Article by: Jeremy Linzmaier ( jlinzmaier )In my filtration article, I alluded to a thread on RC in which a few well known chemists (and others) were experimenting with the regeneration of GFO. I’ve researched and performed the process, so let me save you some time and sum up the process for you.
If there are any questions about this article please visit the Q & A thread HERE
To start with, stop throwing out your GFO when it's exhausted!!!
GFO (granular ferric oxide) is a substance which has a high affinity for phosphate due to its molecular make-up. The GFO can only adsorb a specific amount of phosphate (and other molecules) onto its surface before the entire surface and binding sites are filled. This molecular exhaustion can take days, weeks, or months depending on the tanks phosphate levels. The only way to know if your GFO is exhausted is to test for po4 with an accurate meter or (a more gross measurement) monitor for signs of increased algae growth.
GFO also creates localized pH changes in the water within its immediate vicinity which potentates the precipitation of caco3 onto its surface. This process blocks the po4 binding sites and exhausts the GFO faster. This is quite common and often noticed as the GFO begins to look milky or white instead of dark brown. Luckily that's an easy fix. Removing the bound po4 is a little trickier.
The process of dissolving the caco3 and removing bound po4 are both necessary for thorough GFO regeneration. They are very separate processes and should be carried out individually.
Let me add a disclaimer for the process I'll outline.The GFO regeneration process I'm going to suggest involves the use of extremely dangerous chemicals. Complete skin and eye protection should be worn during each phase of the regeneration process. If using this article as a guide for the GFO regeneration process, you are hereby understanding that myself (Jeremy Linzmaier) and/or the Fox Valley Reef Club are not liable for any injury that might occur.
OK. That sounds bad, but every disclaimer must. Yes, the chemicals are dangerous. Can this be done safely and easily with proper technique - absolutely!