Tank Cleaning

three-fingers · Aug 13, 2009

If stats and fish are all fine carry on the way you are.

I do 30-50% weekly on my marine nano and high-tech planted, ~20% every month or two on my 190L planted and basically just top up my planted betta tank with RO water and/or water from the high tech planted tank as needed.

But I'm hardly strict with any of this...

Rediahs · Aug 14, 2009

KingOfTheSea said:
I usually split a 30%-50% waterchange into 2 over a week. So 2 15%-25% water changes a week. Works fine, fish stay healthy

Not to burst your bubble, but two 15% or 25% water changes aren't equivalent to one 30% or 50% change.

You actually have to change MORE water than you'd think, to come to an equivalent number, because if you think about it, it only makes sense. Say you are changing 10% twice a week for what you BELIEVE to be a total of 20%. The first time in the week that you change 10%, you have removed 10% of the tank's old water and replaced it with new water. The SECOND time, however, when you remove 10% of the water, 10% of THAT water is the water you just added earlier that week, so it isn't all old water that you're removing. This makes two 10% changes equivalent to 10% + (90% of 10% = 9%) = 19% instead of 20. Okay, so this doesn't seem like a lot, but when you go to larger amounts, it makes more of a difference.

Say you change 30% twice a week. You'd hope that you're changing 60% of the water. Instead, you're changing 30% + (60% of 30% = 18%) = 48% instead of 60! That's a whole difference of 12%. Two 30% changes a week don't even change 50% of the water yet. You'd need to go higher, maybe 35%, to reach 50.

Don't know if you knew this or not, just a side note... I hear people say that they like to space their water changes out to make it easier for fish, but you have to remember that you have to change a little MORE water than usual.

TheSims3Dude · Aug 14, 2009

Super Dude said:
13 fish.

13 blood thirsty, messy pirhanas or 13 tiny little neons? lol

proper mantainance is different for every setup. assuming an average setup, 20% should suffice.

Lol, no I have mostly livebearers in my tank, like I said, I do between 15-25% of the water once a week, my stats are always fine though, so I think if something is going good, just keep it that way... eh?

Lisa1981 · Aug 14, 2009

I do 50% every 7 - 10 days on my main tank and 90% on my 5g Betta tank.

TheSims3Dude · Aug 14, 2009

Ya, my tank is a 20 gallon, (US) so I thought 15-25% once a week would be enough, I usually do it every Sunday.

EDIT:
Is it true that to much of a water change or too often can shock your fish? I always wondered that.... :blink:

OldMan47 · Aug 15, 2009

I try to do about a 20% weekly change on my tanks but sometimes miss a week. The 20% is enough on the tanks that I have because they are fairly lightly populated. If I had the heavy stockings that I have seen advocated by some people here, I would do at least a 50% weekly water change and expect real trouble if I missed a week. As AndyWatson said, a lot depends on what is in your tanks.