Hi twinki, what I meant by "monthly cycle" was that once you have fish, the clock begins ticking for not only your weekly gravel-clean-water-change maintenance but also your regular filter maintenance. When you are first starting off, there's no way to know yet what would be a good interval of time (what I was calling "cycle") between filter cleans. I like to recommend just starting with once a month, but testing and logging in your aquarium notebook so that you can modify that interval to be shorter (eg. two weeks) or longer (eg. 6 weeks) depending on several factors.
The main feedback test for overall maintenance is the regular nitrate(NO3) reading. Your liquid nitrate test will be more reliable in its readings after the fishless cycle is over and all the nitrite(NO2) that tended to throw it off is gone. It will take weeks of feedback but basically what you're hoping it will do is settle down such that the water changes and filter cleans you are doing will cause nitrate(NO3) to just "stay steady."
A good range we like is 15 to 20ppm -above- whatever your nitrate(NO3) level is. (So if you had 10ppm nitrate in your tap water, then 30ppm would perhaps be the upper number we'd like to see it holding steady at. But really its the "steady" and not rising that's important, not the absolute NO3 number that it stays steady at. Does that make sense?
Nitrate(NO3) is not really the only bad chemical we want our water changes to remove, it just happens to be one we can make a cheap test for and we can use it as a "surrogate" for what we think other unwanted chemicals are doing. There are hundreds of organic molecules and heavy metal type ions in our tank that we don't want to build up (it would build up if we were "topping up" rather than water changing! -- that is why "topping up" is not a good thing if we don't also do water changes.)
Likewise, we want to squeeze or swish out the biomedia in our filter on a regular basis so that it won't provide too large a repository for NO3 and other bad chemicals and so that it won't clog up mechanically due to too much debris. We want the filter to continue to flow nicely with the same flow rate as when new. We also want to clean the impeller and its area and re-lubricate all the seals, if the filter has any. So, based on whether we see too much clogging or whether the filter seems rediculously clean, we can consider modifying our "starter interval" of once a month! Does that make sense?
~~waterdrop~~
