The Whole Water Change Thing

I'm confused by something regarding water changes.

Let's say to change 25% of your 80 gal system, you mix 20 gals of water up and complete the task Monday night.

You've decreased the level of everything in your water by 25%.

Let's now say instead you change 5 gallons each night starting Monday, and don't finish the task until Thursday.

Is there a simple mathematical way to express the difference between changing 25% of your water both by a "one shot" representation, and again by a 5% per night over 4 nights method?

In my mind, by doing it over 4 sessions, you're changing newly changed water Tuesday, Wed's and Thursday; and would hence be less ideal--but I could be wrong.

Could anyone help me out here?

 

no, as the nitrates etc would diffuse to be equal throughout water. Denser concentrations always move towards less dense, so your only taking out 5% of the pollutants that
A.Built up during the day
B. Those left from previous water change.

 

OK. So are you saying the net difference b/w the two scenarios is the second is more efficient because it removes the undesirables produced Tuesday, Wed's, and Thursday?

If so, this would translate into the assumption that changing 5 gallons a week is better than changing 20 gallons once a month.

 

Thats what i would think. The benefits
A. Less stress because of change in params is lesser but more frequent
B Would maintain lower levels. (Would have nitrate going high and then dropping after large water change but decreasing a bit each day, keeping it low)
C.And would be much easier to do

 

I agree with this. changing fewer gallons more frequently will keep the overall level of undesirable compounds lower than one large change a month. Just before that one large change, pollutants will build up to a high at that time, then drastically changed, but will build up so that there will be a longer period of time when the pollutants are higher than when you do a smaller, weekly water change. This would result theoretically in a steady, slightly higher overall level of pollutants, but that level will not be nearly as high as a once a month change. Sorry if this is confusing of convoluted.

 

Not at all. Your response is concise and well thought. As is Aquaboy's. Thanks to the both of you.

 

Your welcome!! thats what im here to do! Help that is!

 

also works with the all the good stuff in new salt,trace elements,ect.....instead of letting those come to a extreme low once a month then replenished, they are replenished little by little over the month.

 

Everything you ever needed to know about water changes (and maybe a bit more )

Importance of Water Changes/Exchanges, By Anthony Calfo

 

Thanks for the info, Omard!;D