PDA

View Full Version : How long does GFO last in a tank?


Nexenn
02/05/2010, 05:22 PM
Was thinking about adding some GFO in a reactor but I heard that the material doesn't last very long (approx 3 or 4 days).

I was wondering what experiences you all have add with the length of time GFO kept the phosphates down in your tank before having to put in more material.

Thanks

john90009
02/05/2010, 05:46 PM
well like your going to get from everyone else- it all depends on your system and how much your running. Many people will tell you never to dose or try to fix a problem if you dont know its specific parameters. please tell more on your tank size and what signs your seing that you want to change.

Nexenn
02/05/2010, 06:42 PM
well like your going to get from everyone else- it all depends on your system and how much your running. Many people will tell you never to dose or try to fix a problem if you dont know its specific parameters. please tell more on your tank size and what signs your seing that you want to change.

90 gallon display
30 gallon sump
New reef octopus 150 skimmer
use a filter sock on my overflow (replace it every 3 days)
grow chaeto in my fuge
1300 GPH return pump
2 - 800 GPH koriellas
small yellow, blue hippo and purple tang
black and white clown fish
mixed reef - some leathers, Xenia, mushrooms, zoos, etc...

Ammonia - 0
Nitrate - 0
Nitrite - 0
pH - 8.3
calcium - 420
Alk - 10 dkh
salinity - 1.025
Temp - 76-78.5
RO/DI water currently has a PPM of 1
Do 10-15% water changes every sunday

Wanting to move up to putting some SPS in there so I want my phosphates to be as low as I can. I also have a little bit of cyano algae growing on my sand bed that I would like to get rid of. I figured a reactor with GFO would be a good way to aid in that. However, I wasn't sure the length of time that the GFO would be effective in the tank.

Was planning on buying:
http://www.bulkreefsupply.com/store/1-pound-453-grams-bulk-gfo-granular-ferric-oxide.html

And using 1/3rd of it at a time so that it would last 3 replacements. This is also close to the accepted amount per gallon that should be used. However, this is just another cost and dont want to use it if it needs to be replaced once a week. Once every 3-6 months would be do-able. So I'm just looking at a ballpark figure of how long I can expect 1/3rd of a pound to last in my system. (1 day? week? month? year?)

thanks

lordofthereef
02/05/2010, 07:48 PM
If you have no phosphates to control, the GFO really isn't going to be absorbing anything. Test your phosphates.

undrtkr_00
02/05/2010, 08:02 PM
Don't know who told you it would only last 3 or 4 days, but they may have been confused.

I have a 110 (total volume similar to yours, and similar bioload). I change my GFO out about once/month and use less than the recommended dosage. BRS directions indicate that it should last 4-8 weeks.

http://www.bulkreefsupply.com/store/Granular-Ferric-Oxide-GFO-Instructions (http://www.bulkreefsupply.com/store/Granular-Ferric-Oxide-GFO-Instructions)

john90009
02/05/2010, 08:30 PM
Yes the gfo lasts way more then 3-4 days. Many factors could be contributing to that cyano- lights flow who knows two of my rocks grow cyano every day but when the lights start to turn off the cyano goes away- and my bulbs are new. Also The only way to get accurate readings on phosphate is with a hanna meter or something liek that- test kits wont show the true amount. I have a 120 gallon system and have basically the same setup but more fish. I run carbon to and i havent replaced my gfo in a few months and it definitely helps. Try moving out so soft corals first. Then try getting a free frag of a easy to keep sps- see how it does- 15% waterchanges weakly is alot to do with just softies. one guy who has one of the nicest tanks iv ever seen and phenomenal corals with crazy growth only does a 5 gallon water change weekly on a 180+ system. Everything depends on your system its all different. When i replaced my gfo i get a slight color change but you can tell when its going bad by how frequent the brown algae comes back on your glass- when its exhausted mine comes back in 5 days- when the gfo is working i use a mag float rarly.

luther1200
02/05/2010, 08:53 PM
I change mine once a month.

