who is good with calculations?

[petluvr]

Well, I'm not going to do math for you (unless you pay me in beer) ... but here's a link to a calculator that will figure it out for you. This one factors in different tank shapes and equipment setup options. Enjoy!

http://reef.diesyst.com/volcalc/volcalc.html

WOW Kashta I would have thought you would have linked the op to an ac calculator
http://www.aquariacentral.com/forums/calc.php

 

[DGalt]

figure the volume of your sump (121 x 47 x 40 = 227480 cm^3), which holds 60 gallons.

29 gallons is about 50% of your sump. So basically you're going to want to change the water in 1/2 of your sump. Am I interpreting what you're saying properly?

So your line would be 1/2 way down the sump (20 cm below the top). That'll give you about what you want (you can figure it out if you want it to be exactly 29 gallons. 29/60 * 40 = 19.33333333....cm, so your line would be 19.3cm below the top)

don't over complicate things

 

[fwiffo]

i was recallling some volume formulas from calculus myself but was too tired to do them!!!

i would go with zigman's work myself. good enough for what is being done.

 

[Cluunox]

well if your water depth in the sump is 40 cm and that gives you 60 gl then to remove 29 gl i would bet you need to go to a depth of about 21 cm because you are just short of half the total amount (30 gl) which would be 20 cm. just back yard figuring though. so 40 - 19 = 21cm

my bad i told him what he had left not what he should take out but the amount seems to end up the same.

 

[thesoul2008]

thanks guys you all seem to come to the same conclusions got it pretty much sorted