Gfo

[maroun.c]

What are your thoughts on keeping GFO in the reactor for a long time?
Does it release PO4 as it gets saturated or not? In my case i dealing with higher PO4 and trying to drop it gradually. Prefer not to have to take the reactor out for cleaning and just add to it on weekly basis. Any issues with that?
Thanks.

 

[MattL22]

Good question I change mine every week the day after my weekly wc ATM because my nutrients r always high between my sand bed and lots of fish

 

[MattL22]

Many change it every few weeks all depends on how high ur po4 is

 

[Randy Holmes-Farley Verified Community Expert]

If it becomes saturated at one phosphate level and then the tank drops to a lower level, some will come off. Phosphate on GFO is in an on/off equilibrium with phosphate in the water. Also, the higher the water concentration of phosphate, the more binds to it.

 

[maroun.c]

Thanks for the replies. So at higher phosphate levels it would be safe to keep it longer then?

 

[Randy Holmes-Farley Verified Community Expert]

It is generally safe to keep it in if the phosphate level is steady at any level. But if phosphate goes down for other reasons, it may desorb from the GFO.

It will also likely start to grow bacteria and may be coated completely after a few weeks.

 

[maroun.c]

In my case I'm having to change/add every 4-5 days till I get the levels down. So the reactor will get filled after 2-3 additions so 2 weeks or 3 at max.

 

[Libimagana]

In my case I'm having to change/add every 4-5 days till I get the levels down. So the reactor will get filled after 2-3 additions so 2 weeks or 3 at max.

I tough I was the only one seen this issue with gfo mine I always have phosphate between .25 and .5 and I keep mine in the cascade filter

 

[Eric N]

As mentioned above, phosphate adsorbed on the GFO is in an equilibrium with free phosphates in the water, so if you removed the phosphates by an alternative method and left the saturated GFO in there it would release some of the phosphate. I'm not sure how much or whether its a significant amount, but it's one way. pH and alkalinity effect Iron oxide's ability to adsorb phosphates, so I imagine an increase in either one would cause the GFO to release the phosphates back in the water. I can imagine someone with saturated GFO noticing a rise in phosphates so they do a hasty water change that reduces phosphates and causes a spike in pH and alk. and a subsequent spike in phosphates.

 

[maroun.c]

Thanks for all the replies guess it just makes sense in the end to take out that reactor and replace the GFO instead of adding to avoid all that.

 

[LarrySmith75]

When testing for phosphate. Is it better to test from the display, the sump , or the output hose from the GFO reactor?

 

[Randy Holmes-Farley Verified Community Expert]

When testing for phosphate. Is it better to test from the display, the sump , or the output hose from the GFO reactor?

Comparing the display to the reactor output will tell you whether the GFO is depleted or not. It is the display that matters for the creatures and algae.