50 gallon drum, how many "aquarium gallons"

[Millepora_Maniac]

HI all,

I have a 50 gallon drum i use for water changes, and it seems that my 90 g aquarium holds less water than the barrel. Just wondering what the difference in gallons is all about.

Any insight would be helpful for me. it changes dosing requirements for the new water change water etc. Also would be good to know what is going on there.

Cheers!-MM

[corpusse]

Either your barrel is not 50 gallons or you tank is not 90 gallons. While many aquarium manufactures use the outside dimensions for calculating gallons, it's not going to be that far off.

[Millepora_Maniac]

Originally Posted by corpusse

Either your barrel is not 50 gallons or you tank is not 90 gallons. While many aquarium manufactures use the outside dimensions for calculating gallons, it's not going to be that far off.

Ihis is a 50 gallon food grade barrel. the tank is a 90 reef ready, 4 by 18 by 24...

on my 180g, it was drained nearly to half way, there is something weird about this, and i think it has to do with conversion or something.

I'm far from a greenhorn dude, lol

[WarDog]

https://www.matthewb.id.au/converter...alculator.html

[Millepora_Maniac]

Originally Posted by WarDog

https://www.matthewb.id.au/converter...alculator.html

Thanks! according to this, the drum is approximately 50g, so does that mean that the tank itself is not really 90g?

This has always baffled me.

like i said, my 180 nearly got drained to halfway for a water change, and my 90 was within 5" of the bottom of the tank (Yes, i realize there is some rock in there) but not that much! I also had to pull 1/3 of the water out of the 65 gallon that is plumbed into this system... I feel like i am pumping out 100 "aquarium gallons" and adding only 50 "Barrel gallons"

There has to be some explanation, since this 50 gallon barrel is standard size, i am assuming our aquariums are actually not holding as many gallons as they state.

interesting....

[FishyFishy!]

How much live rock do you have in it? It could very well be taking up a lot of water volume inside the tank.

My 210 probably only holds 150 gallons of water with all of my live rock in there.

Oh..and internal or external overflow?

[Dearth]

Originally Posted by FishyFishy!

How much live rock do you have in it? It could very well be taking up a lot of water volume inside the tank.

My 210 probably only holds 150 gallons of water with all of my live rock in there.

Oh..and internal or external overflow?

Very good explanation rock can displace a large volume of water
Half my 95 gallon tank is taken up by rock so at best I might have 50 gallons in it