Does GFO lower Alk and cause my SPS to RTN/STN?

[dviper150]

After reading this and double checking my chart where I have been monitoring my Alk and rest of parameters, I didn't see a drop in my Alk besides the amount that is used up on a day to day basis by my corals. Its been a month exactly today since I started the reactor with gfo and have brought my phosphates down from .8 to around .15 today. I have a lot of sps and zoas. I am running 2.5 cups on a 150g total system of the regular GFO from premiumaquatics at medium tumble using MJ900. I have found that keeping it at low tumble tends to eventually clog up the reactor and the water doesn't flow fluently/evenly around the gfo in the reactor. It eventually just starts flowing through only one small section. I upped the flow a little and so far, no clogging or stagnant areas.

 

[Ted_C]

How do you think it will do that? I don't think it does reduce carbonate alkalinity other than if a lot of precipitation occurs on the media which would have little to nothing to do with flow ,ime tending toward more of that if anything at lesser flow,ime.
Ddh drops are likely to be insignificant from the gfo itself. The enhanced bio activity and consumption of alk and calcium resulting from cleaner water, more light and less PO4 are the major players ,imo and ime.

BTW, PO4 is alkainity,we just don't want very much of it as part of the total alkalinity.

What other informative avenues related to GFO are you talking about?

+1
There's no mechanism I know that takes FeO or Fe2O3 and reacts with Carbonates. The affinity for Carbonates to Iron just isn't there.

 

[domvert]

150 gal

150 gal

on a 150 gall you are running 2.5 cups of GFO??
Thats seems like a lot to me-

 

[keithhays]

I don't think the problem is the lowering of the alkalinity. You would be measuring a difference if that were the case. The lowering of alkalinity is in the immediate vicinity of the effluent, not in the overall tank.

It is much more likely that your animals are used to higher levels of phosphate and quickly stripping it out is affecting them adversely.

 

[overklok]

It looks like you are in an Ultra Low Nutrient situation, you should get your alkalinity into the 7.5 dKH area.

 

[mooch1982]

I don't think the problem is the lowering of the alkalinity. You would be measuring a difference if that were the case. The lowering of alkalinity is in the immediate vicinity of the effluent, not in the overall tank.

It is much more likely that your animals are used to higher levels of phosphate and quickly stripping it out is affecting them adversely.

I have to agree here. GFO is often a problem when it strips the tank of phos too fast.

I run 3x the amount of HC GFO on my nano with 37 SPS frags. Non have STNd due to GFO, and my phos has always run low.

Rapid changes in phosphate is when problems start.....

 

[FlyPenFly]

Literally this is happening to me right now.

Brought a much bigger GFO reactor online with a much larger amount of GFO with far more flow... alkanity took a literal nose dive. It happened in 1-3 hours which leads me to believe that shocking the system with a large amount of lots of GFO is causing this phenomena and the media is somehow causing alk to drop.

I went from 10 dkh and I'm struggling to maintain 8 with soda ash. Cutting back flow on the gfo.

It's been about 8 hours total, seeing base recession on ALL my SPS from acros to bird's nests.

I wonder if the iron itself is somehow responsible for alk precip?

 

[bertoni]

The GFO can cause precipitation due to local pH changes:

http://reefkeeping.com/issues/2004-11/rhf/index.htm

I am not sure what you mean by the iron causing precipitation. I don't think iron leaching from the GFO will do that, if that's what you mean.

I would turn off the GFO for the time being, personally.

 

[FlyPenFly]

I did and my alk stopped its nose dive.

Lesson learned, really use the recommended amount...

My assumption was that gfo was purely a binding material so a larger amount of it would simply allow me longer leeway in the messy job of replacing the gfo. I did not realize the material itself would have a serious effect on alkalinity in a direct manner.

 

[tmz]

"...Finally, it appears that ferric ion (Fe[SIZE=-1]⁺⁺⁺[/SIZE]) may help initiate the precipitation of calcium carbonate. Such ions may be added directly in some products, and can be released from iron-based phosphate binders such as Rowaphos, Phosban, and Phosphate Killer...."

From this:

http://reefkeeping.com/issues/2005-07/rhf/index.htm