GFO- How much?

MichaelReefer

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I did some reading on GFO and ordered myself a reactor but some things worry me. I saw if you use too much you can cause issues with your tank. The GFO says 1/2 cup per 25 gallons. Because it's my first time using GFO should I use less, just to dial it in?


Appreciate any help!
 
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madweazl

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I did some reading on GFO and ordered myself a reactor but some things worry me. I saw if you use too much you can cause issues with your tank. The GFO says 1/2 cup per 25 gallons. Because it's my first time using GFO should I use less, just to dial it in?


Appreciate any help!
Do you actually need GFO? If your phosphates arent over about .2ppm and climbing, I wouldnt use it. As for the amount, I'd stick to using it as directed.
 

Bryknicks

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What is the PO4 level on the tank now? What are you trying to bring it to? I would start with 1/8-1/4 cup per 25 gallons and see where that brings your PO4. When I hooked up my reactor I started with half the recommended dose and bottomed out my PO4 and got dino's. The idea is that you want to keep PO4 levels above .02-.03 in order to prevent dinos. If you aren't testing for PO4 then I would buy a good test kit (Hanna low range phosphate) first and start testing before hooking up the reactor.
 

madweazl

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What is the PO4 level on the tank now? What are you trying to bring it to? I would start with 1/8-1/4 cup per 25 gallons and see where that brings your PO4. When I hooked up my reactor I started with half the recommended dose and bottomed out my PO4 and got dino's. The idea is that you want to keep PO4 levels above .02-.03 in order to prevent dinos. If you aren't testing for PO4 then I would buy a good test kit (Hanna low range phosphate) first and start testing before hooking up the reactor.
Any amount can bottom out your phosphates, use the flow rate to regulate that.
 

Bryknicks

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Any amount can bottom out your phosphates, use the flow rate to regulate that.
I think it is easier to control the amount of GFO used vs. the flow rate, especially for a beginner/inexperienced user. I've also read that the GFO should have a slight tumble to ensure the proper flow rate. Either way, I've taken mine offline as my phosphate levels now stick between .04-.06
 
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jda

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I would use a very small amount, use lower flow and change it more often. If you have higher P in the water, then you have a bunch bound to the rock and sand too... so you need to lower it slowly so that the rock and sand can unbind at the same rate or else you lower the water amount too much in a downward spike, then the rock/sand releases and you spike back up.

Take a wholistic approach where you consider the reservoir in the aragonite and you will be OK. Just worrying about the water concentration is where people get into trouble since this is a really small amount and can lower VERY quickly.
 

90's reefer

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What is the PO4 level on the tank now? What are you trying to bring it to? I would start with 1/8-1/4 cup per 25 gallons and see where that brings your PO4. When I hooked up my reactor I started with half the recommended dose and bottomed out my PO4 and got dino's. The idea is that you want to keep PO4 levels above .02-.03 in order to prevent dinos. If you aren't testing for PO4 then I would buy a good test kit (Hanna low range phosphate) first and start testing before hooking up the reactor.
Good advice!
If you dont test you wont know.
I like phosgaurd myself as its less messy.
Through some in a mesh bag at 1/4 the recommended dose into your sump.
Test every 24 hours. When level wanted is reached remove and test daily to see if it goes up.
If it goes up add mesh bag and repeat.
What size tank and what are current po4 levels?
With a reactor it is very easy to remove all po4 very quick which will lead to other issues.
Go slow with minimal amounts used to lower po4 over at least a week period of time. Longer if levels are very high.
 
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MichaelReefer

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Good advice!
If you dont test you wont know.
I like phosgaurd myself as its less messy.
Through some in a mesh bag at 1/4 the recommended dose into your sump.
Test every 24 hours. When level wanted is reached remove and test daily to see if it goes up.
If it goes up add mesh bag and repeat.
What size tank and what are current po4 levels?
With a reactor it is very easy to remove all po4 very quick which will lead to other issues.
Go slow with minimal amounts used to lower po4 over at least a week period of time. Longer if levels are very high.

I am getting a test kit tonight, but I know they are a little high due to Dinos and small amounts of Slime Algae.

I am also going to put carbon in it too.
 

Backreefing

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The best amount of GFO is nothing, zero . If you think you got dinos now put some GFO in there watch as corals die , and Dino’s grow like fire .
then comes red cyano .
it’s you aquarium. Good luck and happy reefing .
 

SuncrestReef

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Be aware that GFO will also cause your alkalinity to drop rapidly as soon as you add it. Be sure to test your alk right before starting GFO, then test it again a couple hours after GFO and dose alkalinity accordingly.
 
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