- Joined
- Sep 5, 2014
- Messages
- 66,553
- Reaction score
- 62,857
I'm not satisfied with this reasoning. If phosphate was indeed maintained at 0.00 (whatever that means, precision to that level is often below the detection limits), then adsorption would be very slow. My understanding is that it is an equilibrium process, much like GFO. There are some calculations in the thread Randy linked to, but in order for the sand to be a "smoking gun", I would think the tank would have had to have seen significantly elevated phosphate at some point prior. One possible exception would be greatly increased local phosphate concentrations in the sand bed, but I don't know enough about that to comment on it.
There are a lot of variables, though. Perhaps the sand was stirred accidentally, releasing nutrients into the water. Perhaps the bacterial population crashed. The list goes on.
I agree.