Too much GFO?

WallysWorld

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I’ve seen several comments that using too much GFO is bad. How do you know when you’ve used too much?

I just installed a reactor and am using a mix of Rox Carbon and Granular GFO (not high capacity) from BRS. The amount of GFO for my 80 gallon tank according the the instructions resulted in 1.25 cups (1 TBSP/4 gallons). This seemed like a lot so I put 3/4 cup in the reactor mixed with 3/4 cups of carbon. My phosphates were high ~0.2 ppm, but came down pretty quickly over a week to 0.04 ppm, which I’m happy about. I believe that the phosphate was(is?) leaching from my rock. When do I start worrying about too much GFO?
 
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That's a pretty quick phos drop.

Imo, Keep on testing and ensure your phos doesn't keep dropping. If you're pulling more out with gfo, then your rock and feeding are adding, you've got too much in there and run the risk of zeroing out.
 
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I’ve seen several comments that using too much GFO is bad. How do you know when you’ve used too much?

I just installed a reactor and am using a mix of Rox Carbon and Granular GFO (not high capacity) from BRS. The amount of GFO for my 80 gallon tank according the the instructions resulted in 1.25 cups (1 TBSP/4 gallons). This seemed like a lot so I put 3/4 cup in the reactor mixed with 3/4 cups of carbon. My phosphates were high ~0.2 ppm, but came down pretty quickly over a week to 0.04 ppm, which I’m happy about. I believe that the phosphate was(is?) leaching from my rock. When do I start worrying about too much GFO?
You now know what 3/4 cups can do. Next time you need to bring down PO4, to 0.02 ppm, you will be able figure out roughly how much to add. Err on adding less and taking longer to reduce the level. Keep measuring PO4 and when it creeps up again add fresh GFO, but less than 3/4 cups.
 
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