How effective is GFO

[Gtinnel]

My current tank is around 2.5 years old and up until the last few months my phosphates always stayed around .05 maybe occasionally creeping up towards .1. Then about 3 months ago they started getting up closer to .3, so I would throw a media bag of gfo in my sump when needed until I got a refugium setup. The refugium seemed to work until about a month ago when I noticed my phosphates were creeping up again.

I tested my phosphates 3 days ago and it was .11 (a little higher than I'd like but nothing I'd worry about) and then when I tested this evening I got .58, which is weird because in the days between these tests I barely fed the tank because of me being sick. I then threw a media bag with about 6 tablespoons of gfo in my sump. I just tested my phosphate again which was about 6 hours after adding the gfo and I'm getting a reading of .07. Is this even possible, 6 tablespoons of gfo in a media bag (which I know is the worst possible application of gfo) couldn't have dropped my phosphates in a 125g tank from. 58 to .07 in 6 hours could it? I'm starting to think I'm getting false readings.

Also, I am using a Hanna ULR Phosphate checker and before someone asks my nitrates stay around 3-5 tested with the HR Hanna checker, and the chaeto in my sump is growing fine.

 

[jx.reef]

I didn’t have much luck running gfo in a media bag. I recommend using a reactor. I have crazy high phosphate now and actively running 10g of phosfiltrum on a 100 gallon gets from 1.2 to 0.75

edit: misread your original post but yes, gfo is incredibly effective and will drop your phosphates very quickly. Using 85 grams could easily drop you to zero

 

[Gtinnel]

I knew in a media bag wasn't a very good application and overall I don't really want to run GFO long term, but i will if necessary. I was getting ready to setup an old reactor that I had sitting around when I retested my phosphate and got the .07. Really what I'm wanting to know is if I should expect my first reading of 58 was false, ecspecially since I was using a fairly small amount of gfo in the worst way possible.

 

[Mastiffsrule]

Possibly a testing error at some point?

 

[crvz]

I would suspect you had a bad test for that kind of 3 day delta in po4 values. I think GFO can be effective, and I employ it myself at times, but it’s more of an aid than a solution.

 

[Gtinnel]

Possibly a testing error at some point?

That's what I'm leaning towards and I may have a suspicion of why. I have a bad habit of keeping a glass cup sitting near my tank that I use for many thing including thawing out frozen food and occasionally getting a scoop of water for testing, when im testing multiple parameters. I'm wondering if there was a little bit of dried food in the cup that was causing my higher reading.
Tomorrow I think I'm going to test from water scooped out with that cup and water I get directly from the tank with the syringe and see what if any difference I get.

 

[Gtinnel]

I would suspect you had a bad test for that kind of 3 day delta in po4 values. I think GFO can be effective, and I employ it myself at times, but it’s more of an aid than a solution.

Yes and in those 3 days I barely fed the tank because I was sick and spent two of those days in bed.

 

[Gtinnel]

I know gfo can be very effective at removing phosphate but it can't possibly be that effective can it, ecspecially just in a bag and not tumbling in a reactor?

 

[Gtinnel]

So this morning I tested my phosphate levels again and with scooping the water out of the tank with my handy glass I got a reading of .41, which is lower than yesterday but still way too high for me. I then used the pipette to get the water directly from the tank and my phosphate was .03.

So for the last 3 months I've been chasing a phosphate number that was just me doing something stupid in my testing procedure.

 

[Pistondog]

So this morning I tested my phosphate levels again and with scooping the water out of the tank with my handy glass I got a reading of .41, which is lower than yesterday but still way too high for me. I then used the pipette to get the water directly from the tank and my phosphate was .03.

So for the last 3 months I've been chasing a phosphate number that was just me doing something stupid in my testing procedure.

You can scoop the water, but rinse the vial in tap water after capping. Otherwise the salt film after drying might skew the optical readings.
I also have a red sea phosphate test kit to verify if somethings suspect.

 

[Gtinnel]

You can scoop the water, but rinse the vial in tap water after capping. Otherwise the salt film after drying might skew the optical readings.
I also have a red sea phosphate test kit to verify if somethings suspect.

It wasn't even the vial I was getting the water out with. I keep a glass up by the tank that I use to scoop out water when doing multiple tests and sometimes I'll defrost fish food in that cup. It was the remnants of dried fish food skewing my results.
My vials for the Hanna checkers I rinse and the store full of rodi after using them.

 

[crvz]

Yeah, been there. Glad your levels are good, but sorry you learned something the hard way.

 

[Gtinnel]

Yeah, been there. Glad your levels are good, but sorry you learned something the hard way.

I'm just glad I figured it out. Not being able to get my phosphates under control was driving me insane. At least I didn't do anything drastic that could've been detrimental to the tank before I figured it out.

 

[Jaredtexas]

GFO is super effective in a reactor to the point it’s annoying. Have been running the same amount for 4 months and has worked great to keep the phosphate down to about .03… added to much in the reactor last water change and it’s been At straight zero. I can pretty much spot when it plummets now because it’s super obvious in the acros. Been heavy feeding to try and bring it back up.

 

[Greg P]

I'm just glad I figured it out. Not being able to get my phosphates under control was driving me insane. At least I didn't do anything drastic that could've been detrimental to the tank before I figured it out.

Yes, you could have started adding NO3 to drop the PO4 and ended up with a nasty bloom of something you'd now be chasing without knowing what the heck is going on !!

 

[Gtinnel]

GFO is super effective in a reactor to the point it’s annoying. Have been running the same amount for 4 months and has worked great to keep the phosphate down to about .03… added to much in the reactor last water change and it’s been At straight zero. I can pretty much spot when it plummets now because it’s super obvious in the acros. Been heavy feeding to try and bring it back up.

No I would only run gfo when my testing (which I now know was not trustworthy) was high and then I would put a small amount of gfo in a media bag in the sump. And that only started 3 months ago, before that I never had a phosphate level high enough to warrant gfo.
I also never used a reactor with gfo.

 

[Gtinnel]

Yes, you could have started adding NO3 to drop the PO4 and ended up with a nasty bloom of something you'd now be chasing without knowing what the heck is going on !!

Yes I was getting ready to aggressively remove phosphate with increasing my refugium lighting time, adding extra nitrates, and running a reactor for gfo.

I'm glad I didn't drop my phosphates to zero without even knowing it.

 

[131696]

Coral euphoria uses it on YouTube only thing he uses for years so it works look at his tanks

 

[Gtinnel]

Coral euphoria uses it on YouTube only thing he uses for years so it works look at his tanks

There are plenty of people that successfully use gfo to keep phosphates down, I don't question that it is an effective tool. I don't want to use gfo regularly because I get lazy with common maintenance tasks, so I know I wouldn't change it as often as needed. I ran my tank for several years with a AWC and a skimmer as my only filters and never had a nutrient issue. It wasn't until 3 months ago that it became a problem, which again it wasn't actually a problem, I just was doing something stupid. I honestly setup a fuge that I probably don't even need, but I like the pH boost at night so I will be leaving it even if I don't really need it.

 

[Greg P]

I ran GFO religiously in a reactor from 2012 until 2016 because it was what was 'recommended' as 'the norm' for keeping a mixed reef tank.
You HAD to run GFO if you wanted to keep a reef tank.
I stopped running it as I started to see negative effects from the iron content. It was not reducing PO4 enough to combat rising algae levels.
After removing GFO from my system, I started to see a reduction in nuisance algae.
I then noticed I needed to add NO3 and PO4 to keep my corals happy.