Maintaining conditioned water.

David Lains david at
Thu May 12 03:06:00 EST 2005


Hello Kelly

Can you give a little back ground on your make up water, salt dosing
system and water system?  It is difficult to control both your pH (and
alkalinity) and conductivity in one process.  Are using a conductivity
controller and dosing pump or are you maintaining the chemistry manually?

If you want to keep using the same buffer you are using I would suggest
that the conductivity of 900uS is fine for zebrafish.  I know of some labs
that keep their systems at ~2,000uS.  Overall a homeostatic environment is
more important than a specific set of water chemistry parameters.  With
your system, husbandry and chemistry I would prefer a consistent pH range
and a conductivity of 900uS over the current pH and conductivity
fluctuations.  I used to run ours at 1,000uS but it was lowered 500uS as
this was closer to the community's average and it saved several hundred
pounds of salt a year.

In addition to the seachem buffer you may want to experiment with using
Sodium bicarbonate.  The seachem most likely has some carbonate buffers
but it also has chloride salts that will not help buffer but will increase
the conductivity.  A mix of the two may get you closer to your target

I use a simplified artificial saltwater mix dosed with a conductivity
controller to keep the systems at 500uS.  RO is added directly to the
sumps and salt is added by the dosing pump as needed.  To control the pH a
I use a fluidized aragonite sand bed.  This has a strong effect on pH with
only a slight influence on conductivity.  I keep our systems in the 7.2 to
7.6 range using fluidized aragonite.

I prefer the oolitic sugar sand by Caribbsea.  One to two liters of
fluidized sand keeps ~10,000 gallons in range.  I increase or decrease the
flow through the reactor as needed.  I've attached two images of reactors.
The large unit is in use and the small one is a prototype that can be hung
on the side of a Ahab or Aquaneering bench top or full rack filtration
unit. It is best to operate aragonite reactors with filtered water.

Please feel free to call me if you'd like to discuss this further.

Best Fishes
David Lains <}}}><
Research Assistant
Zebrafish International Resource Center
5274 University of Oregon
Eugene, Or 97403

Email: david AT zfin DOT org
pH: (541) 346-6028 ext. 18
fax: (541) 346-6151

-----Original Message-----
From: owner-zbrafish at [mailto:owner-zbrafish at]
On Behalf Of kayanemb
Sent: Thursday, May 12, 2005 5:51 AM
To: zbrafish at
Subject: Maintaining conditioned water.


Hello everyone. I'm having trouble maintaining the pH and conductivity of
our system water. We are trying to achieve a pH of 6.8-7.5 as well as a
conductivity of 200 - 400 uS. However, the pH is approaching below 6.6 and
whenever we add Neutral Regulator by Seachem to correct the pH the
conductivity goes up, and it is now at 900uS. Would anyone have any
suggestions on how to correct this problem.

Thank you

Kelly Nembhard


More information about the Zbrafish mailing list