Quote:
Originally Posted by FragIt Dan
Just keep increasing your dose until it starts to climb. I ended dosing 10x the base recommendation in order to keep up. Sounds like you have to do the same. When your corals eventually get healthy again expect to increase your dose again as they start to grow. For comparison, I am dosing about 25g anhydrous CaCl/day into a 90G heavily stocked with sps. You can look up the reef calculators to compare that with your dosing. Quick solution ... double your dose every day and test every day until you see it rise.
Dan
|
Unless he's resolved his sky high alkalinity and pH issues, doubling up on the rate he adds calcium is just going to cause calcium carbonate to precipitate out all over everything.
Quote:
Originally Posted by ashr
My Calc level is still under 300.. I really need to do something before i lose more SPS. 
Anything with polyps on the out side ( fuzzy ) are just peeling off. pretty sad to see |
Have you been able to get your alk and pH down? Losing corals might also be related to those parameters.
I'm not sure what your current parameters are, but it's really important to understand a little bit of the chemistry that's occurring in your water. It's not as simple as simply 'calcium low, add calcium', or 'alk low, add baking soda' if you've been dosing these chemicals at a significantly unfavourable ratio for any period of time, which a malfunctioning doser can do easily. Things like ion saturation, pH, and the ratio of carbonate to bicarbonate in your water (which is very strongly linked to pH), and the solubility of calcium carbonate all determine whether the extra calcium you put in will change the levels you see in your water, or simply end up as a film of calcium carbonate slowly eating away at your pumps. Remember, while calcium is a 'thing' that you measure directly, alkalinity is not a 'thing' in and of itself. It is a measurement of the cumulative interactions of a series of other, complex things, of which carbonate and bicarbonate play a major, but not exclusive role.
There's a really good primer on this in reefkeeping magazine:
http://reefkeeping.com/issues/2006-06/rhf/index.php
Important points from that article:
1. When you dissolve 'alk' solutions, you're dissolving either sodium carbonate or sodium bicarbonate in most cases. However, once either of those compounds are dissolved, the carbonate part will become bicarbonate, or the bicarbonate will become carbonate based on a whole bunch of complicated reactions and conditions, but the most important of which being the pH of your water. Regardless of what you've been adding to your water (sodium carbonate or sodium bicarbonate), the major part of your 'alkalinity' will always be made up of a ratio of carbonate and bicarbonate ions, as they can pick up or drop the hydrogen ion pretty easily in solution.
2. The higher the pH, the more carbonate vs bicarbonate you will have in your water. At the pH you listed in your opening comment, your water will favour carbonate over bicarbonate to the extreme.
3. Calcium carbonate is MUCH less soluble in water at a higher pH. This is because carbonate is so favoured at higher pH's (vs bicarbonate), so calcium ions are way more likely to 'bump' in to carbonate and react. Simply driving the pH of a tank up can be enough to drop your calcium and alkalinity concentrations through the floor, regardless of any process that's occurring.
4. Calcium and carbonate ions are always entering and leaving solution, regardless of if you're adding supplementation or not. At equilibrium in an unsaturated solution, the rate at which they react, form a solid, then dissolve again is equivalent, meaning you'll never get a precipitation. However, like with pH, the solubility of calcium carbonate is also tied to the alkalinity of your tank (partly due to the fact that alk and pH are related, but alkalinity is more complicated than that). Calcium carbonate is less soluble at higher alkalinities, which means that at higher levels of alkalinity, the amount of calcium that can be kept in solution is lower. To quote reef keeping:
"Lower calcium carbonate solubility at higher alkalinity implies that precipitation of calcium carbonate can be more extensive. In other words, as the alkalinity rises, the amount of calcium that can be kept in solution without precipitation decreases.
This effect is why, for example, maintaining a very high alkalinity can lead to excessive precipitation of calcium carbonate onto objects such as heaters and pumps. Likewise, as the alkalinity is reduced, the amount of calcium that can be kept in solution without precipitation is increased."
The gist is, if your alkalinity and pH are both still really high, you can add calcium until the cows come home, but you won't start seeing the levels of calcium in solution rise until the addition has caused so much calcium carbonate to precipitate out of solution that you're alk and pH both start to fall. In the process however, you will have shaved years off the life of your powerheads, return pump, and heaters, if not caused them to fail already.
You need to get pH and alk down to 'normal' levels before you start messing with calcium. The easiest, safest, and fastest way to do that is through a series of water changes with a properly balanced salt mix.