| Feather Duster
Join Date: Nov 2003 Location: Duluth, Minnesota Age: 60
Posts: 249
Karma: 40
 
|  Re: anyone have problems with Crushed Coral substr
I didn't read all the posts, so bear with me.
First, I saw these some where;
Newie don't put air into the power head that is in the main tank. Not good for the fish.
It has no effect on fish and will actually/may increase the pH has it drives off the CO2 and increase the O2. I think someone is thinkin' on the lines of "gas bubble disease". You will not find this in a seawater aquarium. The disease is cause by N2 gas getting into the tissues, and the solubility of N2 gas in seawater is very low. Second, there is no difference between this and a venturi skimmer. The powerhead is using venturi action to pull in outside air, just like a venturi skimmer. Gas bubble disease is usually caused by pumps going through excess cavitation
That was the reason I asked you to aerate some water over night and then test the PH. *If I am correct then the water ( now fully saturated with Oxygen ) should have a lower PH
O2 has nothing to do with pH at all, be it night or day. The pH will be higher not lower, as you will drive of the CO2
and
Measuring the PH of suitably aerated water is a simple way of checking the oxygen saturation levels in the water. *My initial thoughts were that the O2 levels were being reduced at night and causing the PH to change which in turn was consuming the Alkalinity which allowed the Calcium levels to be so high ( phew ) *
O2 levels are being reduced at night because the plants are consuming O2 at night and giving it off during the day. The reason behind the low pH at night is because the plants are giving off CO2 and not using it for photosynthesi, as they are during the day. Increased CO2 drives the pH down. Alk has absolutely no effect on CO2 and CO2 has no effect on Alk. If the CO2 increases or decreases there is no change in the CO2. If the Alk goes up or down the same thing. However, when you ***add a buffer***, like Baking Soda, *its reactions generate CO2. *For each equivalent of Baking Soda there will be a 1 equivalent increase in the Alk and 1 equivalent increase in the CO2 concentration. If it was Washing Soda there will be a 1 equivalent change in the CO2 but a 2 equivalent change in the Alk, as Washing Soda is a double negated ion, CO3 -- . HCO3, form the Baking Soda, is a single negated ion HCO3- thus CO3 -- is twice *powerful / say, just like Sulfuric Acid is twice as powerful and Hydrochloric Acid. H2SO4 vs. HCl. The sulfuric has 2 H+ instead of 1H+
also
One can drive more carbon dioxide into the water through better aeration.
Nope, you will drive more O2 into the water and drive of the CO2 through aeration. The only real exception is if you have high room air CO2 or a somewhat pressurized reactor
I don't know what his problem is but after a year, if his readings are real, something is wrong. It could be the substrate is leaching out organics and lowering the pH around the media, dissolving it and increasing the pH Alk and Ca, just like a Ca Reactor. If the tank has a low Ca *demand the Ca and Alk will reach a peak and then stop. I just answered some question on our chem forum on CC media and how it can change levels, usually lowering the pH down to 7.8
Randy
Calcium carbonate will dissolve as the pH is lowered to the mid 7's and lower, and low pH often exists in sand beds where the oxidiation of buried organics can reduce the pH. That is not usually enough to sustain a reef aquarium, but if the demand is low, of the amount of organics entering the sand is high, or both, perhaps it can for a while.
Also, low alkalinity will encourage CaCO3 to dissolve. Have you measured the alkalinity in both aquaria?
Finally, there may be an initial stage where magnesium (from the salt mix) is replacing calcium in the surface regions of the substrate, and that may temporarily raise claicum.
and Boomer
Lowered the pH of the test tank........hang on a second I'll go get the report to be sure *Ok, I'm, back
SeaScope Vol 3., Spring 1986
Effects of Filter Material on pH, by Tom Frakes and Ed Mowka, Jr.
NO BIOLOAD
Crushed Coral = 7.94
Bahaman Coral Sand =8.00
Dolomitic Limestone = 8..22
Philippine Coral Sand =8.24
Puka Shells = 8.32
Quartz Gravel = 8.37
Control 8.27
Initial pH was 8.44, results after 3 weeks, using IO salt mix
However, even though Oysters are not in the table they are given in the text, dropping to 7.85, but this was more than 3 weeks. The only calcareous material that held good was Puka Shells. Another part of this study was over 90 days, with tanks that had a normal bioload. They dropped even more, with the silica sand going down to a pH of 7. Most of the calcareous materials didn't go below 7.75. Some of us have known for some time that Puka Shells are the best, as far as keeping the pH more normal than other materials but this too will stop after 90 days or so when dealing with a bioload
Also
Regarding initial PH, decreases reported here have been confirmed by many hobbyists and shop owners who consistently encounter pH levels of 7.8-8.0 in new aquariums using coral materials
And all of this is only part of the complicated story. There is what is called "surface-poisons" or "surface overgrowths, where at normal pH, Alk and salinity Hi-Mg Calcites precip onto the material. How much and how soluble it becomes later is base on the material and its composition |
