Makin' it rain

[pseudorand]

I awoke this morning to my ATO beeping about the water level being about 2" higher than it should be. My sump is a 24x12 20gal, so that's about 2gal of water. I can't figure out where the extra water came from.

Facts:
1. It was NOT beeping around 2 am last night when I went to bed. (It's now 8:30 am)
2. There is no visible water on the floor. The aquarium is in the basement and all water would flow to a drain over concrete, but it takes a while and I always see standing water when I spill or dump buckets. I have had equipment leak and I've always had noticeable standing water.
3. All pumps are still operational.
4. The tank level is the same (it's got a HOB overflow).
5. The ATO is full because I left the RO/DI running overnight to refill it.
6. The skimmate locker is close to empty. I just drained it last night, but closed the valve. It only holds about 1/2 gallon and probably only has about 1/4 cup in it at present.
7. Salinity is maybe down a bit (0.0001). I keep it at 1.025. It's now between 1.025 and 1.024 via refractomerer. The tank is a 120g, so that's about consistent with 2g water loss from some unknown event + whatever my skimmer has drained (and ATO replaced) since my last water change about 2 weeks ago.

My current working hypothesis is that leprechauns have made it rain in my tank. I know it seems far fetched, but that's the best I've got at the moment. Anyone have a better idea?

 

[Super Fly]

do u have pix of ATO tube that goes into sump?... THink there may have been a siphon with the ATO tube while filling which resulted in the extra 2 gallons in the sump. The RODI left on over night to fill the ATO reservoir explains full ATO.

 

[pseudorand]

For syphoning, the ato hose would have to be submerged, no? It's at the top of the sump. The sump would have to be almost overflowing to submerge it. The other end is in the pump at the bottom of the ATO reservoir, so the outlet is higher than the inlet.

 

[Auquanut]

Lets get back to the most plausible possibility: Leprechauns. Is it possible that you had a blockage at the weir that caused the level in the tank to rise slightly, and these industrious leprechauns (or fish, or urchin, or water pressure) cleared the blockage? That would explain the rise in the sump.

Unfortunately, my leprechauns mostly just hide my car keys.

 

[pseudorand]

Lets get back to the most plausible possibility: Leprechauns. Is it possible that you had a blockage at the weir that caused the level in the tank to rise slightly, and these industrious leprechauns (or fish, or urchin, or water pressure) cleared the blockage? That would explain the rise in the sump.

Unfortunately, my leprechauns mostly just hide my car keys.

I did stick my arm in the tank to reposition a coral, but that was hours before I went to bed. The water level was inches above the alert line. If I didn't hear it last night, it must have happened much later than that.