[cobra]

Hey Folks,

Can anybody shed some light on our most common fertilizers (e.g., K, Mg, Ca, etc.) and the role they play with respect to osmoregulation?

IOTWs, what additive is most effective in reducing the stress (gradient) on the gill system's ability (chloride cells) to osmoregulate going from semi-hard water to very soft water?

My understanding is that some elements/compounds in water assist in the process more so than others and there isn't a lot of laymen's information when it comes to the Google (that I can find anyway).

Thanks!
G

 

[jmach]

Hey there. I just joined the forum again after a few years away from the hobby, so happy to get my tanks up and running again. I have not specifically studied fish physiology so my answer will be based on my current knowledge of osmoregulation.

Any amount of salts in the water (in this case salts refers to any ionicly bonded molecules within the aquarium, including our good old Na+-Cl). Very simply put, this attraction of charges forms this weak ionic bond that is what we refer to as salts. Any amount of salts within the water will result in a more hypertonic solution than water alone. This causes less water to enter the cells, and more water to leave to achieve equilibrium concentrations within and outside of the cell. In other words, a cell put within a hypertonic solution will "shrink" (crenate) and lose water. Generally, we would not find more or less stress in aquatic animals depending on these concentrations given standard aquarium keeping conditions. Most animals are decently adaptive to changing conditions, so unless you're planning on keeping a freshwater fish in seawater, you should have no trouble with slow acclamations to changing water conditions.

 

[cobra]

Hey there. I just joined the forum again after a few years away from the hobby, so happy to get my tanks up and running again. I have not specifically studied fish physiology so my answer will be based on my current knowledge of osmoregulation.

Any amount of salts in the water (in this case salts refers to any ionicly bonded molecules within the aquarium, including our good old Na+-Cl). Very simply put, this attraction of charges forms this weak ionic bond that is what we refer to as salts. Any amount of salts within the water will result in a more hypertonic solution than water alone. This causes less water to enter the cells, and more water to leave to achieve equilibrium concentrations within and outside of the cell. In other words, a cell put within a hypertonic solution will "shrink" (crenate) and lose water. Generally, we would not find more or less stress in aquatic animals depending on these concentrations given standard aquarium keeping conditions. Most animals are decently adaptive to changing conditions, so unless you're planning on keeping a freshwater fish in seawater, you should have no trouble with slow acclamations to changing water conditions.

Hi JMACH,

There's plenty of talk on the web about isotonic conditions, hypotonic conditions, and hypertonic conditions as it pertains to osmotic regulation. But, little talk about the the typical fertilizers (salts many of them) that we use in our aquariums and how some may help or hinder the osmotic process. I'm not talking about overall hardness or softness of water, but rather the constituent parts that make up the hardness and how some have a greater effects on the hardness (or softness) of the water itself and subsequently osmoregulation.

What got me thinking about this is there are some threads on apistogramma.com that delves into greater detail about water hardness, TDS, conductivity, etc., when it comes to fish keeping and acclimation.

I think it can be fairly easily argued that most people encounter softer to harder water conditions in terms of collecting (buying) fish and introducing the stock to their aquarium. I have the opposite issue: most fish that I collect are from hard or basic waters and I have to introduce them to water that is very soft with a low pH. Surprisingly, I run across a lot of breeders who know very little about the nature of the water they raise their fish in. Usually, they can only quote me temperature and pH. More often than not they know very little about the TDS, conductivity, and why their water is hard or soft to the degree that it is.

Here are a couple of the threads that got me thinking about all this more in depth:

Maximum pH delta with drip acclimation | Apistogramma.com

and this:

TDS vs hardness | Apistogramma.com

 

[jmach]

I have yet to see any solid researched information on how TDS and KH and GH relate, but from my experience and calculations TDS= KH (carbonate) + GH (mostly Ca and Mg) + other molecules in the water. For your sake, it sounds like a slow drip acclimation would be fine for your fish. You don't have to worry as much about pH shock as some people will lead you to believe (keep in mind our blood can vary in pH as low as 5 around our stomach after we have had a big meal!)

-Jared