How Often Do You Change GFO

[bif24701]

My phosphate level is unchanged after two days. It's staying at .23 does mean I need to change GFO, I got this tank from a friend and phosphate level was 1.3.. Thanks

See above post:

Are you measuring the reactor output or your tank water?

 

[girish5657]

i have 0.25 ppm reading on api test kit how much gfo need to bring down at minmum in reactor

 

[Hitch08]

I have two reactors. One for Carbon and one for GFO. I don't change either often enough. The annoyance is flushing out the fines. I haven't found a good way to do it since my reactors run off of the main pump. Maybe I'll get a small pump to flush the fines into the sink. The other issue is that the tubing from the pump feed to the reactor is very hard to get on and off. That's really my issue.

Anyway, my answer is not often enough. Sometimes up to 8 weeks. I have too many long spine urchins and they mow down the algae.

 

[Bpb]

However often is necessary. PO4 testing should be done to maximize its usefulness. Otherwise you may just be either running excessively high PO4 with depleted media, or worse, throwing away perfectly good GFO that doesn't need to be changed. Pick up a hanna checker, and a box of reagents. Test every 2 weeks. It'll last you just shy of a year. Whenever your PO4 gets higher than your ideal range, change it out. Thats my plan anyway. 1/2 the recommended amount on my 90 gallon recently managed to knock my PO4 down from 0.21 ppm to 0.06 in just a couple days. I just let it ride until it climbs past 0.1 and then I'll change it for 1/2 strength again. Full strength will bring PO4 too low. Zero is bad. Zero equals reduced PE, STN, and angry corals all around

 

[Reef Frog]

For me, running mechanical filtration helps extend the life and effectiveness of GFO, and can stretch your maintenance intervals a little bit. It keeps the foam pads in the upflow reactor stay cleaner for a longer time. So the water moves better longer, the granules vibrate as they should, flow doesn't slow down, there is less organic decomposing going on and less caking. What's not to like, huh?

I have proven all this to myself many times over the years when I decided to run with mechanical filtration removed for a time, but still kept the GFO reactor on line & running. In these cases flow would slow down early, I could see channeling happening in the media which means some water is going in the tank only through an exhausted vein of media whole other parts are not being used and are stagnating.

Also the proper pump size aka flow is critical, and making sure your reactor is level helps a lot.