HCA: Hermit Crab Association

Has anyone ever had algae in their substrate? My tank is a 30gal and I have always had a small problem with the maintaining the humidity. I do end up spraying my tank about one time a week and I try to stick to the moss pit and the grapevine log I have my tank covered with a glass lid, a insulated and covered with a towel as we like our house a little cooler like 67 degrees Fahrenheit. Since this tank is at the end of the hallway it doesn’t get much light so I have a regular lamp with a 12 on and 12 off cycle. Today I noticed that it looked green about 1.5 inches under top of the substrate. So I was just wondering what should I do? I SHOULD have 4 crabs in there and I know at least one of them is up and active. I have my bigger tank that SHOULD have 5 crabs in that I could move these crabs into. I know at least 3 in the bigger tank are under molting.in the bigger tank I have better humidity and bubblers and more climbing things. My intentions were to always join the two groups of crabs. I just was wondering what and how to deal with the algae if it is algae.


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Can anyone give me any advice before I go and take everything out of my tank?
And start digging crabs up? I really don’t want to, but if it’s necessary, I will.

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Could you post a photo of the algae? Like is it on the top and 1.5 inches through the whole sub? Or do you see it just along the walls of the tank, 1.5 inches down?

curlysister wrote:Could you post a photo of the algae? Like is it on the top and 1.5 inches through the whole sub? Or do you see it just along the walls of the tank, 1.5 inches down?

I only see it in the front. And one of my crabs ( I THINK it’s Marina) is almost right underneath it you can see in the picture, her window to the outside world. Usually the lamp is laying down on the tank with the bulb sticking over the edge, but to take the picture I was holding it in one hand and taking the picture with the other.


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CrabbyChelle628 wrote:
I only see it in the front. And one of my crabs ( I THINK it’s Marina) is almost right underneath it you can see in the picture, her window to the outside world. Usually the lamp is laying down on the tank with the bulb sticking over the edge, but to take the picture I was holding it in one hand and taking the picture with the other.


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Annnnd I just noticed that they tipped their thermometer/hydrometer over.


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Yeah, that looks like algae. I have never had algae, but you don't have to tear things down like with a bacterial bloom from what I understand. Don't panic.

curlysister wrote:Yeah, that looks like algae. I have never had algae, but you don't have to tear things down like with a bacterial bloom from what I understand. Don't panic.

Ok what do I have to do?


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CrabbyChelle628 wrote: Ok what do I have to do?


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Or I should be asking do you know what I need to do?


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You don't have to do anything. It won't harm your crabs at all.

I have had algae on my damp end where the moss pits are and fewer UTHs for years. It hasn’t really spread and doesn’t seem to be a problem.


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Algae is the combination of 3 things, light, moisture and nutrients. They will grow, and its relatively normal. Algae by itself is not an issue, however, it could indicate that the substrate is getting a little too moist, so you may want to check for a flood.

To check, you get a chopstick, ruler, butterknife (anything long and flatish) and make a little hole down the front glass, when you lift out the object, if water fills the tunnel it indicates a flood. If the sand collapses, the substrate is dry and if it maintains it shape with no standing water, the substrate is perfect.

aussieJJDude wrote:Algae is the combination of 3 things, light, moisture and nutrients. They will grow, and its relatively normal. Algae by itself is not an issue, however, it could indicate that the substrate is getting a little too moist, so you may want to check for a flood.

To check, you get a chopstick, ruler, butterknife (anything long and flatish) and make a little hole down the front glass, when you lift out the object, if water fills the tunnel it indicates a flood. If the sand collapses, the substrate is dry and if it maintains it shape with no standing water, the substrate is perfect.

Ok thanks


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