent strip light with full spectrum bulb? Is this different from lights/bulbs bought at the hardware store?
3. Best substrate: I’m planning to go about 7”-8”, not sure if sand or coconut is better. (coconut has a gnat problem apparently? But I don’t want crabs to get buried alive either!)
4. A good hygrometer brand? Looking on amazon, so many of the top selling thermometer/hygrometer combos have a low accuracy for humidity reading.

DIY! Questions (halp)
So I have a fairly large tank, not sure how many gallons exactly and would like to make it into a paludarium. Going to use this to make sure its waterproof first: https://www.amazon.com/Aqueon-Silicone- ... B0002ASD34

5. I want to separate the front 1/3 and fill that with salt water. I believe its 1 tablespoon of ocean salt to 3 gallons of dechlorinated water?
6. Since it’s not going to be a removable pool, I probably would need a filter wouldn’t I? (Will turn it into an L shape if I do, would like to hide it in the back.)
7. Would I still need a bubbler for the fresh water bowl? (That’s going to be removable.) And for the sea water for clarity’s sake.
8. Plexiglass seems to be the most recommended for dividers but uh. Local shop’s website: https://www.tapplastics.com/product/pla ... ze_plastic (I.. don’t know what the difference of any of these are...)
9. Could I use these: https://www.amazon.com/Assorted-Decorat ... =Sea+glass as an alternative and glue them together using the silicone sealant? I would prefer this over plexiglass personally, colorful wall and I can control the shape of it easily. If I don’t plug all the holes, substrate can be moistened that way? (Substrate needs to be moist right?)

Other things needed: Ceramic Heat Lamp, Ultratherm UTH (on side or back), climbing stuff (no drowning allowed in my tank!), shells...

Answers very much appreciated! Thoughts and suggestions on another methods or anything I missed?

Hi there! I know that people here usually don't suggest built in pools due to potential flooding. They break pretty easily, unfortunately. I think it's the salt mixture that wears away the silicone easily or something?

For the top, I would suggest a solid top! If you're looking to add a uva/uvb, then make sure you still have screening to put it on because it cannot penetrate glass.

I have problems with not being able to keep humidity in the tank with mostly sand. If you want more stable humidity I would suggest a mix of more eco earth than suggested when mixed with sand.

For a temp and humidity gauge, nearly everyone here suggests accurite (I think that's how you spell it)

Hopefully we can get some other people's answers in here! Good luck!

Hi! Welcome to the HCA!

One thing I wanted to mention is that we do NOT agree with putting UTHs under the tank like Drs Foster and Smith recommends. two reasons - with the substrate depth that we recommend it creates a fire hazard. The second reason is it can cook the crabs. As crabbers, we want to heat the air, so we put UTHs (Under the tank heaters) on the back or sides of the tank above the substrate.

I personally prefer glass lids myself. However - you cannot use heat lamps with them - they will crack the lids. You don't need heat lamps if you get a good UTH - I personally like the ones from www.reptilebasics.com or www.beanfarm.com Heat lamps also make your humidity evaporate a lot faster.

I use instant ocean - it is 1/2 of a cup per 1 gallon of water.

Bubblers are needed for both pools.

The built in pools are known to break down over time - I can't remember the reason - but the plexiglass/glass/doesn't bond really well with silicone and or the salt breaks it down over time. They usually last awhile before it happens. When it does break down though, you will have a mess on your hands and potential deaths if anyone is molting. I wouldn't recommend it.

Yep, silicon will not bond to already dried silicon. Built-in dividers always end up failing due to there being existing silicone from when the enclosure was originally made! It can take a few years, but leaks into the substrate will flood or make it oversaturated which leads to the death of molting crabs. Plexi is definitely out as the oils in the plastic break down the silicon and when it fails it tends to do so epically.

Hermits are challenging, since they require not just proper conditions on the surface, but a well-maintained very deep amount of perfectly moistened substrate. They'll be spending two to three months at a time at the bottom of that mass of substrating molting, and depending on size may end up repeating that three or four times a year. With all other humid loving species all you have to worry about is what is going on up top!

So glad I asked here before I bought anything.

So from what I understand is that no, don’t use silicone to waterproof the tank. Alternatively could I still use it to shape glue dividers in place (I still have my heart set on a glass stone wall), and use a large plastic box for the water? (Will need to hunt for one)

For the lids, did you guys make them yourselves? Not too sure where I can get alternative lids for my tank. I think I would need to invest in a glass (part glass part wire for lights? Do I need lights?) one, live in California where it’s super dry. I know my local reptile shop uses in tank humidifiers for their chameleons, would that work instead? (Still need a good hydrometer)

Thanks so much for feedback!

Yes! A contained water pool is definitely safe as it will be watertight. A lot of people who use them recessed into the sub will double them up so the top one can be removed for cleaning without any cave ins.

You should be able to get away with wrapping the lid in plastic wrap to hold in humidity if you don't want to do anything fancy. Alternatively you could cut glass or plastic to fit into the top over the screens. I think they may even sell Exoterra brand inserts for them.