how many actual gallons

[robert teseo]

is there any formula for pounds of rock displaces how many gallons? I have a 75 with over 100 lbs of rock, so how many gallons of water do I have? I,m sizing a chiller. I know there's not close to 75 in there

 

[hijinks7]

There is no formula since different types of rock is more porous then other types. Even figi rock some is more porous then others. The only thing to do is fill up a bucket and put the rock in and see how much water it displaces then add it all up

 

[Daniel@R2R Verified Admin]

Seems like I saw a formula somewhere based on the number of pounds of rock involved. I agree with @hijinks7 that any such formula is going to be a rough estimate at best due to different rock densities and such. If you're looking for precision, measuring the displacement is about all you can do. I've never sought to be that precise...

 

[robert teseo]

i don't want to get that crazy, and I,m not going to disturb the tank so. to cover my behind, I,m buying the next size up chiller. it will be overkill, but mean no worries next summer

 

[hijinks7]

If you have a 75g and 20g sump buy a chiller rated to 100g. Bigger is always better if you can afford it to the point its not cycling on and off too often.

 

[robert teseo]

actually, I,m buying a heater/chiller rated up to 230 gallons. the fish room can get to the upper 80's in the summer