Ok I think we are on the right track now for the most part as for the relationship between pH and kH, as well as it's role in nitrification. Now we can discuss why possibly a bead filter would require a higher kh to function properly. I know of no science that can explain this or if it is truly the case the case at all. I think most folks reading thru this thread should understand the basics now. It seems that no one can come up with any science that would suggest a bead filter needs a different set of kH values as compared to any other bio filter. I am not saying this is impossible, I just need a starting point of science to be able to come up with any theories of my own. Is it bead filters or is it just any pressurized filter that we are talking about? Once again I know of no science that suggests a bead filter needs a different set of parameters as compared to other types of biofilters to function properly. With the dozen bead filters I have in operation I have never noticed a difference in their function as compared to other biofilter types which I also run. About half of my bead filters are used as the sole biological filtration for heavy fish loads, and the other half are used in conjunction with other types of biofiltration as well. In the latter case the bead filters are not primarily for nitrification but more for polishing the water in my retail tanks.
So, as for the question of the possibility of a bead filter needing a higher kH, could it be the pressurized part of all this that could possibly matter? I don't think so but invite anyone to show me some science on this particular subject, and that the problem exists at all. Until then, and with the information discussed by all in this thread I think we have come to the conclusion that a bead filter does not require a different kH than other filters as for the nitrification process in general. With that said find your own personal levels of kH that keep your pH stable and your nitrification working at its optimal capacity, no matter what type of biofilter you may have. IMHO that range will vary and be between 80 ppm minimally
if you are one that add BS as a buffer to maintain kH and as for the maximum I know of no reason to keep it above 200 ppm, other than if you only wanted to have to add more buffers because of kH depletion once every six months or more. Otherwise I would go out on a limb and say most folks that buffer with BS should maintain a range from 80ppm to a max of 175 (or 200 if it makes you feel better.) You can easily find all of this out for yourself if you have a bead filter and buffer with baking soda. Peace out