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Setting Up Pools - A Complete Guide

Pools in a Hermit Crab Tank are extremely important, just as important as having the correct substrate. Not setting up your pools correctly can have dire consequences on your crab's health and tank conditions.

When setup right, it will aid in your humidity levels and your Hermit Crabs overall health. As daunting as it may sound, they are very easy to setup, and you can even set up oxygenated pools with bubblers or filters.

So why are pools so important? Hermit Crabs need both salt water and freshwater pools in their tank; salt water to bathe, drink, fill shell water and spawn zoea, and freshwater to bathe, drink and fill their shell water. Hermit Crabs will often move between both pools and fill their shells with the required salt water and fresh water to combine them in their shell to create their preferred salinity. This is why it is so important to have pools deep enough for your largest crab to fully submerge their entire shell, by submerging their shell, they can fill it with water. Hermit Crabs will fill their shells with water to keep their delicate abdomen moist, as well storing water for moulting.

Pools can be made from anything from take away containers, plastic Tupperware or small glass Aquariums and bowls. Both Pools need an easy way in and out, this prevents drowning. Possible access points include fish egg crate, wood, plants, stones, gutter guard etc. Both Pools should be treated using Seachem Prime water conditioner. The salt pool should also contain a high-quality, marine grade salt from an Aquarium.

Pools can sit above the sub, in the sub or on a second level or stand.

Still water pools should be replaced every 48 hours.

Setting Up Aerated Pools

Why set up aerated pools? By adding oxygen into your pools, it will help aid in the humidity within your tank, requires less water changes and keeps your pools cleaner for longer.

There are 2 ways to aerate your pools; with bubblers or filters. Both are easy to setup, and easy to maintain.


Bubblers are made using air stones, airline and an air pump, air is pumped through the airline, into the stones and creates a bubble effect in the water.

Pools with bubblers will require the water to be changed every 7 days.

Equipment Required -

  • Air Stones x2

  • Aquarium Air Line

  • Aquarium Air Pump (single outlet or double outlet)

  • Check Valve (x2 for double outlet)

  • T Line Splitter (only needed for single outlet)

Setting Up Bubblers

  • Connect your air stones to the end of the air line, depending on if you have a single outlet air pump or a double outlet, you will need to cut the air line and place a line splitter.

  • Line splitters have 3 parts, 1 side connects to one air stone, the other side connects to the other air stone and the middle part connects to the air pump. This step is only needed if you have a single outlet pump.

  • Connect the check valve between the splitter and the pump like pictured below. Check valves prevent water entering back up into the pump if it fails.

  • With the final part of the airline, connect it to the air pump outlet. Place the air stones into the pools, plug the pump in and turn it on. You should see bubbles rising to the surface within seconds.

  • If you have a double outlet pump, simply connect your tubing to the air stones, add both check valves (one for each line) and connect the rest of the tubing into the pump.

  • Air stones must be fully submerged under the water for them to work correctly.

Pictured below is the required equipment to set up bubblers. These can be found at Aquariums or most pet stores.

* Air Stones - small sizes 1-3 inch are best for Hermit Crabs pools.

* Air Line Tubing - Its best to grab a few meters of this to prevent running short. 4mm is the most standard and common size.

* T Shaped Line Splitters - Only needed if you are using a single outlet pump.

* Check Valve and how to install it. The out part should be connected to the tube that goes into the air stones.

* Single Outlet Air Pump

* Double Outlet Air Pump

* Setting Up A T Shaped Line Splitter

Trouble Shooting Bubblers

Setup your bubblers correctly and still no bubbles? Check out these trouble shooting tips below.

  • It could be 3 things causing the issue, the air stone, the air pump or the line tubing. The quickest way to figure this out is by removing the air stone and placing the tubing back into the water, if there are a lot of bubbles coming out, the issue is in your air stone, if there are no bubbles, the issue is in your tubing or pump.

  • If the issue is in your air stone, replace it. Air stones will build up muck and calcium residue overtime, which will block them up. It is recommended to replace your air stone every 6 months; they are very cheap and easy to replace.

  • Some air stones are also denser than others, and perhaps your pump is not strong enough to get the air through. We recommend purchasing an air pump that is between 2500 to 2700 (and no, that is not the price of them) 2700 air pumps work better for deeper and larger pools and come with a double outlet.

  • If the issue is in your pump or tubing, check that there are no holes or kinks in the tubing, if there are, either fix the kinks or replace the airline, these are also relatively cheap to replace.

  • If it appears to be your pump, the issue may be that it is not strong enough to get the air to the bubblers, by placing the pump above your pool level (on top of the tank or a shelf beside it) there is less effort on the pumps part to get the air down into the stone. If your pump has a control system on it (high and low) try turning it onto the high setting.

  • Air pumps will only last a few years, so if yours is quite old and starting to struggle, replace it.


There are two kinds of filters you can add into your pools, Sponge Filters or Internal Filters. Sponge filters connect to your air pump just like an air stone would, whereas internal filters plug straight into the wall and are placed directly into the pools, no need for the air pump.

Unlike bubblers, that only aerate the water, filters will aerate and clean the water, making it last longer.

Sponge filters are relatively cheap and very easy to setup. Instead of connecting your tubing to the air stone, connect it to the top of the sponge filter. These must be completely covered in water in the pools for them to work. The sponge should be replaced completely every 6 months, the great thing about them is that you can remove them, give them a good wash in hot water and place them back into the pools.

Internal filters work just as well; however, they can be on the more expensive side and are more suited to larger pools.

Pools with filters require the water to be changed every 3-6 months, making them the ultimate aeration system for busy owners.

* Sponge Filters (if you find the plastic tube is too tall for your pool, simply remove it, you don't need it and it will not affect the filter's function)

* Internal Filters

* Pools pictured belong to The Happy Hermie, 1 x 10L Salt Pool, 1 x 10L Fresh Pool

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