Is the tank water volume include the sunp volume ?

[Alexoss]

Simple question but didn't find any simple answer yet, for example, when we talk of 10% water change a week, is it 10% of the DT water volume only, or does it include the sump water volume too to calculate the 10% to change ?
I m about to start two tanks (37 g with sump, and 170 g with sump), so to plan my water changes that may be usefull to know now, thank you all.
edit : juste noticed the "sunp", sorry about that.

 

[WIReefer]

I consider the sump water volume when doing a water change. I change 10% of the entire systems water volume.

 

[Saltyreef]

Total water volume.
You have to remember, sand, rock and equipment displaces a lot of water too.

I like to fill up my tanks for the first time with some sort of mesuring device so im accurate on volume

 

[Alexoss]

Ok that make sense, that would have been my first idea, but better ask to start well in reefing.

 

[vetteguy53081]

Two separate volumes.
With my main tank and sump together, there would be 800 gallons. I consider it a 660g

 

[Azedenkae]

Simple question but didn't find any simple answer yet, for example, when we talk of 10% water change a week, is it 10% of the DT water volume only, or does it include the sump water volume too to calculate the 10% to change ?
I m about to start two tanks (37 g with sump, and 170 g with sump), so to plan my water changes that may be usefull to know now, thank you all.
edit : juste noticed the "sunp", sorry about that.

10% of total (display and sump).

Technically that is not the total water volume, because of sand, rocks, equipment, etc., but that's fine. You woulf basically just be doing a higher % water change than intended, no biggie.

 

[ying yang]

You have display tank volume.
Sump volume.
Add together = total system volume .
And to do 10% water change would be of total system volume.
As said rocks and sand displace water.
Every system different with amount of sand/ no sand,lots of rocks or few rocks and even the kind of rocks as some rocks more dense or more pourous so hold more water inside the rocks etc but i would guess the displacement of water from my rocks and sand like 15- 20% so i minus 20% of volume of tank when working out my total water volume ( which at best is just educated guess,unless measured water as filled system up.)

 

[Azedenkae]

You have display tank volume.
Sump volume.
Add together = total system volume .
And to do 10% water change would be of total system volume.
As said rocks and sand displace water.
Every system different with amount of sand/ no sand,lots of rocks or few rocks and even the kind of rocks as some rocks more dense or more pourous so hold more water inside the rocks etc but i would guess the displacement of water from my rocks and sand like 15- 20% so i minus 20% of volume of tank when working out my total water volume ( which at best is just educated guess,unless measured water as filled system up.)

Yeah unless one measured when filling up, it would be pretty hard to know how much water there is. For me true water volume was actually only 70% of total volume, but I also have a pretty small tank (20 gallons) so equipment and stuff may have taken up more volume. I think larger tanks would be more akin to what ying yang suggest, like 20% of the total volume taken up by things other than water.

 

[Alexoss]

To be sure i ll consider the total volume DT + sump for WC, better safe than sorry, and i trully believe water changes are the backbone of any healthy tank.