Measurements for a newbie

[Bruce Leyland-Jones]

I get what Colin means. If there's no decor in the tank, you measure the width and length then the height from the top of the substrate to the water surface. That gives the volume of water. Then when the decor is put in, the water surface goes higher but the amount of water stays the same.

Question - when measuring width and length, is it usual to measure from the outside edge of the glass or the inside edge? My main tank is made from 10 mm glass so the outside measurements are 2 cm (almost an inch) more than the inside measurements. That alone makes a difference of 12 litres for my tank.

Colin's method fails to take into account what happens when, as you add the hard landscaping, the tank overflows.
Been there, done that, got moist...once.
It's also a lot, lot easier to arrange the hard landscaping when there's no water in the tank...or are you wasting a whole tank's worth of water, just to measure it's volume?

 

[Colin_T]

Again, all you are doing is measuring the capacity of the tank and not the amount of water you'll have to be working with, day in, day out.
The internal volume of the tank reduces when you put things in it and, whilst we can tentatively ignore the mass of fish and plants, ignoring the volume taken up my hard landscaping would be foolish.

Again, when setting up a tank, the absolute simplest method is to to measure the amount of water you put into it, after you've added substrate and rocks, etc..

go back and read post 10, all of it.;

 

[Essjay]

I usually use the inside measurement, I wondered what other people did.

Colin's method says if you have wood, rock ect already in the tank, take them out, measure the water from top of subtsrate to surface, then put the rocks etc back.

 

[Bruce Leyland-Jones]

go back and read post 10, all of it.;

I did...repeatedly.
Your method adds nothing but extra and unnecessary steps.

 

[Essjay]

It's a useful way for those who didn't measure the water in when they set the tank up then suddenly find they need to now the volume. The other option would be to drain the tank down to the substrate then refill it, measuring how much water that takes.
But yes, measuring water in when the tank is set up is the easier way.



Hmmm, I wonder how much water mine holds. It took 188 litres when I set up the tank, but since then I've replaced several small bits of wood with two big ones.........

 

[Bruce Leyland-Jones]

It's a useful way for those who didn't measure the water in when they set the tank up then suddenly find they need to now the volume. The other option would be to drain the tank down to the substrate then refill it, measuring how much water that takes.
But yes, measuring water in when the tank is set up is the easier way.



Hmmm, I wonder how much water mine holds. It took 188 litres when I set up the tank, but since then I've replaced several small bits of wood with two big ones.........

So did the water level change when you did that...or not?

 

[Essjay]

I did it during a water change. I didn't occur to me to count how many bucketfuls of water I used to refill it afterwards

 

[Myraan]

Um..didn't Colin mean to fill tank with decor.... then remove decor to cause the level to drop slightly, then measure the physical volume the water takes up in in geometric space, then return decor?

Basically a way to get the same number without completely emptying the tank first.

And if you a using capfuls you are only guessing anyway, so just be careful to slightly underdose unless you know an overdose of the chemical is harmless anyway?