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Discussion Starter · #1 ·
Hi everyone.

So before i start here are my tanks prams.

Nitrate=0
Nitrite=0
phosphate=really low(undetectable)
Salinity=1.025
Magnesium=1350ish
calcium=480ish
alkalinity=10.4
PH=8.35
Temperature=79.5-80.5 throughout 24 hours

Thats all im testing for atm.(I have an ammonia alarm too so i don't test for it.)

So about a week ago i noticed some gha starting to grow and immediately did a 20% water change and purchased a phosphate test kit which showed that indeed my phosphates were elevated. I installed a reactor and put in the recommended dose of GFO for my tank size (46 bowfront with 15g custom sump refugium). After a few days i tested again and saw that my phosphates had dropped to almost undetectable levels. My question is, How long does it usually take to see a noticeable difference after adding GFO to a system? I'm specifically asking about the appearance of the tank not the levels of po4 present in the water. anyways let me know what you guys think.

Have a great day!!
 

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Fry Daddy! Multiple tanks, reef, seahorse
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I really can't answer that question . I use GFO and even then I have some GHA , my test are like yours. Then I read where people have GHA use it and in a matter of days it dies. Then others say it don't work.
 

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Adding GFO was a good step, but I would not trust PO4 test kits so much. GHA is your best PO4 test kit, unfortunately. I would give it some time, maybe a week, to see results.

When I was fighting GHA, I did 4 things:

- added GFO
- reduced feeding
- use turkey buster to blow off the rocks
- increased Mg to 1500

I am not sure which thing did the trick, maybe none of them, btw, but GFO started dying.
 

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GFO relies on a chemical reaction to irreversibly bind phosphate.

2Fe2O3(s)+4PO4(AQ)->4FePO4(s)+3O2(AQ)

Therefore it should work instantly. Additionally you can 'see' it working. Ferric phosphate is much lighter in colouration than ferric oxide.
 

Hydro-Dynamic
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Adding GFO was a good step, but I would not trust PO4 test kits so much. GHA is your best PO4 test kit, unfortunately. I would give it some time, maybe a week, to see results.

When I was fighting GHA, I did 4 things:

- added GFO
- reduced feeding
- use turkey buster to blow off the rocks
- increased Mg to 1500

I am not sure which thing did the trick, maybe none of them, btw, but GFO started dying.
Increasing Mg by use of Kent Marine specifically, is excellent at fighting bryopsis.
Have not heard what it is in Kents make up that accomplishes this, but
increasing Mg can cause the Ca to precipitate according to the Tropic Marin
rep I spoke to.

As for timeframe, to do a lights out for a couple days will accelerate the effects.

For the OPs params, I would start bringing the Ca, Mg and Alk back down into
normal params, but would be nice to know how established the tank is
and what inhabits it. Since many SPS balk at higher Alk (as well as low)
it would be better for most sea creatures to be closer to natures params.
 

Hydro-Dynamic
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Oh, and BRS is notorious for poor directions on their GFO. They OVERDO it.
Starting with more than 2 TBSp on a 46g tank may well cause damage
to many coral. Of course we don't even know if this is a FOWLR tank or not.
The surface of the GFO should tumble some but not much.
Then after the 1st 3 or 4 wks you might, increase the flow to where the surface
and maybe 50% of the media is tumbling (2 TBSp maybe 100% slowly moving about,
slowly exchanging position with the top layer, nothing getting up into the mid section of the reactor
but you get the idea, low flow, and minUte amounts especially to begin with)
 

Hydro-Dynamic
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13,156 Posts
Though I don't agree with the amount used in this video
I think you could build up to 1/3C on a 100g tank just fine.
I ran 1/4-1/3 on my 100g tank with 4 fish and bare bottom
This is a bow front tank and the results came out really nice
following a 3 day lights out and GFO addition…

Then a month later (GFO for a week) they shot another video of the same tank
and showed the media tumbling near the end, at a little heavy flow
just to get an idea visually where you should be flow wise, a little slower >>>

You don't have to agree with everything or use the same media or equipment
but this is a great example of how to do GFO. I like the way he mentioned to
put the outlet into a bucket and run the water from the sump through it
discarding the first couple gallons to rinse it ;)
 

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Discussion Starter · #8 ·
thanks for all the replies guys.

just to answer some questions people had, it's a sps dominated tank(first sps dedicated tank) with a few lps and gorgonians. The tank is almost 9 months old(my first tank just turned 7 years old yay!) I feel that my prams are within an acceptable range and i don't plan to change them as they tend to dip slowly between water changes anyways. I'm running 1/4 cup(LFS recommendation not gfo sellers) atm and my acro's and monti's look great and show no signs of deterioration, rather they seem to be looking much better now that the phosphates are at acceptable levels. Ill give the gfo a couple more weeks and see where we are at that point.

Thanks again.
 

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Oh, and BRS is notorious for poor directions on their GFO. They OVERDO it.
Starting with more than 2 TBSp on a 46g tank may well cause damage
to many coral. Of course we don't even know if this is a FOWLR tank or not.
The surface of the GFO should tumble some but not much.
Then after the 1st 3 or 4 wks you might, increase the flow to where the surface
and maybe 50% of the media is tumbling (2 TBSp maybe 100% slowly moving about,
slowly exchanging position with the top layer, nothing getting up into the mid section of the reactor
but you get the idea, low flow, and minUte amounts especially to begin with)
I could never understand what this kind of recommendation (so much GFO per unit of the tank volume) could be based on. The PO4 conversion rate obviously must depend not only and not so much on the amount of GFO one put in the reactor as on the water flow rate through the reactor and reactor geometry.

So my recommendation would be to start very low, maybe 1/2 or even 1/4 of the recommended amount and raise if after a week if there is no effect on algae or lower it if there is a damage to corals.
 

Hydro-Dynamic
Joined
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I could never understand what this kind of recommendation (so much GFO per unit of the tank volume) could be based on. The PO4 conversion rate obviously must depend not only and not so much on the amount of GFO one put in the reactor as on the water flow rate through the reactor and reactor geometry.

So my recommendation would be to start very low, maybe 1/2 or even 1/4 of the recommended amount and raise if after a week if there is no effect on algae or lower it if there is a damage to corals.
yup that's why I suggested to start low flow and increase the effluent after a couple weeks since we were in the dark as to tank specifics other than size.
I had no idea if the tank was a single damsel or as unveiled, SPS dominant.

I've seen alk "burn" at 11 and 6-ish
 
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