Dry rock - absorbing water?

[Theulli]

So I put about 60 pounds of dry rock in my new tank yesterday - obviously it displaced a whole bunch of water, but I came down this morning to find that the water level in the tank had decreased significantly more than I would've expected with evaporation. Not alarmingly, but significantly. Inspected everything for leaks and I can find nothing. My working theory is that the rocks, while initially displacing water, will absorb some of it back, because they're porous - is that reasonable?

Otherwise I'm back to looking for leaks

Thanks!

 

[T-J]

It can only absorb what it displaced. Like if I put a sealed can into the tank, it will displace the outside volume of the can. If I open the can underwater, the displaced water will not take the place inside the can.

Have you checked your tank temperature? How much lower is your water? Did your salinity change drastically?

 

[Theulli]

Salinity was almost exactly the same so it wasn’t evaporation. I think it was the rocks, plus I am still tuning the system and for reasons I am not sure of it seems to reach an equilibrium when extra water is in the sump rather than the overflow. Tested adding a bunch of water this morning and that’s what it looked like

 

[NowGlazeIT]

Wow that sounds like some good rock, when I got my jumbo pukani back in the day, it weighed 30 lbs dry. Now it weighs 70lbs wet! They can suck up a lot of water.

 

[terraincognita]

Wow that sounds like some good rock, when I got my jumbo pukani back in the day, it weighed 30 lbs dry. Now it weighs 70lbs wet! They can suck up a lot of water.

Looks like they can lol.

Based on that depending on how long it took them to absorb water vs displacement it would be 5 Gallons worth in his case. Yours could be more again depending on the rock.

I always thought it was much quicker though, like within a couple minutes, not neccesarily an overnight thing. Guess it depends on the Rock and how much.

 

[NowGlazeIT]

Looks like they can lol.

Based on that depending on how long it took them to absorb water vs displacement it would be 5 Gallons worth in his case. Yours could be more again depending on the rock.

I always thought it was much quicker though, like within a couple minutes, not neccesarily an overnight thing. Guess it depends on the Rock and how much.

Yea I think it would take awhile on bigger rocks. And the whole displacement is more viable if the rock was added after the water, so I hear you there. Why are we adding rocks after the water is my question?

 

[Goaway]

I am feeling extra dumb this afternoon.

25lbs of dry rock from marco rocks turned into double that over the year.

If you have tests recorded, I would test water now and compare notes. But, you probably already topped off water.
Test would be nice to see if you need to look for leaks, evaporation or just rock doing its job. It's also not difficult to find a leak if you lost over a gallon. Depending on tank size and circulation, you can lose half a gallon to a few gallons over 24 hours.

looks like you have a 100g with a 29g sump? That can be 1 to 2 gallon loss easy.

 

[terraincognita]

I am feeling extra dumb this afternoon.

25lbs of dry rock from marco rocks turned into double that over the year.

If you have tests recorded, I would test water now and compare notes. But, you probably already topped off water.
Test would be nice to see if you need to look for leaks, evaporation or just rock doing its job. It's also not difficult to find a leak if you lost over a gallon. Depending on tank size and circulation, you can lose half a gallon to a few gallons over 24 hours.

looks like you have a 100g with a 29g sump? That can be 1 to 2 gallon loss easy.

oh yeah on a 100G you can have like 2-3 gallons in your pipes while it's running .

Lots of room for "missing water" on a 100G system with a 30G Sump.

 

[Theulli]

Yea I think it would take awhile on bigger rocks. And the whole displacement is more viable if the rock was added after the water, so I hear you there. Why are we adding rocks after the water is my question?

I used live sand and I didn't want to dry it out, so I did water first, sand second, rocks third.

 

[NowGlazeIT]

I used live sand and I didn't want to dry it out, so I did water first, sand second, rocks third.

Ohh yup that makes sense

 

[ColoredRock]

I used live sand and I didn't want to dry it out, so I did water first, sand second, rocks third.

Im in the process of setting up a tank... been out of the game for awhile and read that you want to place rock first on the bottom and then sand.. Reason stated was the concern for the rock to shift over the sand over time. and possibly create your aquascaping to fall down.