A couple issues have come up in recent posts to which I would like to respond.
On the pH...I will suspect it is actually 7.5 and not 6.8, since your GH and KH are apparently high. The reason it may test 6.8 initially is because of dissolved CO2 in the water line; this is very common. As the CO2 dissipates out, the carbonic acid it produced leaves and the pH rises to its actual level. Letting a glass of tap water sit for 24 hours and then testing pH will likely confirm this. So adding the tap water to the tank is not really going to shift the ph in the tank as the true pH of the tap water is likely going to be very close to the tank water pH.
On the temperature...is there some reason you do not use hot and col water at the tap, mixing it to get roughly the same temperature as the tank water? And it does not need to be exact; usually a couple degrees cooler can invigorate fish. I use my hand and always have the fresh water just a tad cooler than the existing tank water.
Water changes are absolutely essential for healthy fish. There is a lot of "pollution" in any aquarium with fish. We do not do tests to determine water changes, but rather doing substantial water changes stabilizes the biological system so we don't see fluctuations. Ammonia and nitrite should/must always be zero. Nitrates should be as low as possible, and this is where regular substantial water changes can really make a difference. But there is also all the other "crud" that no filter can remove. "Dead water" has to be removed and replaced with fresh. And the more you do, thee better, providing parameters (GH, pH and temp) are relatively close.
Inappropriate water parameters (GH primarily) do cause issues for fish. How far this can go on is debatable. The authorities do agree that it weakens the fish, which makes them more susceptible to other problems they encounter and to which they would otherwise have been able to deal with more effectively. And they live shorter than normal lifespans, always.
Fish in nature obviously do not die off from ich, and no one is out there "treating" ich. Stress is the real issue, as it causes 95% of all fish disease in an aquarium; the pathogen or whatever has to be present (many are) but it is the stress weakening the fishes' immune systems that triggers the outbreak of the disease. The harder the fish must work to maintain normal every-day functions takes a toll on them, causing stress.
If you decide to use RO and prepare your water in separate containers outside the aquarium, remember this is a permanent choice. It has to be done for each and every water change. It is easier to select fish suited to your water going forward.
Bacteria live on surfaces, and they are very difficult to dislodge. If you were able to scrape every grain of substrate you might remove some of them, but a vacuum during the water change is not going to have any effect. Same with rinsing out the filter media. Keep it all clean.
On the pH...I will suspect it is actually 7.5 and not 6.8, since your GH and KH are apparently high. The reason it may test 6.8 initially is because of dissolved CO2 in the water line; this is very common. As the CO2 dissipates out, the carbonic acid it produced leaves and the pH rises to its actual level. Letting a glass of tap water sit for 24 hours and then testing pH will likely confirm this. So adding the tap water to the tank is not really going to shift the ph in the tank as the true pH of the tap water is likely going to be very close to the tank water pH.
On the temperature...is there some reason you do not use hot and col water at the tap, mixing it to get roughly the same temperature as the tank water? And it does not need to be exact; usually a couple degrees cooler can invigorate fish. I use my hand and always have the fresh water just a tad cooler than the existing tank water.
Water changes are absolutely essential for healthy fish. There is a lot of "pollution" in any aquarium with fish. We do not do tests to determine water changes, but rather doing substantial water changes stabilizes the biological system so we don't see fluctuations. Ammonia and nitrite should/must always be zero. Nitrates should be as low as possible, and this is where regular substantial water changes can really make a difference. But there is also all the other "crud" that no filter can remove. "Dead water" has to be removed and replaced with fresh. And the more you do, thee better, providing parameters (GH, pH and temp) are relatively close.
Inappropriate water parameters (GH primarily) do cause issues for fish. How far this can go on is debatable. The authorities do agree that it weakens the fish, which makes them more susceptible to other problems they encounter and to which they would otherwise have been able to deal with more effectively. And they live shorter than normal lifespans, always.
Fish in nature obviously do not die off from ich, and no one is out there "treating" ich. Stress is the real issue, as it causes 95% of all fish disease in an aquarium; the pathogen or whatever has to be present (many are) but it is the stress weakening the fishes' immune systems that triggers the outbreak of the disease. The harder the fish must work to maintain normal every-day functions takes a toll on them, causing stress.
If you decide to use RO and prepare your water in separate containers outside the aquarium, remember this is a permanent choice. It has to be done for each and every water change. It is easier to select fish suited to your water going forward.
Bacteria live on surfaces, and they are very difficult to dislodge. If you were able to scrape every grain of substrate you might remove some of them, but a vacuum during the water change is not going to have any effect. Same with rinsing out the filter media. Keep it all clean.
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