Quote:
Originally Posted by lastlight
so loosely translated i should just go back to watching for increased growth in my chaeto and swap my gfo then?  |
yah I think that's as good a method as any. I'm not sure how many hobbyists have the set up to safely do a wash with hot 1:1 HCl. We also are only measuring orthophosphate with our tests, so a teeny weeny amount of the P moving through our systems.
Don't get me wrong, I think there's value in knowing your orthophosphate concentrations, as having a high concentration of dissolved orthophosphate is as problematic as having no detectable orthophosphate but luxuriant and uncontrolled growth of problem algae, but I think we have to take the results from those tests with a gigantic grain of (sea) salt. Hanna has given us the spectrophotometer necessary to view P down to the ppb range, but for consistently accurate results you also need the analytical lab procedures called for at that resolution. If we were being really picky about it, we'd also want to centrifuge our sample first to make sure there was no microscopic particulates in the solution, but I doubt many hobbyists are going to run out and pick up a $10,000 centrifuge any time soon (even though they're freaking awesome).
If you're changing your GFO with any regularity, your orthophosphate concentration is going to be low, but that doesn't mean that your system's total P load will be low, and P will still be moving through the biological systems in your tank in ways you'll never be able to test for as a hobbyist, so it's really only one component of the whole tank maintenance thing.