Hole method or not?

[kuza]

if your room is 80f then you're fine without one.

[Mikau132]

Thanks! My little sister wants two crabs also (I would of course help her take care of them and maybe help her financially.) and I told her everything you guys have said and am making a care/cleaning schedule. She is really excited and is doing tons of work around the house for money. She has found several shells on the beach that we have been boiling for about 5-10 minutes each. She is 9 and has a small fish tank. Do you think she is ready for crabs? I told her I'd help her set up the tank and ISO.

[dylan644]

As long as someone is keeping a close eye on her and the crabs, I'm sure they will be fine.

[dylan644]

Also, your going to need four dishes. One for food, one for freshwater, one for saltwater and one for calcium. You need to have some type of calcium supplement for them. They use calcium in there exsoskeleton. It helps keep it hard. Since they molt, some of that is lost so they need a way to compensate to get back needed calcium. Cuttlebone, crushed coral/shells and eggshells are great calcium sources to give. Keep the dish dry and change it out every other week.

[Mikau132]

Thanks for all the help guys. I'm going to get them in two or three weeks so I can set the tank up right and get all the supplies and get the temperature and humidity to balance out.

[JediMasterThrash]

The corner-hole method solves a very specific problem.The problem is how to get moisture uniformly throughout the substrate, and the answer is not misting or spraying.Water will quickly evaporate off the top layer of substrate, especially sand, and especially if there are overhead lights. Any misting will provide a quick, temporary humidity boost, but will do nothing to improve the moisture level of the substrate itself. The key to keeping good humidity in a tank is a base of mid-level to lower-level sand-castle-moist substrate.Fingering holes into the corners is safe because you can easily see into the substrate around the corners to make sure there are no crabs.If you stick to the recommended amounts (1/4-1/2 cup per hole, depending on the side of your tank and depth of substrate), there is no risk for flooding.This is the only way to get the water directly into the lower levels of the substrate. From that point on, within about 30 minutes the water will have wicked throughout most of the substrate, creating a more uniformly moist lower substrate, and there will not be any pooling or concentration of water level.The substrate will then be able to retain this moisture for a long time, up to a few weeks, so you do not need to mist every hour to keep the substrate wet, you can just do the corner-hole method once or twice a month, depending on how quickly the substrate dries out.Making sure the substrate is sand-castle moist when the crabitat is first created is still only a temporary solution. Within a month the entire substrate can still dry out, leaving you still with the ongoing maintenance of how to keep the substrate at proper moisture level.Molting crabs will break the surface dryness by dumping shell water and then digging a hole. The moist sand in the mid to lower levels supports their molting caves and provides them the humidity they need during molting.

[kuza]

Can we enter the theory zone for a minute?This is just my opinion from trial and error over the past couple of years, but I don't agree that the tank will ever dry out bottom up. If your substrate is drying out at the bottom then I believe you have issues with your setup. This should not happen, it "should" dry out top too bottom. A proper setup will naturally send moisture to the lower levels because of the earths natural vibration and gravity. The top layers will dry out faster then the bottom 99% of the time because of air flow and lights. So I believe the corner hole method is for extreme situations where the whole substrate has dried out. For the top layer drying out you should use the water throw method, Wodresel made a great video of it that I can't seem to find at the moment. This is why I suggest people keep 1 inch at the bottom fairly dry at the start, it'll get wet on it's own, naturally. If it starts out wet, it'll just get more wet as time goes on and the water shifts to the bottom. It'll almost never dry out at the bottom before the top layer. The only time I've even heard about the bottom drying out first is when peat moss is used instead of cocofiber. But JMT is right, you need to properly moisten the substrate before it goes in the tank.

[Crabber85]

@Kuza, water does in fact migrate to the bottom of the enclosure over time and this process can lead to the bottom layer of the sub becoming soupy especially if you tend to mist a lot, use a diy humidifier or bubbler as what goes up must come down and will eventually work it's way to the bottom.I've never had the bottom layer of sub get soupy or overly wet because I rarely mist and I don't do bubblers or diy humidifier anymore as they just aren't needed in my case.

[Keg]

I use aquarium gravel in the area where I add water. It slows down the erosion from adding water. If I had thought it out better, I would have put the gravel at the shallow end of the sand. That way it would encourage the crab to molt near the deeper sand, and I could add water during Azazul's molting period if I needed to.In Arizona, mine dries from the top down. If I didn't add water now and then, I think it would be completely dry in a year.

[JediMasterThrash]

The substrate does dry out from the top down, and that is why adding water only to the top can result in the water evaporating before it reaches the bottom, and the bottom will have difficulty rebuilding its moisture.Over time the bottom will still lose moisture as long as the substrate above it is dry, and the air/lights will keep the substrate at the top dry. If you have UTH, even mounted on the sides, those will dry out lower substrate quickly as well.The bottom definitely will dry out, even with high humidity. I started with full sandcastle sand, and within one month it was dry without adding any water. It was probably drying out about twice as fast as usually due to it being winter so the overall house %RH was low, but still it does happen. It takes about 2 months in the summer with higher house RH to dry out 6 inches of sand.I used to put a layer of larger smooth aquarium gravel in the bottom of the tank to act as a drainage layer. It did help, but it didn't last. Within 6 months of crabs digging tunnels and burying, the gravel was pretty much uniformly mixed up with the substrate, showing up all over the surface as well.If a sufficient amount of water is applied to the surface, then it can seep into the lower substrate before it all dries out. I usually find dumping about 3 whole cups of water (into a 92g tank) is the minimum required to ensure it replenishes some substrate moisture before the top dries out. But plain misting will just evaporate before making any headway towards increasing substrate moisture.