11-11-2010, 03:53 PM
| || |
Natural wood will lower pH as it releases tannins, but this is slow and unless you have a considerable number of chunks of wood it is unlikely to lower the pH by more than a few percentage points, say from 8.2 to 8 or maybe 7.8--but even this can be unlikely if something else is working opposite to increase the hardness--such as seashells that are increasing hardness and corresponding pH. The wood will last quite a while, but eventually it will rot and fall apart, though depending upon the wood that may take years.
Peat works the same, but much faster so it needs to be replenished regularly. This depends upon the hardness of the initial water; the harder it is, the more peat will be needed and the faster it will become exhausted and need replacement. I've never used peat, so I can't suggest how many, how often. First you should find out the hardness, GH (general hardness) and KH (carbonate hardness) as they are inter-related to pH. Your water supply people can tell you the hardness, and they may have a website with such information (what's in your water, useful information to know, it can surprise you). The higher the KH (carbonate hardness) the more it buffers the pH, preventing any lowering you might be attempting.
If you goal is to significantly soften the water and lower pH, I would consider a RO (reverse osmosis) unit; initially expensive, but long-term it pays for itself. This if you need/want softer water, and depending upon what extent.
Last comment: do not use salt in freshwater aquaria. I'll end with some information I prepared previously that will explain the effects of salt; as Betta are very soft acidic water fish, they have a suceptibility similar to characins.
Salt is detrimental to freshwater fish and plants in varying degrees. To understand why, we must understand what salt does in water.
Salt makes the water more dense than the same water without salt. The aquarium contains water. The bodies of fish and plant leaves also contain water [just as we do--we are, what is it, 70-some percent water?]. The water in the aquarium and the water in the fish/plant are separated by a semi-permeable layer which is the cell. Water can pass through this cell. When either body of water is more dense, the other less-dense body of water will pass through the membrane to equalize the water on both sides.
Water is constantly passing through the cells of fish by osmosis in an attempt to equate the water inside the fish (which is more dense) with the water in the aquarium. Put another way, the aquarium water is diluting the fish's body water until they are equal. Freshwater fish regularly excrete this water through respiration and urination. This is the issue behind pH differences as well as salt and other substances. It increases the fish's work--the kidney is used in the case of salt--which also increases the fish's stress in order to maintain their internal stability. Also, the fish tends to produce more mucus especially in the gills; the reason now seems to be due to the irritant property of salt--the fish is trying to get away from it.
I have an interesting measurement for fish. Dr. Stanley Weitzman, who is Emeritus Research Scientist at the Department of Ichthyology of the Smithsonian Institute in Washington and an acknowledged authority on characoid fishes, writes that 100 ppm of salt is the maximum for characins, and there are several species that show considerable stress leading to death at 60 ppm. 100 ppm is equal to .38 of one gram of salt per gallon of water. One level teaspoon holds six grams of salt, so 1 tsp of salt per gallon equates to more than 15 times the tolerable amount. Livebearers have a higher tolerance (mollies sometimes exist in brackish water) so the salt may be safe for them.
Plants: when salt is added to the aquarium water, the water inside the plant cells is less dense so it escapes through the cells. The result is that the plant literally dries out, and will wilt. I've so far been unable to find a measurement of how much salt will be detrimental to plants; all authorities I have found do note that some species are more sensitive than others, and all recommend no salt in planted aquaria.