# Minimize water volume by substrate / decor mass



## Jamit (Apr 21, 2010)

Hello,
This question is for those with a mathematical mind.

I am upgrading from a 10g to a 20g long tank (30L x 12W x 12H)
I want to keep the volume of water in the 20gal as same as the 10g tank.
The question is how many lbs or cu in of substrate / decor mass I need to add in order to minimize the water I throw in, given that I can still achieve a full tank effect.


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## TomC (Apr 21, 2010)

Just curious. Why would you want to reduce the water volume? The more water, the more stable the water conditions.


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## Jamit (Apr 21, 2010)

I am not intentional to minimize the volume. Living at the top floor of a condo building with wood frame and subfloor, I am taking my precaution to minimize water damage if it ever happens. Plus, my tank stand can hold up to 200lbs.

A 10 gal tank of water weights about 80lbs if I recall it right. Given that I put some substrate, stones and other decors with a equivalent of 80lbs, the amount of water to fill a 20gal tank would be 10gal plus. ???


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## maximusfish (Sep 2, 2014)

I wouldn't worry about the tank breaking, water on the floor. As long as it is well sealed and you don't bang a chair or something into it you shouldn't have a problem. The floor can absolutely take the weight - think of the weight of your fridge! You have to be careful with putting large rocks in the tank though. If a fish tips it over so it hits the glass, or a very heavy rock with gravel under it, can cause the glass to crack. If you are using a large rock as a focal point you can put egg crate underneath to protect the bottom glass (look at the tank journal section to see an example).


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## Jameson (Oct 13, 2014)

Okay I am total noob here and have just a basic idea about tanks BUT - no offense - don't you think that if it is supposed to break, it will break and less amount of water won't change much? I mean the floor will still be ruined. And if the little greater amount can make a positive difference to your fish then I wouldn't risk it. After all it's the fish you care about right? If you couldn't hold it, you'd take smaller tank...


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## Bobsidd (Dec 28, 2012)

Depending on the density of your substrate, adding more to decrease the water volume could actually make the tank heavier. However, if you are set on reducing the volume of water in your 20 gallon to 10 gallons you would need 10 gallons of substrate and decor in your 20 gallon. You could fill your old 10 gallon tank to the top with substrate and decor then transfer that to your new 20 gallon tank. 

Having said that, I would just go with the 20 gallons of water. Sure it would make a mess if it broke, but so would 10 gallons, so you might as well go for it for the sake of your tank inhabitants.


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## Jamit (Apr 21, 2010)

Thanks for the advice. I have redo the silicone for the tank. Then will do a water leak test after it is cured. 
I agree that I should not focus on too much of the water level, every other elements (substrates, water parameters, etc) should take into consideration. I will just work with whatever I have for the aquascaping. Then run the tank with enough water.


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## kim86 (Sep 5, 2012)

Are you even allowed fish tanks in top floors of condos?


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## Jamit (Apr 21, 2010)

There is a maximum allowable gallon that we can keep in the unit.


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