# Re: [Killietalk] Turnover rates

```When looking at drip water replacement systems I look at the math
differently. We don't care if we have new or old water molecules in our
tanks. We want to remove the waste products and impurities. We do that by
changing the water.
To understand my thinking visualize a ten gal. tank with 9 gals. of water
and waste. Now we add 1 gal. of water and completely mix it in. We then
remove one gal. I contend this removes 10% of the waste. (One gal divided by
10)

Thus  if we mix well we can assume a formula A/(A+O)=C
Where A = added water, O = original water, & C = % change.

Most of us add water on the opposite side of the tank from the overflow and
the newly introduced water drops need to travel across the entire tank most
likely past an air driven filter which does a very good job of mixing. The
first drop of water removed in an overflow system hasn't had the benefit of
mixing and the last drop has. This means that the drip water changing system
is more efficient then the formula for a batch process as described above.
It is probably the average between 1/9 & 1/10 or 10.5 %.
Vince
----- Original Message -----
From: "Markus Brown" <thefishbiologist at charter_net>
To: "Killitalk" <KillieTalk at aka_org>
Sent: Thursday, November 10, 2005 10:47 PM
Subject: [Killietalk] Turnover rates

> Hello All!
>
> For those who are currently using recirculating or flow through/single
> pass systems, how much water do you personally use for a particular tank
>
> I have always tried to make sure the water mixes once every few hours,
> with some kind of circulation in each tank i.e an airstone, or sponge
> filter. Things have always worked out fine, I am just curius as to other
> opinuns on the matter?
>
> Also, I have always used P.R Escobal's calculaion for what he calls, turn
> over rate. The formula teaches that even though you may be putting 20
> gallons of water into a tank in an hour, you are NOT replacing the water
> twice an hour, you are mearly mixing the "filtered" water with the
> un-filtered water. Using this calculation: T=9.2 (Gallons in vessle/ Water
> flow delivered to the vessle) where the 9.2 is a a purity coeficiant
> equaling 99.99 % and using my earlier example of a ten gallon tank,
> reciving 20 gallons an hr, the true turnover rate would be once every 4.6
> hours.
>
> Any thoughts on the matter?
>
> Markus Brown
> Astoria, Or
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