confusion on water changes

mkbyrne

AC Members
Jun 2, 2009
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help! this is my first aquarium, a 20 gallon long. i have both read and heard different thing concerning water changes, some say 10% every week. some say 25% every two weeks, and yet others say 25% once a month. which way do you guys suggest and why?

inhabitants:
4 swordtails 3 female 1 male
1 tequila sunrise guppy
1 fancy male guppy
1 angel (nickel sized)
1 dwarf gourami

thanks in advance for your help.
 
once a week in a definite. For that load I'd do something like 50% one week, then 25% the next week. Another way to judge is just by paying attention to the water. If its looking bad change more water... if it smells bad, same thing.
 
The frequency and amount of water changes depends mainly on two factors: Your level of filtration, and your stocking. The more stock, the more water needs to be changed. The less filtration, again the more water needs to be changed.

In my opinion if you are overfiltering and lightly stocked, it isn't as necessary to change once a week. If the water parameters are staying in pristine levels, then the only real concern are the levels of TDS, or total disolved solids, that need to be replaced in the water column from time to time. In my mature tanks I often will only replace the water lost when I siphon out any wastes.

To determine what you need to do as far as water changes, can you please share your filtration, the age of the tank, and current parameters?

At first glance, I would say you are a bit overstocked for a 20.

Kristina
 
Knowing your filtration certainly helps, but for the most part, 25% weekly is a good place to start, and you can adjust from there.
 
I would do at least 50% weekly with your current setup.
 
i agree with the others, a 25 to 50% change is necessary once per week to keep your tank and fishes healthy, and a good gravel vacuum every couple weeks and filter cleaning at least once a month. never clean your filter on the same day you gravel vac, so as to preserve as much of the beneficial bacteria as possible.
 
The Why Part:

We change water to rid our water of Nitrate build up mostly. Once you have a feeding schedule set and maintenance set, A good way to get an idea if what you are doing is sufficient is keep a log of your water tests.

Watch the nitrate build up is mainly the basic way to do this. See what your readings look like during the week. On change out day, test before and after the change. See how much you impacted the readings.

Getting a general idea of build up rate with your feeding schedule will give you a ballpark figure on how much to change water weekly. Adjust according to how your readings look. Also keep in consideration that some municipal water sucks like mine. TDS readings flux from 60-100 from what I was told by a local reefer. High nitrate water source defeats the purpose of water changing. You may not have that problem but keep this in mind.
 
The angel needs about 10 gallons all to itself and needs cleaner water than the guppies and swordtails. 25% or more should be a weekly minimum for the health of all the fish. Doing so will develop good maintenance habits. You will also find problems faster from good maintenance as that is an ideal time for tank inspection and inspection of stock. Doing marginal maintenance is asking for trouble.
 
Get a liquid test tube kit. Check for nitrates weekly and when they get to 20 ppm do a 50-75% water change. It may be every week (doubtful) or it may be every 2 wks.
 
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