# ?? How many gallons per inch water level in a 75 gallon



## DKShrimporium (Nov 23, 2004)

Hi all, newbie here.

Anyone have the figure for how many gallons a one inch drop in water level represents in a perfecto 75 gallon tank? Or the figure for how many cubic inches water to a gallon? I figured it would be a useful thing to know, so when I do water changes I can do them in inches, then convert that to gallons, so I know how much dosing to put into the replaced water.

I apparently have very low GH and KH and so will be supplementing my water at each change to provide buffering capacity. I'm on the learning curve here and trying to figure out what I'm doing.

Thanks for your help!

Donna


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## observant_imp (Jun 30, 2004)

cubic inches / 231 = gallons


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## Wasserpest (Jun 12, 2003)

There are two simple ways to figure that out:

For a 75 gal tank, the real volume will be around 70 gals (measure the *inside* dimensions of the tank, multiply them and divide by 231). Divide this number by the height of the tank, and you will get your gallons per inch. 

Or, take a bucket that fits 5 gallons, mark the tank water level, fill the bucket, and mark the new level. The difference between the two marks will be 5 gallons, and you can put some more marks on the side of the tank for future measuring purposes.


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## DKShrimporium (Nov 23, 2004)

*Thanks*

Thanks guys,

I think I'll do it by calculating. I do have a 5 gallon bucket, but I don't know exactly the fill line on it that would make it 5 gallons. I can easily do the measuring thing.

Donna


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## TeeItUp (Mar 18, 2004)

Wasserpest said:


> There are two simple ways to figure that out.


How about a third way. 

If the tank is 75 gallons (or say it has a useful load of 70 gallons), divide the gallons by the height of the tank to water level and that is how many gallons there is in 1”.


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## Rex Grigg (Dec 10, 2002)

greenisgood said:


> Thanks guys,
> 
> I think I'll do it by calculating. I do have a 5 gallon bucket, but I don't know exactly the fill line on it that would make it 5 gallons. I can easily do the measuring thing.
> 
> Donna


Easy to figure out on the bucket. Get your measuring spoons and put 3840 teaspoons of water in the bucket. That will be the 5 gallon line. Of if you want you could just use a gallon milk jug and put five of those in the bucket.


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## Wasserpest (Jun 12, 2003)

TeeItUp said:


> How about a third way.
> 
> If the tank is 75 gallons (or say it has a useful load of 70 gallons), divide the gallons by the height of the tank to water level and that is how many gallons there is in 1”.


That's what I meant to be the first method. :icon_idea


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