Tank leaking(?)

I was not at home today. When I came back, the water level in my tank reduced by 15 centimeters ( which is very unusual). A while later, i spot a puddle on the ground.
The tank is on top of a desk but all the paper on the table isn't wet at all.
I have 2 suspects.
First is the tank leaking. I've noticed a small cracks that wasn't there before. On the lower left corner , some of the glass is broken broken. It feels like someone has broke the surface with something like a chisel
Second is HOB filter overflowing. The cover is very wet. The HOB is on the back so the water might have not spread on the table.
Should I fill up the tank again or disassemble it ? I had never have a problem before with this tank

That corner looks very worrying! But if there is no water there it sounds like it could be your HOB? I don't know much about HOBs though so cant be certain but I have heard of them over flowing?

Wills

Is the HOB clogged at all? Whens the last time you cleaned it?

If the table is dry then water might have drained down airlines or power cords on filters heaters and lights. You need to check all them and make sure the filter is angled slightly into the tank so it can't overflow out the back.

Make sure there's no material or paper near the top of the tank because it can wick water out of a tank and onto areas nowhere near the tank.

--------------
After checking the above, I would fill the tank and monitor it over the next few hours. Mark the water level with a felt pen (permanent marker) and see if it drops.

connorlindeman said:

Is the HOB clogged at all? Whens the last time you cleaned it?

Click to expand...

No. But sometimes it overflow for a little bit and it'll get back to normal in a minute. I changed the filter mat last month.

Colin_T said:

If the table is dry then water might have drained down airlines or power cords on filters heaters and lights. You need to check all them and make sure the filter is angled slightly into the tank so it can't overflow out the back.

Make sure there's no material or paper near the top of the tank because it can wick water out of a tank and onto areas nowhere near the tank.

--------------
After checking the above, I would fill the tank and monitor it over the next few hours. Mark the water level with a felt pen (permanent marker) and see if it drops.

Click to expand...

Thanks for the tip! Will definitely do this.