Re: [Killietalk] Flow thru systems

[Barry Cooper <bjc3 at centurytel_net>]

John,

I'll be writing a full article on this co-authored with Lee Harper, 
describing our approaches to automatic water change, flow through systems. 
I don't want to submit it for a few weeks, until I get a good feel for the 
benefits (and disadvantages?). However, my impressions to date are 
positive. I'll describe what I've done very briefly.

My old system was flow-through recirculating, with a sump under each rack 
of tanks. This required UV irradiation on each rack and I still didn't seem 
to find the time to change the water in the sump, which was the original 
idea. I also had a feeling that my fish weren't doing as well as they should.

The new system is a flow-through exchange system. Water from a reservoir 
(300 gal tank) is pumped to the distribution system, built from 3/4" PVC. I 
have 8 stations. Each is fed via a Rainbird solenoid valve. The system is 
pressurized using a shallow well pump, which draws water from the 
reservoir. This allows me to treat the water before use. The stations (i.e. 
the solenoid valves) are controlled by a Rainbird controller, all these 
items being normally used to control irrigation/sprinkler systems. I can 
regulate the amount of water fed into the tanks by the time that the water 
is allowed to flow. For example, I use 2 mins daily for my fry tanks, 8 
mins for racks of 5 gal tanks, and so on. This is calibrated by trial and 
error to provide an inflow of 10% for each tank. That is effectively less 
than 10% exchange, because there is some mixing. I run most tanks four 
times a week, giving a total of 40% inflow. I am still playing with this 
and may go to five times a week, or a bit more exchange per run. The 
advantage of a couple of days rest a week, for me, is that I can refill the 
reservoir, add salt, Equilibrium, etc. and allow it to dissolve and stabilize.

So far I am very happy and impressed with how this is working, with five 
racks so far fully hooked up. The fish already seem livelier to me. I would 
possibly do one thing differently if I were doing it again, and that is to 
use the low pressure solenoid valves sold by Rainbird. The ones I have 
require 15 psi to operate. They sell valves for drip irrigation systems 
that will operate at 3.5 psi. That would mean I could use a submersible 
pump to pressurize the system. The shallow well pump produces 30-50 psi. I 
stabilize that by having a 30 psi pressure regulator inline. I use a valve 
to reduce flow to the fry boxes so that I don't blow them out of the water, 
literally.

Water flows out of drains in the tanks, which are drilled, into a drain 
system, to the outside. I hope this summer to build a pond outside my 
fishroom into which I can run that water.

More in some future issue of JAKA.

Barry
At 10:04 AM 1/13/2004 -0600, you wrote:
> Barry,
>
> On 13-Jan-04 Barry Cooper wrote:
> > it is fully automated,
> > controlled by a timer and does water changes of about 10% four times a 
> week
> > on my breeding and grow-out tanks, and every day on my fry boxes.
> >
> Is there any information on how you did your automatic water changer???
>
> Continuous flow fry systems are the thing but adding a auto water changer to
> mine is my next goal.
>
> john
> ------------------------------------
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> Andante Systems               o
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_____________________________________________________________
Barry J. Cooper, Prof. Emeritus, Dept. Biomedical Sciences, Cornell University
Professor, College of Veterinary Medicine, Oregon State University
Home address: 27505 Riggs Hill Rd., Sweet Home, OR 97386 


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