# Unit conversion

by bprku
Tags: conversion, unit
 P: 2 Hi, I ma having problem, can anyone help me converting ""individual/liter to individual/square meter" for example 20 fish/L = ?? fish /m2
 Sci Advisor HW Helper P: 4,300 Well, liter is a measure of volume (1 liter is 1 dm3), and square meter is a measure of area. So you are still missing some information.
 P: 2 well, I dont agree with you since this is the measure uses in biology. let me give you answer, if you go to a lake with a 1 liter cylinder and catch 20 Daphnia. so its clear that you have 20 daphnia/L. Now the question is how many daphnia will be in one square meter. if you think this isa stupid question real some articles publishes in aquatic biology"http://www3.interscience.wiley.com/cgi-bin/fulltext/119081299/PDFSTART"
HW Helper
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P: 2,841
Unit conversion

 Quote by bprku Hi, I ma having problem, can anyone help me converting ""individual/liter to individual/square meter" for example 20 fish/L = ?? fish /m2
In the strictest of theoretical sense, you cannot make that conversion. Do you have a particular practical application which would be simpler if you were to make such a conversion?

The reason why in theory you can not make the conversion is that Liter is a unit of volume (or space), and square meter is a unit of area (or surface). The DIMENSIONs do not match.

Do you have a situation in which you may safely ignore one of the physical measurements in order to use area instead of volume?
 Sci Advisor HW Helper P: 4,300 I cannot access your link, even through my institutions' website. Also I do not think it is a stupid question, I just think it is a meaningless question until you give us the "hidden" information. Here's an analogous question for you: Suppose one bucket of paint suffices for 40 square meters, and my house is 20 meters long. How many buckets of paint do I need to paint the outside wall?
Mentor
P: 41,320
 Quote by bprku well, I dont agree with you since this is the measure uses in biology. let me give you answer, if you go to a lake with a 1 liter cylinder and catch 20 Daphnia. so its clear that you have 20 daphnia/L. Now the question is how many daphnia will be in one square meter. if you think this isa stupid question real some articles publishes in aquatic biology"http://www3.interscience.wiley.com/cgi-bin/fulltext/119081299/PDFSTART"
Your link appears to be to a site that requires joining or paying to view whatever articles you are referring to.

As others have stated, your question is not answerable without a bit more information. Your example of a liter bottle with 20 items in it does not help. When you say "per square meter", are you perhaps thinking of looking down into the water, and seeing fish below a 1 square meter grid? If you have a volume density of something, you will need the depth of the water to know how many of whatever is below a 1 square meter grid.
 P: 1,127 I should guess he is referring to ponds where fish density was once measured as fish per acre of bottom. I suppose he is now referring to smaller ponds (or perhaps a more manageable number) when he uses fish per square meter. There would be no conversion applicable for ponds since depth doesn't have the same meaning as in lakes. You could use an average depth to get the liters, but I think that might be misleading.
 Mentor P: 22,315 It is also possible that it is just an error and s/he is actually looking for fish per cubic meter...
 P: 1,127 Is that blue fish or red fish?