What Is This?

[Noahsfish]

I'm guessing this is some sort of mineral build up?  But I never splash water, and this isn't on any of my other tanks.
 

 

[sputnick]

My tank has the same thing. I think its a type of mold maybe? Because the air around the hole is so much more moist? I'm truly not sure. I hope someone else has a good answer cuz i want to know too!

 

[TallTree01]

I've definitely seen it before. I can't remember where. It never hurt anyone though.

 

[dougie]

I was going to suggest lime scale, but as it's not on your other tanks I'm not so sure. Is there something different about this tank compared to others? Is the hood a different material?
Does it wipe of easy or is it quite stubborn?

Dougie.

 

[Noahsfish]

Well, I have one other tank that has a identical hood, the only thing different is the heater is much further down. (the purpose of the hole)

 

[rpgmomma8404]

Think it is calcium build up from the water. I had that on all my tanks that I had when I was a kid. It doesn't bother the fish as far as I can remember. 

 

[the_lock_man]

My intial thought is limescale as well. Do you live in a hard-water area?

 

[dgwebster]

Its mineral deposits from your evaporated water coming out of the hole there. Its more excessive due to the proximity of your heater. Either cover the hole (clingfilm?) or move the heater further away.

Edit: evaporated is the wrong word, but it is from this process.

 

[Lunar Jetman]

I'd agree with the above that this is a limescale/calcium build up. I get it on my fluorescent tubes sometimes where moisture builds up on them and evaporates. Looks like a splash pattern to me based on the fact it's around the hole. It could be minute splashes that build up over time rather than where you've splashed.

 

[Noahsfish]

Yeah, I was guessing it had something to do with the heater being close to the surface. Thanks

 

[Sophie]

Washing machines live longer with calgon!

 

[frapadoodle]

Washing machines live longer with calgon!

Wow! Have not heard that since I was a boy.