HCA: Hermit Crab Association

Hi! I’m currently in the process of getting a list together of what I will need for my new tank. My hermits will be moving from a 10 gallon to a 40 gallon in the near future. I’m currently looking at pool ideas. I was originally planning to use a small air pump, and putting air stones in the pools. Would a water filter be better? Does with one keep the water fresher? What would work best? Thanks for answering my questions!

A filter would provide a medium for denitrifying bacteria, which would help detoxify nitrogenous waste once properly cycled. Cycling can take anywhere from a few weeks to a few months with a steady supply if ammonia.

If you can find a small enough sponge filter you can have both a filter and bubbler in one.


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Oh alright. You can probably tell I’ve never had fish... I’m sorta new to the website (Haven’t posted much/or met anyone) but is there a discord or something like that for questions? I would honestly love to talk about this with someone. Thanks for the reply! -Becca

You can cut down a sponge fairly easily, but I worry that the crabs would eat the sponge.

mool wrote: ↑

Sat Mar 13, 2021 11:23 am

You can cut down a sponge fairly easily, but I worry that the crabs would eat the sponge.

I wouldn't worry too much about that, but if you're worried, a box filter (a sponge filter with extra steps , also called a corner box filter, or air driven box filter) could work nicely.

Becca24 wrote: ↑

Fri Mar 12, 2021 8:52 pm

Oh alright. You can probably tell I’ve never had fish... I’m sorta new to the website (Haven’t posted much/or met anyone) but is there a discord or something like that for questions? I would honestly love to talk about this with someone. Thanks for the reply! -Becca

Yep! https://discord.gg/jbYtPaXN

Becca24 wrote: ↑

Fri Mar 12, 2021 8:52 pm

Oh alright. You can probably tell I’ve never had fish... I’m sorta new to the website (Haven’t posted much/or met anyone) but is there a discord or something like that for questions? I would honestly love to talk about this with someone. Thanks for the reply! -Becca

If you've never had fish, I'd say it would depend on the size of your pools. Since you're new and their new tank will be a 40 gallon, I'd say stick to a pump and air filter for right now for bubbles. I'm planning a 75G and this is my plan to start, even though I've had fish before.

The reason being, it's REALLY hard to keep small bodies of water good even with an API test kit. Even though they're crabs and they're not in either pool 24/7, they'll be in it enough over time to where it might be hard for your filter to do justice. The smaller the body of water, the faster EVERYTHING backs up - ammonia, nitRITES and nitRATES plus factor in any sand/EE drug into the pool that might get stirred up enough to enter the filter. Plus any food particles and moss bits, etc.

Sponge filters fit to the outside of the unit and yes, crabbies do sometimes munch on them and if not that - like certain boisterous fish, can yank them off, etc (from what I've read). Plus filters take up room inside the tank pool itself. When you add that in with an airstone/bubbler if you want, some substrate like gravel or river rocks, etc. for the bottom and a ramp of some kind - it might be tight, size wise, in the pool.

Knowing fish, and researching crabbies, the only main benefit from filters in pools is so you don't have to necessarily change out 100% of the water in the pools every 1 - 3 days. However, having a filter means you still DO need to change water frequently - for such a small amount 75% at least and replace with fresh. It's so tricky, you CAN do it but would it really help/save you anything? That's hard to say.

If you have 2 - 5+ gallon pools then yes, filters would be great. But a gallon each or less, might be better just changing it 100% and keeping the airstone/bubbler. I'm still learning so this is just my opinion, I don't mean to discourage. I just know how hard it can be with small bodies of water and filtering is all while keeping good API numbers. The bigger the pool, the better for cycling/filtering in my opinion.

Listen more to the pros here who have done this for a long time!