Leaking/overflowing? Not sure.

[Sheehantastic]

And the stand floor is completely dry when there is water on the floor…. Maybe put tinfoil or Mylar paper around the sump and see if it collects any water. If you had access to underneath, you can put tinfoil with a slight v bend in every sheet under the tank, that way you would see exactly where the leak was coming from as the water would just pool on the sheet under the spot.
A couple gallons of water is quite a bit, enough to cover most floors and damage baseboards. Are you sure it’s that much? A couple gallons of water is four 2L pop bottles.

Off topic, but if your tank is 140g ish, you may want to run a larger sump. For example, my 65g has a 15g sump. A 40g breeder would likely fit nicely and give you tons of room to have lots of mechanical and a fuge.

I'll try the foil idea and see what pans out. I'm going by how much my mop bucket it filling up, which I believe is a 5 gallon capacity and filled about a third of the way last time I mopped everything up. The part of my basement that has my DT has painted concrete walls so no worries about baseboards.

When I built the stand I didn't think about sumps (I know silly of me) so the biggest I can fit between the braces is 20 gallon. I do have a second 20 gallon that I'll be putting on the other side, I just haven't set it up yet.

 

[Dburr1014]

I'm using a 3 piece acrylic lid.

Possible the evaporation on the lid gets to be to much and leaks to the floor?

 

[Sheehantastic]

Possible the evaporation on the lid gets to be to much and leaks to the floor?

I thought of that, but no. The last time it happened I had left my lids off after some algae scraping.

 

[Ziggy17]

I hope you get some answers soon. Can’t be enjoyable mopping and not knowing where it’s coming from.

 

[Reefer Reboot]

Long shot but worth a try, might you have an anti siphon device on the ato line that could be dribbling water onto the floor?

 

[Sheehantastic]

Long shot but worth a try, might you have an anti siphon device on the ato line that could be dribbling water onto the floor?

I think I actually just figured it out. My filter socks are getting backed up and overflowing out of the sump. It's happening slowly and intermittently enough that I only happend to notice it because I was in my office for several hours straight. But it seems to be the culprit. It's been several weeks since it last happened, but started to again today. So I think that might be it. I repositioned them a couple hours ago and no new water on the floor. Fingers crossed.