High Alk and Fish

[treehugger]

hello Lee-
A question was posed to me the other day and I wasn't quite sure of an answer and couldn't find any specifics. The question "What effects if any would an abnormally high Alk have on fish and how high would the alk have to be before visible signs of distress (if any) would be seen?" In order to get abnormally high Alk levels there would be other elements out of balance most likely Ca/Mg but at what point to things become problematic or fatal? I would like to mention this is not a reef situation but rather a theoretical fish only system. Any and all thoughts would be welcome.
Thanks
Jeff

 

[leebca]

You'll get some information about your question in this post: What is Water Quality.

What our fish (desperately, for the most part) need is a stable pH environment. The balance of Alk, Ca, and Mg is what buffers the water and maintains pH stability. Check the chart in the above post.

When any of these three move out of alignment, the pH moves to the wrong area and/or is no longer stable (fluctuates). Marine ornamental fishes don't handle changes in pH very well, at all. I sigh when I get posts about not being able to control pH or make it go to a specific place, when in reality, pH is controlled by the balance of these three.

There is little outward appearance of these kinds of fish stressors to the hobbyist. Most chronic stressors cause little visual change to the fish and are invisible to our eye. However, the fish becomes susceptible to other maladies, opportunistic microbes, and has a shortened lifespan. These kinds of stressors do cause internal (physiological) problems, some of which are found in the blood.

Because of these 'unseen' results, many hobbyists ignore these stressors thinking 'all is well' but their fish are surviving, not thriving.

 

[treehugger]

Thank you for your reply. I read that sticky before I posted. I know that pH swings can cause some serious problems. With high Alk, would pH test higher then normal but be likely to fluctuate and have more volitility? I guess my biggest question though, is what types of outward physical distresses/damage would show first and what would be observable to the hobbyist. If you were to allow your water parameters to get out of balance to the extremes I mentioned above, what types of lasting damage would it do to the fish that survived this initial problem? Would there be liver or kidney damage do to osmoregulation and if so what types of observable distress or damage would a hobbyist see? Thanks for your time. I really appreciate it.

 

[leebca]

I'm sorry, I thought I was clear. The outward signs would be opportunistic microbial attack, susceptibility to other maladies, and a shortened lifespan.

It takes energy from the fish to maintain its internal physiology. When the exterior condition require the fish to correct or resist those conditions, energy is consumed. This energy is used to fight off opportunistic microbes/pathogens, repair of fish (external and internal). There will be no other visible signs from an Alkalinity extreme.

Blood work will show it up quickly.

Since these sorts of conditions are not imposed upon our ornamental fishes, there is no definitive knowledge about what internal effects would show up, let alone if they could be attributed to just an Alkalinity extreme.

Part of the answer to your question is in that post:

As the hobbyist chooses the higher alkalinity concentrations from the above table, the pH generally goes down to accommodate keeping the would-be precipitate of carbonates in its dissolved state.

The high alkalinity without proper balance will drive the pH down until the carbonates cannot any longer stay dissolved. This is the 'milky water' state some hobbyists see when they fail to test properly and/or keep things in balance. You can raise the alkalinity just so far.