I personally do 10 to 30% water changes depending on which tank, each week

50% weekly on all my tanks sometimes 75% if they got fed well. I have heavily stocked tanks and massive filtration and no live plants and the nitrates still get to almost 20 ppm before a W/C although I haven't checked for nitrates in quite some time.

i try to keep at least one plant in the tanks i can just in case

I do 30% or more every 2 to 3 weeks, tanks are over filtered and i have lots of live plants and they are lightly stocked.

All percentages are an approximation, but should be close enough. Most tanks I try to keep a few live plants in too, but the Pacu eat them up.

Injured/Sick fish: 10% to 15% daily unless medication says otherwise.

Angels, Discus and Red Tailed Cat: 10% every other dayish. The RTC is a filth magnet.

Cichlids: Depends on stocking. For Adults I try for 2x a week on normal stocked tanks and ramp up to 3 or 4 if it's overstocked. My healthy quarantine tank tends to be overstocked on a semi-regular basis so that one gets it the most. In my experience South Americans seem to be far sturdier than Africans, so if I have to prioritize the SA's end up waiting. (Does anything kill Oscars besides other Oscars? )

Pacus: Depends on food. 40% to 60% a week, usually, but sometimes they make a complete mess of things so it ends up being a bit more often. Like this week they shredded their plants instead of eating them nicely, so I ended up doing two 30% changes to get the scuzzy out. I keep meaning to build them some sort of pool skimmer to cut that out.

Goldfish: Every 2 weeks give or take. They seem to like it better if I leave them go longer between changes.

Comets and Minnows don't survive long enough that I ever bother. I top it off when it runs low. Their basin is filtered and planted and the levels are all pretty good, but ain't like the turtles care if they're alive or not.

Koi: Normally I'd do something with the koi, but I somehow lucked out with the plants and the filtration and everything. All their levels remain at 0. The water is fine, and they all act totally healthy (eating, breeding and what have you). Unless something happens like a major power outage or they start dying (like 2 in a week or something), I ain't touching it.

Turtles: Adults, 90% when it's cruddy or every 2 to 3 weeks, for things like Red Ear Sliders, or sturdy types. Others depend on type and requirement. Diamondbacks more often since they prefer a bit of the brackish.

Discus 50-60% daily
everything else 50% twice a week.

30-50 % every Saturday.

I do 50% WC weekly...once and a while I can't stay on schedule and have to wait a few extra days and I'll change out 75%.

I change out about 50% every week on all my tanks. Usually on Sundays but lately its been whenever I have free time. The python makes it all possible.

Praise to the python!

Got to love the python

I do all my water changes every other day

I do a weekly 50% W/C and clean on all of my tanks on the weekends. On my 180g i also do a 50% W/C on wednesdays as well as on the weekends.

krytan wrote:

I do a weekly 50% W/C and clean on all of my tanks on the weekends. On my 180g i also do a 50% W/C on wednesdays as well as on the weekends.

i wouldn't do such large water changes on your 180, it could trigger a recycling

Doing water changes won't do anything to the bacteria unless you don't use a dechlorinator.

Mostlycichlids wrote:

Doing water changes won't do anything to the bacteria unless you don't use a dechlorinator.

I'm a little confused about the whole "recycling" concept caused by water changes. Where did this come from? I keep seeing references to it on the internet, blows my mind.

Anyways, I'll third MC's point. Nitrifying bacteria attach to a substrate and there are not enough drifting in the water column to affect nitrification. The only way to cause a tank to "recycle" is to kill the bacteria. Chlorine is very effective at that. Killed off the nitrifiers in both of the bioreactors at work last summer when a contractor allowed 450 gpm of chlorinated city water to drain down the sewer. 'twas not pretty...

WYite

mahemaheman85 wrote:

i wouldn't do such large water changes on your 180, it could trigger a recycling

I change that much water to keep my nitrates under 10ppm and my fish make their tank very messy. I have three plecos, an oscar and four other large messy fish in there. I have been cleaning the tank this way for a long time now and the tank is very healthy.

I do a 25% on my 5, 30s, and 55 gal twice a week. I use to do the the same for the 125, but for the last two weeks Ive been doing 40%. I just cant seem to get the water crystal clear like the rest of my tanks.

JMO