alright...i hav had the filter in my tank for about a day and the pH has returned to 7 (the origonal water). im guessing since when i pulled the filter out it looked like a light coffe inside so im guessing it collected the nutrients by adding one n two together. the fact that it was pH 7 and pretty clear was more than enough evidence for me. for anyone who had my same question, i personaly don't recomend a water filter in your res. I thought a filter would clean the water of the hydroton dust that is settles but the best thing to do is just try and your system dirt n dust free.