PSU REEFER
02/05/2010, 10:38 PM
Also change mine once a month.

lordofthereef
02/06/2010, 12:41 AM
The only reason I don't like the idea of giving a timeline is because we don't know what sort of phosphates the OP is battling. If the water is rich in Phosphates, initially he/she may go through GFO MUCH faster than once the system stabilizes. Many factors effect phosphates, but the number one for many people is probably the type of feed and how much is fed to the tank.

foodog
02/06/2010, 12:49 AM
Too many factors. Just check your parameters and adjust imo

shikhyung
02/06/2010, 08:39 AM
How do you know when it time to change?

john90009
02/06/2010, 08:44 AM
the only true way to tell is to have a hannah meter. Some people who run there tank like clock work that know exactly how much thy feed daily can figure a few days before minor signs of phosphates in the water will figure to change it a few days before.

sabbath
02/06/2010, 09:16 AM
I have to change mine every 5 or 6 days. If i see macro starting to grow again. Then it is time to change it.

I use 1 1/2 cups of reg. BRS in a loaded 75g mixed,filter sock changed every day, Octx200 skimmer w/bb3000 pump.

rkb
02/06/2010, 09:35 AM
This how I run GFO in my 40B- we can agree that hobbiest grade PO4 tests are pretty crappy and if you have fish and feed them you are introducing PO4 to the tank. Even though my Red Sea test indicates zero I'm sure that the phosphates are there, just in very small amounts. So, to remove the phosphates before they reach a detectable level I run one gram of GFO per gallon of water in my system. With sump, overflow boxes, etc that comes to around 60 gallons and 60 grams of GFO in a Phosban 150. Water flow through the unit is a very slow tumble. The question of when to change, as I never get a positive test for phosphates you will have to rely on simple observation of the tank for clues. For me this is very simple- with new GFO I only have to scrape the glass every few days. And what I'm scraping is more whiteish in color. As the GFO ages I scrape more often and the algea has a green/brown color to it. In my system this takes about one month for the GFO to reach the end of it's life and need changing.

bbris
02/25/2010, 11:07 PM
This is some really nice and well presented info here. Thank you. One more question that was not address. BRS has granular and pellet GFO. Any preference here?
Thanks in advance.

Bill

sabbath
02/26/2010, 06:21 AM
This is some really nice and well presented info here. Thank you. One more question that was not address. BRS has granular and pellet GFO. Any preference here?
Thanks in advance.

Bill

I'm going to switch to pellets next time. Finding that after about 3 days mine starts to clump up and gets pushed to to top of the reactor. Thinking that the pellets will allow the water to go around even if they are fusing together some.

bbris
02/26/2010, 08:57 PM
Interesting - Sounds possible. Someone else suggested they might be more 'hydrodynamic'.
Bill

Eric45
06/12/2011, 01:29 PM
I have to change mine every 5 or 6 days. If i see macro starting to grow again. Then it is time to change it.

I use 1 1/2 cups of reg. BRS in a loaded 75g mixed,filter sock changed every day, Octx200 skimmer w/bb3000 pump.

Seems like I have to change mine every week or the bryopsis goes nuts. Is this a forever thing? I really don't feed them too much and I vodka dose which seems to be great for nitrates, but i'm less sure about PO.

So how often do folks dose GFO anyway?

biecacka
09/25/2011, 08:11 AM
they also make one more for filter socks i think
corey

tkeracer619
09/25/2011, 09:04 AM
hours or a month+

It all depends on how much phosphate you have in the tank.

sabbath
09/25/2011, 09:10 AM
I'm running BRS HC GFO in the reactor that looks like a di filter. (I really like this reactor over the two little fishes ones.) I find that I have to regenerate them once every 7 to 10 days. This is with vinegar dosing to maintain 1-2 no3.

Sent from my mobile

jimroth
09/25/2011, 09:11 AM
I switched from granular to BRS pellets in my reactors. One thing to note is that I had to way incease the flow to get the same effect from the pellets, they need to be really tumbling to get that the same phophate reduction. Something about having less surface area.

biecacka
09/25/2011, 05:59 PM
has anyone used the stuff that goes right in your filter socks?
corey