If phosphates level out does that mean rowaphos is exhausted?

[chris_pull]

Hi all,

I have just started using rowaphos to help get my phosphates to a level where I want them.

I added rowaphos to a high flow area in a media bag. After 24 hours, the phosphates went from 0.53 to 0.27 ppm (measured with Hanna ULR Phosphate checker). After 48 hours, the phosphates are sitting at 0.22. This could mean it's still binding phosphates though it may be that the rowaphos is exhausted already since the 0.05 decrease could just be error (I will measure again tomorrow).

I'd like to know if this means I should change out the rowaphos already? I used this online calculator (http://rowaphos-calculator.com) to work out that I needed ~70 ml of rowaphos for my 75-litre aquarium (double dose as it's not in a media reactor).

A media reactor isn't an option for me and so I know I won't get it to work super effectively.

Thanks a lot!

Chris

 

[Daddy-o]

If you were at .53 and now you have leveled out at .22 I would assume that the media is exhausted.
Cheers! Mark

 

[chris_pull]

If you were at .53 and now you have leveled out at .22 I would assume that the media is exhausted.
Cheers! Mark

Thanks! I didn't get around to changing it yet but has dropped a bit more to .17. I think this is still in the realm of measurement error but at least it's not going up!

 

[Randy Holmes-Farley Verified Community Expert]

It is certainly possible it is becoming depleted, but the more you try to remove, the harder it is and the longer it may take as phosphate comes off the rock and sand. Also, in a mech back, phosphate reaching the interior may take much longer than binding to the outmost GFO particles in the bag.

 

[chris_pull]

It is certainly possible it is becoming depleted, but the more you try to remove, the harder it is and the longer it may take as phosphate comes off the rock and sand. Also, in a mech back, phosphate reaching the interior may take much longer than binding to the outmost GFO particles in the bag.

I wondered about this: would it be worth to gently mix the GFO about in the bag so the interior is mixed up a bit?

 

[SPR1968]

It works much better in a reactor Chris and will probably last longer.

You did say it wasn’t an option, but you can get small ones and they can also sit outside the tank provided there sealed correctly

NYOS do a small one, the Torq 1.0 which is all self contained. Just an idea anyway.

I use a lot of rowaphos and once you get your levels very low, you learn how often to change it and I hardly ever test phosphate because I keep it locked down very low at less than 0.03.

 

[chris_pull]

Hi all – just an update, I've been switching out small bags of Rowaphos every four days or so, and today Hanna is reading .08 ppm, which is the first time it's gone sub .1!

I am aiming for about .03 ppm and wondered how Rowaphos works once you're at or near your target? I.e. how do you avoid going to 0? I imagine without a reactor my risk of this is low and I don't mind obviously if it goes a bit higher occasionally, but how do you use Rowaphos to maintain a fairly constant level? Is it a case of getting to .03 then testing and seeing if it's increasing and then replacing?

Thanks in advance for any tips!

Chris

 

[okayamapiper]

I know this is an old post, but I was wondering about fluidized bed reactors with GFO. As the GFO simmers in the reactor, does the depleted GFO surface containing iron phosphate rub off exposing unreacted GFO? Of course, this assumes that GFO is not porous so only the surface reacts with the ions in the water column. Any thoughts?

 

[Pavo]

Then a phosphates would stay in tank? Rubbed surface layer need to go somewhere and very fine dust is hard to keep inside reactor?

 

[Randy Holmes-Farley Verified Community Expert]

I know this is an old post, but I was wondering about fluidized bed reactors with GFO. As the GFO simmers in the reactor, does the depleted GFO surface containing iron phosphate rub off exposing unreacted GFO? Of course, this assumes that GFO is not porous so only the surface reacts with the ions in the water column. Any thoughts?

That is not the purpose. It may happen to a small extent, but is not the goal. The goal is to ensure that all of the GFO gets exposed and not just the outside of the GFO in a mesh bag, or the GFO that is near where the water channels through a fixed bed.

 

[Randy Holmes-Farley Verified Community Expert]

Then a phosphates would stay in tank? Rubbed surface layer need to go somewhere and very fine dust is hard to keep inside reactor?

Some iron oxide/phosphate may settle out in the tank, yes,. Same happens with lanthanum when using that. There is also lots of calcium phosphate present on the surfaces of calcium carbonate in most reef tanks.

 

[okayamapiper]

Then a phosphates would stay in tank? Rubbed surface layer need to go somewhere and very fine dust is hard to keep inside reactor?

Thank you for the information. I merely asked as was curious and with the price of GFO so high in Japan, I was trying to figure out a way to save some cash. I've used lanthanum but have found it does take a toll on the inhabitants if dosed directly.

 

[okayamapiper]

That is not the purpose. It may happen to a small extent, but is not the goal. The goal is to ensure that all of the GFO gets exposed and not just the outside of the GFO in a mesh bag, or the GFO that is near where the water channels through a fixed bed.

Thank you, Randy. I realize the fluidized bed reactor is mainly designed to ensure complete exposure to the media. I guess if it were the goal, there would be a large market for GFO dust as the increased surface would remove more phosphate, more quickly, but at the expense of a murky tank.

 

[Randy Holmes-Farley Verified Community Expert]

Thank you, Randy. I realize the fluidized bed reactor is mainly designed to ensure complete exposure to the media. I guess if it were the goal, there would be a large market for GFO dust as the increased surface would remove more phosphate, more quickly, but at the expense of a murky tank.

Some folks take this to the extreme, adding soluble iron to precipitate iron phosphate. I believe it is part of the DSR method.