Calcium causing ion imbalance?
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Randy Holmes-Farley
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The precipitate is certainly a concern, but I don't think he has a correct understanding of what caused the precipitate. It certainly is not ionic imbalance unless the person ignored magnesium for a long time and it got very low. I'm not sure he even understands what an ionic imbalance is since he also says ICP won't detect it.
Precipitation of calcium carbonate is primarily driven by high pH and alkalinity, to a much smaller extent by elevated calcium. It is also encourage by low magnesium, low phosphate, and low organics, all of which get onto growing calcium carbonate surfaces and stop precipitation. It can also be encouraged by ionic iron, such as on or downstream of GFO.
When you first add sodium carbonate (soda ash) or calcium or sodium hydroxide, the local addition point is prime for precipitation (high pH and alk), and needs to be mixed in fast. That's why it is important to add slowly to a high flow/turbulent area, spread out doses and dilute the product, if needed.
Using sodium bicarbonate will lead to lower pH and less chance of precipitation. Ionic imbalances issues, however, are exactly identical to sodium carbonate and again, not the issue.
There are some ionic imbalance issues using just sodium bicarbonate/carbonate/hydroxide and calcium chloride. That's partly why my DIY directions have a third part that contains magnesium and sulfate.
Those issues are eliminated or reduced by using a two part that includes many ions (such as ESV-B-ionic) or if you add the Balling sodium chloride free salt mix (Part C) to provide the balance. Neither of those actions will alter the potential to precipitate calcium carbonate.
Precipitation of calcium carbonate is primarily driven by high pH and alkalinity, to a much smaller extent by elevated calcium. It is also encourage by low magnesium, low phosphate, and low organics, all of which get onto growing calcium carbonate surfaces and stop precipitation. It can also be encouraged by ionic iron, such as on or downstream of GFO.
When you first add sodium carbonate (soda ash) or calcium or sodium hydroxide, the local addition point is prime for precipitation (high pH and alk), and needs to be mixed in fast. That's why it is important to add slowly to a high flow/turbulent area, spread out doses and dilute the product, if needed.
Using sodium bicarbonate will lead to lower pH and less chance of precipitation. Ionic imbalances issues, however, are exactly identical to sodium carbonate and again, not the issue.
There are some ionic imbalance issues using just sodium bicarbonate/carbonate/hydroxide and calcium chloride. That's partly why my DIY directions have a third part that contains magnesium and sulfate.
Those issues are eliminated or reduced by using a two part that includes many ions (such as ESV-B-ionic) or if you add the Balling sodium chloride free salt mix (Part C) to provide the balance. Neither of those actions will alter the potential to precipitate calcium carbonate.
Randy Holmes-Farley
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Use of calcium chloride and sodium bicarbonate/carbonate, and the third part as directed (magnesium chloride/sulfate) will not cause an imbalance involving any of those ions, but will, over time, cause a decrease in ions such as potassium, fluoride, borate, etc, that are not in the DIY formulation (but are in other types of two parts or Balling). The reason that happens is that sodium/magnesium/chloride/sulfate will accumulat e and slowly increase the salinity. When you lower salinity back to normal, those all go to their normal levels, but ions not added, such as potassium, go down.
Water changes help with this, but may not be perfect.
Craig Bingman modelled this decades ago:
Simulating the Effect of Calcium Chloride and Sodium Bicarbonate Additions on Reef Systems
Additional Simulations: The Combined Effect Of Calcium Chloride
/Sodium Bicarbonate Additions And Water Exchanges
Randy Holmes-Farley
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You're welcome.
Happy Reefing.
Happy Reefing.
