Matt,
the superbuffer will initially raise your pH, as it contains sodium
carbonate in addition to the sodium
BIcarbonate. I still would suggest that you use the plain ole' baking soda, due to its relatively low cost and the absence of the sodium carbonate. The pKa of sodium carbonate is around 11.4, and as such will drive your pH to close to that level during the initial establishment of equilibrium while the carbonte/bicarbonte system re-estblishes itself in the presence of the new ion concentrations. At times, the increase in the pH of the tank water, even temporarily, can make the difference between having a precipatory snow event of calcium carbonate and having the ions stay in solution. As pH rises, solubility drops for these two ions (calcium as Ca++ and bicarbonate/carbonate as -HCO3 or --CO3 ions), especially in the presence of each other and a mild hypomagnesium state (Mg should be ~1300 PPM if the tank is at 80 degrees F and 35
PPT salinity). I assume the
Ma your refer to is for magnesium, which is signified by
Mg. If your Mg++ ion concentration is in the 1100's, your ASW has become skewed in terms of the actual percentages of each of the conservative elements necessary to maintain appropriate calcium and alkalinity in the water column. This usually only will occur in situations where calcium is added to maintain high calcium levels without adding any alkalinity, or situations where the salt has become wet (as witnessed by clumping in the dry ASW mix) and caused changes in the composition of the mix due to the formation of insoluble salts of the mixes reactive components (for example: calcium carbonate from calcium chloride and sodium bicarbonate, or calcium sulfate (gypsum) from calcium chloride and magnesium sulfate, etc.). These reactions not only result in insoluble precipitates forming in the bottom of the mixing container when dissolved, but also reduce the availability of these needed ions to distribute the solubility of the many ions that are near saturation when properly mixed to make ASW at 35 PPT. With such salt, no matter how many water changes you make, the results will pretty much be the same. This "wetting" of the salt mix occurs whenever the lid is left off the container for extended periods of time, as the mix is VERY hygroscopic, and will take moisture out of the air and begin to allow reactions of the now wet salt to occur. The fix is to get new salt, make your ASW, bring it to 35 PPT, check it again after 24 hours of heating and circulation, then make a large (>50%) water change in your system to help reestablish the proportionality of your conservative elements. This will need to be carefully matched for temp, salinity and pH when doing such a large water change (personally, I would recommend around 75% water change with the matched seawater).
Does your salt have clumps or a crust on it? Do you store it in a bag or in a "tight" container? This "wet" salt reaction may be your problem. However, unless you are adding other additives or using two part calcium and bicarb supplementation, I am pretty much at a loss. If you are using tap water (which in areas where the water is hard, has the same effect as adding unbalanced calcium and/or carbonate to the system), it COULD be your cause as well. It would be smart to test your water that you use to do your mixing for the ASW just to make sure even if you are using a filter for your system's water... Look for calcium or alkalinity in your top off or ASW mixing water.
So far, potential significant issues:
- high calcium
- low alkalinity
- low magnesium
- unknown temp and method of testing salinity
- unknown pH swing for 24 hr cycle
- possible skewed proportionality of ASW
- questionable salt mix quality
- potential salt storage issues
- unknown additive history
These are the things we need to either ascertain or address.
So if i raise my Alk the Ph will rise and my Calcium will fall ??
Back to the lfs i go
