Cdsdave said:
Okay, so I've raised the KH to 7 but my GH is still low at 3-4. I used baking soda to raise the KH. I have a bag of oyster shells in my spillway ( approx 3-5 lb). It's been there for 3 days and the GH hasn't changed. My pond is 2000 gall. 1) Should I add more shells or give it more time or both? Thanks guys.
PS Crsublette, thanks for that link. It was a good article and gave me the baking soda answer!
You're welcome. No problem man. :beerchug:
I would have given a more precise answer, but, generally, when folk don't know how to adjust KH, then there is much more to be learned and I think that hyperlink, and referenced hyperlinks within, covers quite a bit. So, rather than repeating myself, I just reference that thread most often. Glad it helped ya.
1) Should I add more shells or give it more time or both?
Give it time. Calcium carbonate products such as various formations of aragonite, crushed coral, lime, lithiqua, and other like products are very slow to dissolve. If you can get the product in a finer particle size such as in a sand formation or a powder, then it will react faster since there is more product surface area for more water to interact with the material.
Calcium carbonate requires an acid, such as carbonic acid and nitric acid and these occur naturally in the water, to break the bond between the calcium (Ca++) and carbonate (CO32-). There are always various acids naturally produced in the water, but nitric acid and carbonic acid are very common and I am guessing to be the most dominant. These acids are formed due to a hydrogen cation (H+) being added to the water or formed as the result of a material dissolving into the water. Carbonic acid (H2CO3) is a weak acid formed when carbon dioxide (CO2) dissolves into water (H2O) and carbon dioxide is constantly released into the water by algae, other aquatic plants, fish respiration, and when nature releases an hydroxide (OH-) into the water from anaerobic bacteria and organic decomposition. Nitric acid (HNO3) is a weak acid formed as a byproduct of bacteria progressing through the nitrification cycle.
Everything is in equilibrium in the water and the concentration ratios change according to many variables especially due to a change in pH. As the pH of water increases, then the concentration of carbonic acid is reduced. To get a better idea of the pattern I am talking about, then google "freshwater carbonate speciation diaghram"; the pattern changes according to many variables, but this will give you a visual sense of what is happening here. To help understand further this diaghram, this type of diaghram is called a
Bjerrum plot.
As the KH increases when using baking soda, then your pH increases to closer match the natural pH of bicarbonate, which is around 8.3~8.5, that is since you are using baking soda, which is sodium bicarbonate (NaHCO3). No matter how much baking soda you dose, the pH will never raise above 8.3~8.5 due to the baking soda. The pH will only increase above 8.3~8.5 whenever natural processes creating hydroxides, or removing a hydrogen cation, cause carbonate to form and to accumulate, but, if there is proper volume of calcium (Ca++) present, then this carbonate (CO32-) is precipitated, that is forming calcium carbonate (CaCO3). In other words, as the pH increases, nature actually will create a calcium carbonate product, rather than dissolve it.
So, now, you can see how everything comes into full circle and better understand why calcium carbonate becomes more and less effective.
Once the pH gets closer to 8.3~8.5, then the calcium carbonate does not dissolve as fast. Once the pH reaches 8.3~8.5, then the calcium carbonate
almost stops dissolving all together since there is very little acid present in the water, but the very low levels of nitric acid will still dissolve some of the calcium carbonate product.
If you can get a calcium carbonate product that has finer particles or pulverize it yourself, then the better it will dissolve at higher pHs, but it will still be slower as compared to it dissolving in lower pHs.
So, give it time for the product to dissolve and just keep in mind, that as the KH increases, the product will be less soluble.
Calcium carbonate products are more used to be a
stabilizer type product for calcium (GH) and KH rather than a product to act as an instantaneous injection. Baking soda is very near to being almost an instantaneous injection to increase the KH.
Calcium chloride, no additives, is very near to being an almost instantaneous injection to increase the calcium, which increases your GH rating. These "instantaneous injections" still take time to equilibriate in the water, but they are tremendously faster to dissolve than the calcium carbonate products, such as oyster shells, coral, etc. However, just as with most fasting acting dissolvents, do not add these two "instantaneous injection" products together; otherwise, they will neutralize each other by quickly forming a pure calcium carbonate product, which as explained above takes longer to dissolve. Wait around 12~24 hours between each fast acting product and first seperately dissolve the products in a seperate buckets, especially the calcium chloride since it can generate a fair amount of heat as it dissolves in water.
Of course, calcium carbonate products, such as oyster shells, coral, and lithaqua (which is formed from calcifying algae), has all sorts of other additional beneficial trace minerals in them, that can help your bio-filter and plants in the pond and fish. So, these particular products are adding more than calcium carbonate, which helps to make your pond more healthy.
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