Re: [Killietalk] Turnover rates

[Barry Cooper <bjc3 at centurytel_net>]

If you are interested in how much water will be changed using a drip 
system that adds NEW water to the tank, try the calculator at 
http://www.angelfish.net/DripSystemcalc.php. My system adds 10% of new 
water (actually aged in a holding tank, where I put in additives) each 
run, four times a week. according to the calculator, this amounts to 
36.26% over the four days and thus that amount per week. I think that is 
an adequate compromise, as I really can't afford to use much more water 
than that. I use a total of about 480 gals a week in my room.

What this calculator tells me is that the efficiency of such water 
change systems is quite high. Adding 10% using a drip system with input 
at the opposite end to output gives a 9.5% change. I actually add the 
water as a bolus, that is 10% over the period of several minutes. The 
water squirts into the tank and, from my observations, goes to the 
bottom of the tank (judged by its effect on peat sediment, etc.), while 
the overflow is at the top and the opposite end. I fancy that the 
exchange rate in such a bolus system is even higher as there would not 
be as much mixing during the influx.

Recirculating systems, of course, do not change any water until you 
empty the sump and refill it. Thus the volume changed would depend on 
the relative sizes of the tanks on the system and of the sumps. With 
professional systems having fluidized sand beds, trickle filters and so 
on such systems are probably quite effective. I had a sump system and 
abandoned it because I still had to get around to changing the sump 
contents, and found I was not very good at it. My flow-through system 
doesn't allow me to forget to do it.

By the way, I have no real way to determine the validity of this water 
change calculator, but it is interesting that the relative efficiency of 
the changes are not linear, but look like this:



Barry

Barry J. Cooper
Sweet Home, OR 97386



Ken wrote:

>Hi David, Marcus, Dave everyone...
>"The system exchanges ~90% of the water in each tank hourly.  Fortunately
>the engineers get to crunch the numbers I just get to tell them how to make
>it"
>
>Numbers: after reading a few well respected/experience posters on KT admit
>to a %50 weekly water change AND after reading about the virtues of a
>continuous replenishment system. I was thinking about a formula published in
>FAMA a loooooong while back that sorta mathematically discussed a
>optimal/practical replenishment rate....It is hard to describe "Exactly"
>what I am saying here but what prompted me out of my box was Dave Sanchez's
>original reply and Marcus's "rightful" challenge of my post (yep I re-read
>it, sounded like BS even to me). 
>
>The "Story problem" roughly goes something like this:
>
>Aquarist "A" changes 50% of his water weekly, Aquarist "B" changes 5% daily
>and Aquarist "C" changes 10% every 2 days...By Saturday which aquarist has
>maintained toxins at the lowest level?
>
>Intuitively it would seem the answer is "A" or for the "replenishing"
>advocates perhaps "C", but If memory serves me correctly the answer was
>"something" roughly like "B"...Again this a regression type formula since
>waste is being manufactured continually (a parabolic trend), but water is
>diluted in stages (a sawtooth trend)...Somewhere between the extremes of
>your fish swimming in tap and nada, is a sweet spot...Anyone got that
>formula? I wonder if it's the same thing as "Escobar's Formula"?...
>
>My other thought was again towards a "Hybrid" system: one that removes
>metabolic waste on a "demand basis" like a vegetative system and also
>continually replenishes a lesser amount of water for dilution/replenishment
>of other compounds,,,sorta finding a sweet spot with your water bill and
>your electric bill...the protien skimmer thing was a gas exchange
>"workaround" to deal with poor vegetative perfomance observed in trickle
>systems...
>
>Ken
>
>
>
>-----Original Message-----
>From: killietalk-bounces+ken_combs=sbcglobal.net at aka.org
>[mailto:killietalk-bounces+ken_combs=sbcglobal.net at aka.org] On Behalf Of
>David Lains
>Sent: Friday, November 11, 2005 3:06 PM
>To: 'killifish discussion list'
>Subject: Re: [Killietalk] Turnover rates
>
>Hi Markus
>
>I the Escobal's formula is best applied to a densely stocked tank without
>internal filtration.  
>
>On the smaller scale recirc systems with air filters in the tank, I like to
>think of the recirc as a way to keep a consistent water chemistry and to
>provide centralized water changes.  Yes there's is a bio filtration
>component to a central system but I doubt very much ammonia makes it out of
>the tank as the sponge/box filter and surface bacteria consume most of the
>ammonia produced in a lightly stocked tank.
>
>I'm currently designing a commercial water system for a Zebrafish rack that
>will run 100 to 200x 1 gallon tanks.  The system exchanges ~90% of the water
>in each tank hourly.  Fortunately the engineers get to crunch the numbers I
>just get to tell them how to make it.  Hopefully I'll get to keep the system
>and the rack and maybe get back into picking eggs.
>
>Best Fishes
>David Lains <}}}><
> 
>-----Original Message-----
>From: killietalk-bounces at aka_org [mailto:killietalk-bounces at aka_org] On
>Behalf Of Markus Brown
>Sent: Thursday, November 10, 2005 7:47 PM
>To: Killitalk
>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 size and
>fish load?
>
>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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