This one threw me! Tank has been set up for about a year. Converted to planted tank about 6 months ago.
Substrate - Mix of inert gravel and Eco Complete
Med to Heavy planting
1 65w Coralife
DIY C02 (two 2l bottles)
N - 1/8 tsp 3x/week
P - ~ 1/32 tsp every two weeks
k - 1/16 tsp 3X/week
Micros - CSM+B 1/16tsp 3x/week (Flourish Iron 2ml 1-2x/week)
H20 changes - 50-60% week
Plant growth has been great but not out of control.
I use two different Nitrate test kits, both validated to be fairly accurate with reference solutions.
With my current dosing, Nitrates typically read between 10 and 20ppm. To my surprise, last night when I tested I got big zero's with both test kits. Checked the test kits against a ref solution and the kits are still reading accurate.
Last week when I cleaned the XP3, I added carbon (from Rena) to one of the baskets. I have run carbon before and it has never stripped the Nitrates out.
So this is what I believe impacted my Nitrate levels..
Two days ago I hooked up my Diatom filter. Was craving that waterless tank look.... I had read somewhere that a good way to clean the substrate in a heavily planted tank was to use a Diatom or other high flow filter while fanning the substrate to lift debris off the bottom. So, I ran the filter about 4 hours while periodically fanning under and around the plants. The Diatom sucked a lot of crud out of the water column. At the end of the four hours not much floated when I fanned the bottom. This was all done at the surface of the substrate. I was not disturbing the actual substrate layers.
So my questions....
1) Could my Diatom cleaning exercise have removed enough mulm to drop my nitrates to zero? Even Dosing 1/8tsp 3x week?
2) If this is the case, is this "unhealthy" to clean my tank this way on a regular basis, say monthly?
I imagine if I continue this practice, I may have to increase my KN03 dosing to account for the loss in nitrogen waste in the tank.