Total Water Volume?

[NanaReefer]

This subject isn't talked about much. But I think it is important especially when it comes to dosing.

I tried really hard to measure my total water volume when setting up my new 40B/20L sump. After adding 80# of live sand to tank/sump and 25# of cured (water logged) reef saver rock, I was only able to add 42-45 gallons of water to my tank. Does this sound about right?
When and if I ever need to dose anything should I not go by total actual water volume and NOT the size of the 2 tanks?

 

[mfinn]

Yeah it is hard to get it right unless you measure it when you fill it the first time.
I usually guess as to the actual water volume. I imagine the rock and sand being flat across the bottom and guess the percentage, then add in the actual volume of water in the sump.
With some tanks that are really packed with rock and sand, you might over dose if you went by the total volume of both containers.

 

[Holygral]

http://reef.diesyst.com/volcalc/volcalc.html

Volume calculator for reef set ups

 

[NanaReefer]

Sweet! So I have about 49g total water volume. Sounds good to me