Overnight rise of pH in new tank
I set up the new 38 gallon tank (with new gravel), filled it half full with water from my tap (well water with a pH of 6.0), and started the Fluval 305 and heater, left it overnight. The next day, I checked the pH of the water and it had risen to about 7.
I set up the new 38 gallon tank (with new gravel), filled it half full with water from my tap (well water with a pH of 6.0), and started the Fluval 305 and heater, left it overnight. The next day, I checked the pH of the water and it had risen to about 7.
I really haven't ever come up against as dramatic a rise in the pH as you describe, the water seems to be buffered up in some way, and generally I would never blame that on carbon. Carbon has been blamed for a number of things, but pH rises in such dramatic fashion are not one I have heard. So.... the next question is what could be causing the problem. The only other lead you give me is the addition of new gravel. Now I know that gravel is supposed to be inert, but there are so many types and colors that the composition of the gravel actually could contribute to the rise. I am unaware of the brand or gravel type called Colorado River so I must assume it is not one of ours. But, I will tell you that some of the substrates used for gravel include dolomite (the white gravel) and are often marked that the gravel should only be used for African Cichlid tanks since it will buffer pH alkalinity and raise the pH over time. Other gravels may have a number of impurities and non-inert compounds that epoxy often covers and eliminates, but this might be the source of the problem. So you can see, if the actual gravel is not inert (and it may not be right in the beginning) and the epoxy coating is somewhat compromised the pH could rise a little - but your rises are way too dramatic for even this explanation. So now we have to look into the filter as well, did you use anything other than carbon, foam and BioMAX? None of these would cause the problem in any noticeable degree. The only other thing I can suggest is to draw some water from your tap and let it stand in a clean glass container overnight. There should be no soap, and the container must be well rinsed in clear water to ensure it is very clean and not contaminated. After it has stood for a day or so, then test on the actual tap water to see if the pH from the tap changes. I have also heard of that being the case where the buffers in the water are so minimal that water pH will rise without the addition of media or other things at all. To be even more sure, aerate a second container to see if added oxygen (or simple water movement) will cause organics or diffusable acids to be removed by contact with the atmosphere, raising the pH automatically. Anyway, at the present I am baffled as to the rise, it is not usually the case with any filter. And you are not using all that much more carbon with the Fluval if you remember that you are also filtering a lot more water so the argument of so much more carbon is a bit misleading.
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