Bottom of substrate getting wetter?

[kfinnz]

I'm not sure if I just didn't notice it before (pretty sure that's not the case) but today I was looking in my tank and it seems the bottom half of my substrate is getting darker like its getting wetter? I was concerned about maybe a pool leak but both are fine and the sand directly under them isn't unusual. Could high humidity cause bottom sand to become moister? Does substrate just darken over time?

[Happyhermiehome]

If u dig down with your finger to where it's darker does it smell bad?

[kfinnz]

Not that I can tell. Same crab tank smell I usually smell, kinda like....I always say like a wet penny or a wet rock after rain if that makes sense?

[GotButterflies]

Do you spray your tank? Do you have bubblers that might be causing overspray?

Take a chopstick or a pencil down the front part of your tank to see if it is indeed more wet.

[wodesorel]

Do you have crabs down right now? If the answer is no, then a substrate mix up is never the wrong choice! It will aerate it, and also let you see what is happening.

Water does sink to the very bottom and can build up over time from high humidity levels. Bacterial blooms can cause sand to darken. If you have used cocofiber it can stain the sand over time if wet enough. And yes, it does seem to darken as it absorbs more moisture over time. However, because flooding and blooms are extremely dangerous it is best to do a little digging so long as you aren't disturbing molters and make sure nothing bad is happening at the very bottom!

[kfinnz]

I do have at least one crab down rn I think. One I know isn't molting he's just digging around because I still see him often, but ones been down for months. I'm gonna try the pencil in an area I saw him move away from recently and see if that shows me anything. Are bacterial blooms like mold?

[Happyhermiehome]

I do have at least one crab down rn I think. One I know isn't molting he's just digging around because I still see him often, but ones been down for months. I'm gonna try the pencil in an area I saw him move away from recently and see if that shows me anything. Are bacterial blooms like mold?

It's an over growth of bacteria that flourishes in the presents of low oxygen and standing water. It will turn the sand grayish black and it stinks really bad! Like rotten eggs meets sour milk bad lol. I had one last year in my 20g when a water dish was leaking unchecked and I was over misting. When I started emptying the tank it made my whole house stank! I had to take everything out side! Fortunately I had no molters down at the time.

[kfinnz]

So I did the pencil thing and at the VERY bottom it's deffinitely wetter, not so much that the sand doesn't hold shape though. Sand still just same slightly darker color. Although it doesn't smell repugnant or anything, so would it not be a bacterial bloom? I'm guessing it's best to wait till the two crabs under rn come back up and reevaluate and remix the substrate if needed?

[wodesorel]

Limit water going into the substrate and make sure the lid is nicely sealed so that the dryer top of the substrate draws excess moisture up. If you are lucky it will correct itself in a few weeks with no harm done. Keep checking to make sure it doesn't start smelling - that constitutes an emergency. Bacterial blooms start somewhere in the center bottom away from light, and produce deadly methane gas and also acid. Molters in the area often die not from standing water but from the bloom itself. Sand also will be very dark, greyish and sometimes actually black, and these patches can be spotted from underneath if you have the tank on a fish tank stand.

[kfinnz]

It's not on a fish stand unfortunately, the tank sits on top of my large dresser. If it is a bacterial bloom but I cannot tell for sure yet will it hurt my surface crabs at all?

[wodesorel]

It could eventually affect surface crabs from the gas that develops, but it would have to be a serious bloom to pump out that much. You should be able to smell it before it ever gets to that point! Most people do not realize there is anything amiss until their crabs don't come back up from molting, everything on the surface carries on as normal.