Water - The Environment
How much Fresh Water is There in Your Tanks
Written by Monday, 14 May 2001 02:00
OK, you are religiously doing your water changes and you feel you have done your duty. However there is still a large amount of old water in your tank. How much? The tables below give you the answer. The blue square at the top left corner is the hypothetic amount of water you change in every water change. The top row (horizontal axis) indicates the weeks (or days if you do daily changes) after we start counting. At day 0 we assume that all the water in the tank was fresh. The first column (vertical axis) shows you the age of the water present in your tank after each change. Thus, in the 10% water change table we can see that after 4 changes (a month), you have 66% of water aged 4 weeks.
What's more, after the 7th water change, there is still a 48% of water aged 7 weeks - almost half your water volume. The cells shaded with a green color indicate the percentage of water which is over a month old. As you can see, with 50% weekly changes there is almost no water aged over 6 weeks, while at 80% weekly changes there is almost no water aged over 4 weeks (less than 2%). I hope these tables will help you to evaluate the size of your water changes. The idea to build these tables was given to me by an article of D.A.Boruchowitz which appeared in TFH, issue 530.
|
10% |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
|---|---|---|---|---|---|---|---|
|
Fresh |
10 |
10 |
10 |
10 |
10 |
10 |
10 |
|
1 |
90 |
9 |
9 |
9 |
9 |
9 |
9 |
|
2 |
|
81 |
8,10 |
8,10 |
8,10 |
8,10 |
8,10 |
|
3 |
|
|
72,90 |
7,29 |
7,29 |
7,29 |
7,29 |
|
4 |
|
|
|
65,61 |
6,56 |
6,56 |
6,56 |
|
5 |
|
|
|
|
59,05 |
5,90 |
5,90 |
|
6 |
|
|
|
|
|
53,14 |
5,32 |
|
7 |
|
|
|
|
|
|
47,83 |
|
20% |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
|---|---|---|---|---|---|---|---|
|
Fresh |
20 |
20 |
20 |
20 |
20 |
20 |
20 |
|
1 |
80 |
16 |
16 |
16 |
16 |
16 |
16 |
|
2 |
|
64 |
12,8 |
12,8 |
12,8 |
12,8 |
12,8 |
|
3 |
|
|
51,2 |
10,24 |
10,24 |
10,24 |
10,24 |
|
4 |
|
|
|
40,96 |
8,19 |
8,19 |
8,19 |
|
5 |
|
|
|
|
32,77 |
6,55 |
6,55 |
|
6 |
|
|
|
|
|
26,21 |
5,24 |
|
7 |
|
|
|
|
|
|
20,97 |
|
30% |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
|---|---|---|---|---|---|---|---|
|
Fresh |
30 |
30 |
30 |
30 |
30 |
30 |
30 |
|
1 |
70 |
21 |
21 |
21 |
21 |
21 |
21 |
|
2 |
|
49 |
14,7 |
14,7 |
14,7 |
14,7 |
14,7 |
|
3 |
|
|
34,3 |
10,29 |
10,29 |
10,29 |
10,29 |
|
4 |
|
|
|
24,01 |
7,20 |
7,20 |
7,20 |
|
5 |
|
|
|
|
16,81 |
5,04 |
5,04 |
|
6 |
|
|
|
|
|
11,76 |
3,53 |
|
7 |
|
|
|
|
|
|
8,24 |
|
40% |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
|---|---|---|---|---|---|---|---|
|
Fresh |
40 |
40 |
40 |
40 |
40 |
40 |
40 |
|
1 |
60 |
24 |
24 |
24 |
24 |
24 |
24 |
|
2 |
|
36 |
14,4 |
14,4 |
14,4 |
14,4 |
14,4 |
|
3 |
|
|
21,6 |
8,64 |
8,64 |
8,64 |
8,64 |
|
4 |
|
|
|
12,96 |
5,18 |
5,18 |
5,18 |
|
5 |
|
|
|
|
7,78 |
3,11 |
3,11 |
|
6 |
|
|
|
|
|
4,67 |
1,87 |
|
7 |
|
|
|
|
|
|
2,80 |
|
50% |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
|---|---|---|---|---|---|---|---|
|
Fresh |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
|
1 |
50 |
25 |
25 |
25 |
25 |
25 |
25 |
|
2 |
|
25 |
12,5 |
12,5 |
12,5 |
12,5 |
12,5 |
|
3 |
|
|
12,5 |
6,25 |
6,25 |
6,25 |
6,25 |
|
4 |
|
|
|
6,25 |
3,13 |
3,13 |
3,13 |
|
5 |
|
|
|
|
3,13 |
1,56 |
1,56 |
|
6 |
|
|
|
|
|
1,56 |
0,78 |
|
7 |
|
|
|
|
|
|
0,78 |
|
80% |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
|---|---|---|---|---|---|---|---|
|
Fresh |
80 |
80 |
80 |
80 |
80 |
80 |
80 |
|
1 |
20 |
16 |
16 |
16 |
16 |
16 |
16 |
|
2 |
|
4 |
3,2 |
3,2 |
3,2 |
3,2 |
3,2 |
|
3 |
|
|
0,8 |
0,64 |
0,64 |
0,64 |
0,64 |
|
4 |
|
|
|
0,16 |
0,13 |
0,13 |
0,13 |
|
5 |
|
|
|
|
0,03 |
0,03 |
0,03 |
|
6 |
|
|
|
|
|
0,01 |
0,01 |
|
7 |
|
|
|
|
|
|
0,00 |
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