Frogmanx82
New member
Phosphate is 1. If I use a liter in a 90 gallon tank is it a matter of weeks or will I get months?
How long will GFO last in a filter
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lordofthereef
One reef to rule them all
I think that depends on how much phospahtes are being "produced" as well. If it is 1 now, and there is none being introduced (which I doubt) it probably won't all get used up. I would simply keep testing and see how low it gets and if it starts moving back up.
Phosphate is 1. If I use a liter in a 90 gallon tank is it a matter of weeks or will I get months?
If phosphate is 1 ppm, it might be a matter of hours, not weeks or months, depending on how much you use and how you use it.
The less you are expecting it to bind, the longer it lasts.
If phosphate is 1 ppm, it might be a matter of hours, not weeks or months, depending on how much you use and how you use it.
The less you are expecting it to bind, the longer it lasts.
Frogmanx82
New member
Thanks doughboy for digging up that excellent thread. A liter of high quality GFO from BRS should take my phosphate down pretty quick and hopefully get my hair algae in check.
Yes, a liter is a very large amount. I didn't notice that at first. I'd be careful it is not too large.
I knew Randy would catch that.I agree a liter is probably too much at once for a 90 gallon tank in my experience. Rapid depletion of PO4 could be harmful. Starting with less, say 200ml and measuring the decline would be safer.
FWIW I use about 600ml on a high bioload well fed 550g system with a monthly change.
FWIW I use about 600ml on a high bioload well fed 550g system with a monthly change.
Frogmanx82
New member
Thanks, yeah I wouldn't add a liter at once. I have been using Kent phosphate sponge but you can only have that in the filter for 2 days max. It has dropped my phosphate down. The color test I have is useless at less than .25 which is now where I am.
I'm tempted to get that meter. I absolutely consider control of hair algae my number one concern. It about drove me out of saltwater. I only got rid of it by leaving the light off my fish only tank for two years. Now that I have light, its an issue. From what I read, phosphate control is key, a phosphate meter might be a good investment.
I have heard people say they have zero phosphate and still hair algae, though I'm not sure they are measuring with a meter.
I'm tempted to get that meter. I absolutely consider control of hair algae my number one concern. It about drove me out of saltwater. I only got rid of it by leaving the light off my fish only tank for two years. Now that I have light, its an issue. From what I read, phosphate control is key, a phosphate meter might be a good investment.
I have heard people say they have zero phosphate and still hair algae, though I'm not sure they are measuring with a meter.
I have been using Kent phosphate sponge but you can only have that in the filter for 2 days max.
Why? Just because it gets depleted?
Why? Just because it gets depleted?
Frogmanx82
New member
The instructions say it will start leaching phosphates back after two days. I think other element start knocking the phosphate out.
The manufacturer instructions say that?
FWIW, phosphate can come back of GFO as well.
FWIW, phosphate can come back of GFO as well.
The salfert test kit for phosphate does ok. The hanah colorimeter works quite well. I test obsessively, every day . The digital readout is nice. There is likely to always be some inorganic phosphate in the tank or being created from organic phopsphate at any given time. In my expeinece ,keeping it under .06ppm(hanah) limits nuisance algae to near none in my system
Frogmanx82
New member
From Kent Marine Phosphate Sponge
"Leave for 8 hours to 2 days maximum (as with any phosphate adsorber phosphates can be re-released into the system if the initial charge is left in the system continuously. If you want to leave in the system to keep phosphates low or to remove silicates, replace initial charge with brand new and change on a regular basis)."
They don't say what the regular basis is. I think if you really want to watch phosphates, the digital readout is a big help. I'm going to look into a good meter. Any suggestions beside Hanna?
"Leave for 8 hours to 2 days maximum (as with any phosphate adsorber phosphates can be re-released into the system if the initial charge is left in the system continuously. If you want to leave in the system to keep phosphates low or to remove silicates, replace initial charge with brand new and change on a regular basis)."
They don't say what the regular basis is. I think if you really want to watch phosphates, the digital readout is a big help. I'm going to look into a good meter. Any suggestions beside Hanna?
d0ughb0y
Active member
the 8 hours to 2 days seems about the same as that guy in the link that measured phosphate with a hanna meter hourly, after a couple days, the incremental change is very minimal, (I think even after replacing the GFO). So from that experiment, it seems to indicate GFO is good for about 2 days.
Milwaukee meter cost less than hanna.
I expect the same idea relates to both GFO and aluminum oxide: if you load it up with a lot of phosphate, then that phosphate can later come off under some conditions (I've shown that myself for GFO). If it has only a little phosphate on it, then it is a lot less likely to come off and still has capacity for more, regardless of the time factor.
d0ughb0y
Active member
just got the milwaukee phosphate meter today.
tested around 6pm
put GFO online then tested at midnight
I'll probably leave the GFO online for another day. I'm sure it will have capacity to absorb for weeks but the reactor is currently hanging in front of the tank.
tested around 6pm
put GFO online then tested at midnight
I'll probably leave the GFO online for another day. I'm sure it will have capacity to absorb for weeks but the reactor is currently hanging in front of the tank.
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Good to hear.
The top reading in the picture was before any GFO? That value of 0.05 ppm is not nearly as much of a concern as the 1 ppm you reported in the first post. GFO will last longer at these lower levels.
The top reading in the picture was before any GFO? That value of 0.05 ppm is not nearly as much of a concern as the 1 ppm you reported in the first post. GFO will last longer at these lower levels.
d0ughb0y
Active member
I am not the OP. This is the first time I used a meter. I have never got a reading other than zero using salifert po4 test kit. But I think it is a good guide for anyone using gfo to expect a significant drop in phosphate in a couple days or so (no need to go out and get one of these meters).
Frogmanx82
New member
I'm getting some of the high quality GFO and rox carbon from bulkreefsupply. I'm going to put the gfo in a canister. Will that GFO solidify on me? I read that I can mix the GFO with the carbon to avoid the problem. Is that my best option?
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