Calculating Gallons of water in tank

[sen5241b]

Somebody said there was a formula you could use to determine the gallons of water in your tank. It involved adding a specific amount of fresh water and then determining how much the salinity had changed. Anyone have this formula?

 

[ccCapt]

Not sure about any forumla to determine the difference between the volume of saltwater vs the volume of fw.
Here's the RC tank volume calculator.

 

[Hornet]

Here's another calculator that figures in sandbed and live rock:
Garf Tank Water Volume Calculator

If you find a link explaining the process you mentioned post it. I'd like to read how to do something like that.

 

[sen5241b]

I had to look around a little but this is it:

http://www.reefbuilders.com/forums/reef-discussion/11208-calculating-water-volume-tank.html

You'll need a good refractometer.

 

[ccCapt]

I don't get it. What's the point? Why do you want to know, or even need to know the difference in volume between sw and fw?

 

[Hornet]

I don't get it. What's the point? Why do you want to know, or even need to know the difference in volume between sw and fw?

In his original post he says FW but I think he actually meant RO/DI. He just talking about using the change in salinity to figure up tank volume.

sen5241b thanks for posting the link. I read the posting and I plan on doing it next time I add RO/DI to the tank. I think it will be a nice experiment to involve the kids in and figure up my exact total tank volume. In theory it seems like it should work.

 

[sen5241b]

In his original post he says FW but I think he actually meant RO/DI. He just talking about using the change in salinity to figure up tank volume.

sen5241b thanks for posting the link. I read the posting and I plan on doing it next time I add RO/DI to the tank. I think it will be a nice experiment to involve the kids in and figure up my exact total tank volume. In theory it seems like it should work.

Correct. I want to know how much water is my SW tank so I can figure out exactly how much water to mix for a X% water change. When I change out 5Gs now I really don't know what percent of the water was changed. This information could also make dosing easier.

 

[ccCapt]

I still don't get it, but anyway, does it really make a difference if you do a water change and it's 9% or 10.5%? Not sure how you do water changes, but I have a 20g tank. I fill it with RO/DI and mix in my salt, etc. I then drain 4 5g jugs from my tank and replace it with the fresh mix. I don't know if it's a 12%, 15%, 17.5% or whatever. It doesn't really matter, does it?

Dosing is far from an exact science. If you enter 26g or 27.75g total volume in the Reef Chemistry Calculator, you won't get a big difference in the amount to dose. You get a general idea and then test, test and test.

IMO, very few things need to be done in exact amounts. Your basic salinity, pH, calcium, alk and mag have pretty wide zones that are acceptable. But, if you run ozone, use co2 (calcium reactor), or dose carbon (vodka, sugar, etc) you better be exact in your dosages/monitoring. They can wipe out a tank in hours.

 

[sen5241b]

I still don't get it, but anyway, does it really make a difference if you do a water change and it's 9% or 10.5%? Not sure how you do water changes, but I have a 20g tank. I fill it with RO/DI and mix in my salt, etc. I then drain 4 5g jugs from my tank and replace it with the fresh mix. I don't know if it's a 12%, 15%, 17.5% or whatever. It doesn't really matter, does it?

Dosing is far from an exact science. If you enter 26g or 27.75g total volume in the Reef Chemistry Calculator, you won't get a big difference in the amount to dose. You get a general idea and then test, test and test.

IMO, very few things need to be done in exact amounts. Your basic salinity, pH, calcium, alk and mag have pretty wide zones that are acceptable. But, if you run ozone, use co2 (calcium reactor), or dose carbon (vodka, sugar, etc) you better be exact in your dosages/monitoring. They can wipe out a tank in hours.

Yeah, most of the time precision is not necessary with marine tanks but for my 29G tank I really don't know if I have 25Gs of water or 20 but I want to know. I can't say how much LR I have in there --I didn't weigh it as I incrementally added it over the course of a year.

 

[Hornet]

Yeah, most of the time precision is not necessary with marine tanks but for my 29G tank I really don't know if I have 25Gs of water or 20 but I want to know. I can't say how much LR I have in there --I didn't weigh it as I incrementally added it over the course of a year.

I'm of the same opinion as you. I know things don't always need to be exact but I think it would be nice to figure up exactly how much water volume is in my tank.

Thanks for sharing sen5241b. I'll make use of the information.