is there a formula to calculate how much soil to use?

tlyons01 · 05-01-2012, 02:21 PM

I am going to be converting my 46 gallon tank to a dirted tank with PFS cap, but I haven't any idea how much soil it will take for the task. Is there a calculation I can use that anyone can share with me, so that I may get the right amount from the get go and not want to kill myself later? I appreciate any help

Regards, Therese

kamikazi · 05-01-2012, 04:17 PM

Most people use 1 to 1.5 inches of soil and a 1.5-2 inch cap.

If you measure the length and width of your tank you can get the area, then put in the depth of soil you want and you can get a volume of soil.

I got the big bag of organic choice potting mix (32 quarts I believe) and I have about half the bag left over. After setting up my 40 gallon acrylic tank (which I think is actually more like a 37 gallon tank)

One big bag should be enough for a 46 gallon tank. But if you were concerned and didnt want to go back out to the store if you came up short you could get 2 bags. Then you will have extra for another tank or some other garden project.

As far as PFS goes, I can't really advise on how much you'd need b/c I capped with pea gravel. But the formula would work the same way. My guess would be 2 bags of sand.

tlyons01 · 05-01-2012, 04:59 PM

Thanks kamikazi. I already have the sand, it is what I am currently using. I wondered about the dirt, because I found a site that sells bags of soil at 3lbs per bag. I was trying to figure out how many bags I should be getting. They say on the site that 3 lbs is enough to set up a 10 gallon tank. What they do not say is how thick that makes the dirt. They could be referring to only 1/4 of an inch or more, there is no way to know, I guess. I would llike to use at least 1", but maybe as much as 1.5".
I will try your formula for volume and see if that works for me, I was always good at math IN GRADE SCHOOL!!!

Diana · 05-01-2012, 11:13 PM

Length x width x depth, all measured in the same units. For example, feet.

A tank that is 3' long, x 1' wide with 2" of substrate (mumble... mumble... 2" = .17 of a foot) = .5 cubic feet of material.

Now, convert gallons to cubic feet...
There are 7.5 gallons per cubic foot, so half a cubic foot = 3.75 gallons.
You can multiply that by 4 to get quarts (potting soil is often labeled in quarts): 3.75 x 4 = 15 quarts.

Sand and gravel weigh pretty close to 100 lbs per cubic foot, so if you are using sand or gravel you would need about 50 lbs.

Brian Mc · 05-02-2012, 06:51 AM

There is a pretty sweet calculator built right in here at TPT, could use a few more options like AS though:

http://www.plantedtank.net/substratecalculator.html

Diana · 05-02-2012, 02:20 PM

Liters are so close to quarts that you can use the formulas that give you the answer in quarts to see how many liters to buy. Or simply measure everything in centimeters. 1000 cubic centimeters = 1 liter.

05-01-2012, 02:21 PM	#1
tlyons01 Planted Tank Enthusiast (View User Tanks) PTrader: (9/100%) Join Date: Nov 2011 Location: Clarksville, TN Posts: 682	is there a formula to calculate how much soil to use? I am going to be converting my 46 gallon tank to a dirted tank with PFS cap, but I haven't any idea how much soil it will take for the task. Is there a calculation I can use that anyone can share with me, so that I may get the right amount from the get go and not want to kill myself later? I appreciate any help Regards, Therese __________________ totally obsessed 46 G bowfront Fraternity of Dirt #75 ~~Mud Pies~20 gallon~~ Last edited by tlyons01; 05-01-2012 at 02:22 PM.. Reason: spelling

05-01-2012, 04:17 PM	#2
kamikazi Planted Tank Guru (View User Tanks) PTrader: (5/100%) Join Date: Sep 2010 Location: Lincolnton, NC Posts: 2,246	Most people use 1 to 1.5 inches of soil and a 1.5-2 inch cap. If you measure the length and width of your tank you can get the area, then put in the depth of soil you want and you can get a volume of soil. I got the big bag of organic choice potting mix (32 quarts I believe) and I have about half the bag left over. After setting up my 40 gallon acrylic tank (which I think is actually more like a 37 gallon tank) One big bag should be enough for a 46 gallon tank. But if you were concerned and didnt want to go back out to the store if you came up short you could get 2 bags. Then you will have extra for another tank or some other garden project. As far as PFS goes, I can't really advise on how much you'd need b/c I capped with pea gravel. But the formula would work the same way. My guess would be 2 bags of sand. __________________ Frat. of Dirt #3 My YouTube Channel Walstad Bowls Blackwater Paradise Expansus 15 Gal. Office 29 Gal. Blackwater Paradise 40 Gal. Crypt Utopia

05-01-2012, 04:59 PM	#3
tlyons01 Planted Tank Enthusiast (View User Tanks) PTrader: (9/100%) Join Date: Nov 2011 Location: Clarksville, TN Posts: 682	Thanks kamikazi. I already have the sand, it is what I am currently using. I wondered about the dirt, because I found a site that sells bags of soil at 3lbs per bag. I was trying to figure out how many bags I should be getting. They say on the site that 3 lbs is enough to set up a 10 gallon tank. What they do not say is how thick that makes the dirt. They could be referring to only 1/4 of an inch or more, there is no way to know, I guess. I would llike to use at least 1", but maybe as much as 1.5". I will try your formula for volume and see if that works for me, I was always good at math IN GRADE SCHOOL!!! __________________ totally obsessed 46 G bowfront Fraternity of Dirt #75 ~~Mud Pies~20 gallon~~

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05-01-2012, 11:13 PM	#4
Diana Planted Tank Guru (View User Tanks) PTrader: (0/0%) Join Date: Jan 2010 Location: Contra Costa CA Posts: 5,013	Length x width x depth, all measured in the same units. For example, feet. A tank that is 3' long, x 1' wide with 2" of substrate (mumble... mumble... 2" = .17 of a foot) = .5 cubic feet of material. Now, convert gallons to cubic feet... There are 7.5 gallons per cubic foot, so half a cubic foot = 3.75 gallons. You can multiply that by 4 to get quarts (potting soil is often labeled in quarts): 3.75 x 4 = 15 quarts. Sand and gravel weigh pretty close to 100 lbs per cubic foot, so if you are using sand or gravel you would need about 50 lbs.

05-02-2012, 06:51 AM	#5
Brian Mc Algae Grower (View User Tanks) PTrader: (2/100%) Join Date: Feb 2012 Location: Villa Rica, GA Posts: 98	There is a pretty sweet calculator built right in here at TPT, could use a few more options like AS though: http://www.plantedtank.net/substratecalculator.html

05-02-2012, 02:20 PM	#6
Diana Planted Tank Guru (View User Tanks) PTrader: (0/0%) Join Date: Jan 2010 Location: Contra Costa CA Posts: 5,013	Liters are so close to quarts that you can use the formulas that give you the answer in quarts to see how many liters to buy. Or simply measure everything in centimeters. 1000 cubic centimeters = 1 liter.