Need Advice About GFO

[FireEMT]

I would like to hear what drawbacks there are about GFO reactors. It seems like GFO is a good option for phosphate but then I hear about it raising salinity. So then I started to look into biopellets but then there are drawbacks to that too. Biopellets also seem like a good option because they take care of nitrate and phosphate. I'm lost and don't know what to do. I will be dosing Ca, Mg, and Alk and I like the idea of Fauna Marin balling light trace elements added to that. Any advice would be much appreciated.

 

[Randy Holmes-Farley Verified Community Expert]

GFO has zero effect on salinity.

Aside from using too much so phosphate goes too low, the only drawback is that it may supply iron, which, if your algae or cyano is iron-limited, might grow faster. Cost, of course, is a drawback.

Biopellets often are too lobsided toward too much N relative to P to export both fully, and so GFO or some other phosphate export mechanism may be needed.

 

[FireEMT]

GFO has zero effect on salinity.

Aside from using too much so phosphate goes too low, the only drawback is that it may supply iron, which, if your algae or cyano is iron-limited, might grow faster. Cost, of course, is a drawback.

Biopellets often are too lobsided toward too much N relative to P to export both fully, and so GFO or some other phosphate export mechanism may be needed.

Thanks for the info Randy. With that being said what is the benefit of BP are they just good at removing N and thats what makes them a good option or is there something else. With your recommendation I will be running GFO most likely and a good skimmer for the nitrate because I will not have a refugium. Maybe Marine Blocks but haven't decided.

 

[jonbar1]

Only drawback I've found with GFO is the price of replacing it and needing an expensive test to measure phosphate like a Hanna to know when to replace it.

I've never ran Bio Pellets but have dosed vodka in the past. Here you are limited by how good your skimmer is. When I dosed vodka I eventually had a dino outbreak that I cannot attribute to anything else, so now I'm pretty skewed against it.

 

[FireEMT]

Only drawback I've found with GFO is the price of replacing it and needing an expensive test to measure phosphate like a Hanna to know when to replace it.

I've never ran Bio Pellets but have dosed vodka in the past. Here you are limited by how good your skimmer is. When I dosed vodka I eventually had a dino outbreak that I cannot attribute to anything else, so now I'm pretty skewed against it.

How do you determine when its time to change? Do you wait for the phosphate to just raise a little or do you wait for some significant point?

 

[jonbar1]

When phosphate level coming out of reactor isn't lower than coming into it I change it.

 

[Reab]

If your phosphate isnt that high, id find a place for some cheato and have that remove the nitrates/phosphates as it grows. The only problem with GFO that i see is it really only acts as an expensive band aid

 

[ReefMadScientist]

GFO all the way. I ran a BP reactor once and its bulky, goes in your sump, and is like a skimmer pretty much.

For my GFO, I ran it for a few months until my PO4 hit undetectable levels. I simply turned off my GFO and am at a steady 0.00 to 0.02 now. If PO4 ever goes up past .02 I will just turn the GFO on. Much more flexibility with this I believe.

And yes I dose 2-part.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for the info Randy. With that being said what is the benefit of BP are they just good at removing N and thats what makes them a good option or is there something else. With your recommendation I will be running GFO most likely and a good skimmer for the nitrate because I will not have a refugium. Maybe Marine Blocks but haven't decided.

I discuss the pros and cons of biopellets and other methods of nitrate reduction here:

Nitrate in the Reef Aquarium - REEFEDITION
https://www.reef2reef.com/blog/nitrate-in-the-reef-aquarium/

from it:

7. Biopellets

Biopellets are typically organic polymers (often PHB, polyhydroxybutyrate; shown below)):

Polyhydroxybutyrate

These polymers can very slowly degrade in sterile water, but in an aquarium, bacteria settle on them and release enzymes that chop up the polymers into smaller bits (such as hydroxybutyric acid, the building block of this polymer) much faster than the simple hydrolysis reaction would proceed on its own. PHB is a natural energy storage molecule for many bacteria, and so some bacteria are accustomed to making it and degrading it internally. Some bacteria earn a living by being ready to degrade such polymers when they encounter them outside their bodies (for example, from other bacteria that have died) and these bacteria release enzymes into the water to break down the polymer pellet. They then take up the released hydroxybutyric acid and metabolize it to gain energy.

In an aquarium setting, bacteria will coat the pellets, and digest much of the polymer themselves, using up nitrate and phosphate in the process as they grow and expand their tissues. Some of the released hydroxybutyric acid will make its way into the bulk water, so bacteria can also grow remotely from the pellets (including cyanobacteria). Consequently, it is not as confined of a process as is a carbon denitrator, even though it is usually carried out in a flow reactor.

This method can use slightly more nitrate than a proportional amount of phosphate if the bacteria form a thick enough layer on the pellet. In that case, the bacteria on the bottom (the pellet surface) can be oxygen limited, and may use nitrate as an electron acceptor (source of oxygen) as happens in deep sand beds, in addition to the N and P used to make their body tissues.