I change the water on my tanks every 1-2 weeks; I aim for every week, but often enough I get lazy and skip a week here and there. On quantity of water changed, I abide by the philosophy of "More is Better". I usually change about 70-90% of a tank's water each time.
My reasoning behind this is: Nitrates/other unidentified contaminants are fairly evenly dispersed throughout the water in the tank-- *this is just my personal theory, I have no hard evidence to support it, it just seems reasonable*. Therefore, the only way to get rid of this bad stuff is to remove as much water as possible.
The potential problem with this method is
1) maintaining consistent tank temperature during the water change, and
2) the assumption that the parameters of the incoming fresh water are roughly equivalent to the parameters of the old water
Fortunately in my area of residence, the water seems to be extremely consistent, so I don't personally have to worry about #2, although that isn't to say an odd serious change won't ever happen.
#1 is a regular issue for me though, as during the winter my fresh water outlet comes in at 55-60F more often than not, which is certainly bad for 75-80F tropical fish tanks. I circumvent this by chasing the fish over to one end of the tank, and adding periodic half-gallons of 120F sink water. Unfortunately, this past week I got sloppy and didn't notice that two of my catfish in my 200g were hiding under decor in the hot-water-addition zone. I completely fried a 2 yr old 5" spotted pictus, and my 5" S. eupterus is barely clinging to life as I type (I hope I don't find him dead when I get home
Anyway, the trade off for these risks is that toxins/contaminants in my tank are virtually nonexistent, which is just absolutely awesome in my book
Its a great feeling to do a nitrate test after a water change and see that your nitrates are at 5 ppm.
My reasoning behind this is: Nitrates/other unidentified contaminants are fairly evenly dispersed throughout the water in the tank-- *this is just my personal theory, I have no hard evidence to support it, it just seems reasonable*. Therefore, the only way to get rid of this bad stuff is to remove as much water as possible.
The potential problem with this method is
1) maintaining consistent tank temperature during the water change, and
2) the assumption that the parameters of the incoming fresh water are roughly equivalent to the parameters of the old water
Fortunately in my area of residence, the water seems to be extremely consistent, so I don't personally have to worry about #2, although that isn't to say an odd serious change won't ever happen.
#1 is a regular issue for me though, as during the winter my fresh water outlet comes in at 55-60F more often than not, which is certainly bad for 75-80F tropical fish tanks. I circumvent this by chasing the fish over to one end of the tank, and adding periodic half-gallons of 120F sink water. Unfortunately, this past week I got sloppy and didn't notice that two of my catfish in my 200g were hiding under decor in the hot-water-addition zone. I completely fried a 2 yr old 5" spotted pictus, and my 5" S. eupterus is barely clinging to life as I type (I hope I don't find him dead when I get home
Anyway, the trade off for these risks is that toxins/contaminants in my tank are virtually nonexistent, which is just absolutely awesome in my book
Its a great feeling to do a nitrate test after a water change and see that your nitrates are at 5 ppm.
