RE: NANFA-- weird darter illness?

Crail, Todd (
Mon, 13 Jan 2003 08:40:23 -0500

That's not any fun Geoff. :(

A few other scenarios:
- If the pump is an external pump and "hard plumbed in" from a sump, holes in
the line can act as air injectors without dripping any water.
- Loose seals on flex line from a pump in a sump can inject air. For example,
a return pump with 3/4" flex hose to some type of return valve. Canister
filters are sometimes guilty of this.
- Gaps inside an external pump can cause a situation called "cavitation" where
little pockets of air form in the propellor chamber and cut up into fine fine
fine bubbles.

Before we think about this much more, what is your filter/pumps setup like?
And if it is on a sump or using a canister filter, are you seeing micro
bubbles, or big blobs of air come out of the return (The whirlpool Nick
mentioned is a classic indicator)? Once we know how the lines are setup, it
will be easier to see what action may be necessary. :)


-----Original Message-----
From: Nick Zarlinga
Sent: Monday, January 13, 2003 7:51 AM
Subject: RE: NANFA-- weird darter illness?

Sounds like you might have some kind of supersaturation of gasses happening
in your system. Any chance you have a pump on the system which is sucking
air through the intake? What happens in a situation like this is that the
air that gets entrailed in the intake of the pump gets "sucked" so hard that
it essentially gets dissolved into solution. This is especially prevelant
if there is some kind of pressure chamber after the pump, such as an ocean
clear filter or the like. The air that gets dissolved in the water passes
through the fishes gills and collects in the capillaries of the fish.
Usually it is most noticable in the fins but I have had it happen on the
skin at times also. Essentially, this is the same effect that SCUBA divers
get when they get the bends. It is the nitrogen that is actually the
culprit which comes out of solution (blood in this case). Sort of like
opening a pop can and having it effervesce. It is also more dangerous in
cold water than warm since cold water can hold more gasses. To alleviate
the problem, check all the intake lines of the pump and make sure that there
is no "whirlpool" effect and that all connections are secure. Also, never,
never, never...... have your effluent from a pump enter the tank under the
surface of the water. You need to have some surface aggitation to degas the
water. It is also good to run the water through a degassing chamber, such as
a trickle filter.

Nick Zarlinga
Aquarium Biologist
Cleveland Metroparks Zoo
216.661.6500 ext 4485
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