I know TDS stands for total dissolved solids, but what exactly does that mean? And how would TDS fluctuate and harm fish?
What are TDS?
- Thread starter Industrial
- Start date
Basically every dissolved material...including calcium, magnesium, phosphates, nitrates, potassium, chlorides, sodium, bicarbonates, etc.
Osmoregulation helps to keep the osmotic pressure of the fish's fluids in balance ie. homeostatic. Fish are actively trying to maintain a standard salt concentration with their bodies (see pic below). Since freshwater is generally low in salts, fish are adapted to dilute their urine by expelling large amounts of water. Concentrations inside and outside cells want to reach equilibrium thus water normally flows into the fish, from the low salt concentration to the high salt concentration, and would otherwise cause cells to swell and potentially burst without regulation. Valuable salts also will diffuse out through the gills in effort to balance concentrations. This entire process takes energy which is why sudden changes in TDS will stress out the fish.
Osmoregulation helps to keep the osmotic pressure of the fish's fluids in balance ie. homeostatic. Fish are actively trying to maintain a standard salt concentration with their bodies (see pic below). Since freshwater is generally low in salts, fish are adapted to dilute their urine by expelling large amounts of water. Concentrations inside and outside cells want to reach equilibrium thus water normally flows into the fish, from the low salt concentration to the high salt concentration, and would otherwise cause cells to swell and potentially burst without regulation. Valuable salts also will diffuse out through the gills in effort to balance concentrations. This entire process takes energy which is why sudden changes in TDS will stress out the fish.
Bah...I can barely understand what I am saying myself, I apologize.
Anyways, here are some decent reads to at least get the gist of what is going on...
http://www.angelsplus.com/ArticleOsmosis.htm
http://www.cartage.org.lb/en/themes...lphysiology/osmoregulation/osmoregulation.htm
Anyways, here are some decent reads to at least get the gist of what is going on...
http://www.angelsplus.com/ArticleOsmosis.htm
http://www.cartage.org.lb/en/themes...lphysiology/osmoregulation/osmoregulation.htm
Thanks for the info, but to me it sounds more like a discussion on salinity. Is TDS like salinity?
TDS is a general measure of Everything thats dissolved in the water. Salt, hardness, nitrate etc. So it could be made up of different elements.
But it you start with distilled water, it has zero dissolved solids. As stuff gets added, the TDS increases. But you don't know what those elements are just from the TDS value. Maybe your water is hard, maybe it's a slightly brackish tank, maybe you need to do a water change?
Ian
Here's another great TDS article posted on the plecoplanet forums.
http://www.plecoplanet.com/forum/showthread.php?t=3480
http://www.plecoplanet.com/forum/showthread.php?t=3480