Hiya
glad i could help.
To expand on this slightly, and pointing to your tank, if your tank has been running for a year and the parameters are spot on then really you should be looking at a maximum of once a month, but i appreciate this takes a lot of trust in your system to take such a step. So in this case, do as you say, swap to bi weekly I suggest maybe for two months and then for sure swap to monthly, this will give you the opportunity to see how your tank reacts and also your tank bio rythm a chance to adjust.
Always remember you are playing with nature, no mater how smaller portion of nature that may be, but what ever size, nature hates change.
Hope that makes some sort of sense this time of night
best wishes
Michael
www.aqua-digital.com