Regenerating GFO

[SimonSKL]

So how are you folks handling the GFO to do the regen process? Are you removing it from the reactor and putting it in a bucket?

This is something I tried today, it's 2g of 0.1M NaOH solution recirculating through a BRS reactor. I figure I can just keep this unit as my "lye reactor" and rotate out the canister portion without ever needing to touch or remove the GFO. I have no idea how this will affect the acrylic or pump, but we'll see...

Matt, that's a pretty neat idea! I don't think at 0.1M, NaOH will do any harm to the pump and acrylic. You may need to add some fresh GFO to replace the portion that dissolved though.

 

[Matt_Wandell]

Thanks Simon!

This is working pretty good so far. I came in to find the flow had stopped yesterday morning due to back pressure from the media. I think this process may be creating lots of smaller fines, especially with the granular product. FWIW I am using BRS's granular regular quality GFO.

The upside is that the 0.1M NaOH doesn't appear to have any effect on the pump, rubber, or acrylic. I took the pump completely apart--looked good as new.

 

[Matt_Wandell]

1M NaOH has no apparent effect on a maxijet 1200 pump or BRS reactor after 4 days.

And for those reefers in the US looking for bulk NaOH sources, this is the cheapest I've found so far:
http://www.galladechem.com/

They sell 50# bags for $0.74 per pound, compared to $5.00-6.00 per pound for Roebic crystals. Another option is Rooto Drain Opener available from most ACE Hardwares. I've seen it priced from $2.50-4.00 per pound.


So a question for the chemistry experts out there:

Do you foresee any problems/benefits to using saltwater to do the regeneration, rather than DI or tap water?

Thanks,
Matt

 

[mike810]

im about to try to regenerate my GFO, I have about 3 cups of GFO. how much naoh should i use and how long should i soak it? Also, whats the best way to rinse out the gfo after this process? THANKS

 

[Matt_Wandell]

im about to try to regenerate my GFO, I have about 3 cups of GFO. how much naoh should i use and how long should i soak it? Also, whats the best way to rinse out the gfo after this process? THANKS

Based on our testing 12L of 1.0M NaOH (dissolve ~450g of 100% lye in 3 US gallons) will remove all the PO4 from that much GFO in about 96 hours. I should note that I used a reactor to soak it.

Using a reactor makes it easy to rinse too. Just add DI water to the input and send the output to drain. 20x the volume of GFO should be plenty.

 

[mike810]

if i rinse it in a reactor. can i use this very same reactor back on my tank including the pump?

 

[Matt_Wandell]

I don't see a problem with that. Just make sure you rinse it very well.

 

[mike810]

thanks for the info Matt

 

[sjfishguy]

Ok, I have basically read this entire thread over the course of a few weeks. I find all the measurements and times a little inconsistent and confusing. Can someone please write out exactly what to do with 1 CUP of GFO and the crystal NaOH (be sure to do 1 cup because they everyone will be able to tailor their amount from this). Exclude all the testing at different times, etc. I think enough people have done it now that the avg person doesnt need to test the PO4 coming off, we know its coming off. I think if someone could just type up a simple outline, with volumes and masses and times, it will make this thread much more effective and useful for people attempting to regenerate their GFO. Thanks so much!

 

[Der ABT]

So, I did some quick research on GFO regeneration. Two studies had some interesting info.

Second, under basic regeneration, a 15-40% loss in capacity is seen after the first regeneration cycle. It was posutulated by the authors that a phase transformation to geothite or hematite is occuring.
Scott

Oh man your bringing back memories, i used to make geothite with my wife (she did alot with soils) i will be making her read this tonight. and how do you say it-----Gertite---so few new this and when i say it right around chemistry people they all look at me with amazement--its a good step in with the coworkers
thanks for all the research guys, this is the fun side of chemistry, i never could get it....numbers/taxes are so much easier.

On the 8th page seems to be the best summary of what to do so far, i hope we can get a full step by step (i only got to the 8th page so forgive me if it was posted since then)

 

[tank41]

Im with you sjfishguy. This is a great thread. Just having a tuff time process it all. I have quite a bit of GFO that I have been saving and would love to try this. I have access to all the solutions needed but a outline would be great for us common Joes.
Thanks

 

[dja1980]

Yep... definitely some great info here, but I think there are several of us that would love to see some step-by-step instructions on the process.

 

[[17]shawn[17]]

Yep... definitely some great info here, but I think there are several of us that would love to see some step-by-step instructions on the process.

i second this, i have read through the whole thread and im unsure on exactly how to go about this, if someone could provide step-by step instructions that would be great!

 

[SimonSKL]

I am not sure I can summarize what have been posted in this thread but this is what I do to regenerate my GFO.

1. Use the hardest GFO you can find to reduce dissolution during the regeneration process. I use BRS HC GFO.
2. If I think there was calcium carbonate build-up on the GFO, I soaked it in 3% muriatic acid for about 24 hours. 1 part GFO to 6 parts 3% muriatic acid. (Note I don't do this step as I change my GFO monthly and I think I have very little buildup of calcium carbonate).
3. Rinse the GFO with RODI water a few times.
4. Soak the GFO with 0.5M NaOH (20g in 1 liter of water) for 5 days. 1 part GFO to 6 parts 0.5M NaOH. I stir the mixture once a day.
5. Rinse the GFO with RODI water a few times. Drain out excess water.
6. Store the wet GFO until used.

I am sure others have a different and better process or use vinegar or different concentrations of acid and NaOH but this has worked well for me. Thanks!

 

[tank41]

Thanks Simon. At what point do you use vinegar or is that optional or to be used instead of muriatic acid.
Thanks again this helps alot

 

[madmike]

vinegar or muriatic acid only needs to be used if there is calcium carbonate precipitation on the gfo. test a small amount and see if it fizzes, if so you need to do the presoak, if not you dont

I know I have a bunch of precip as my red gfo turns grey within a week or so in my system so I have to presoak with muriatic acid for a day before regen with NaOH

 

[tank41]

Can you clarify step #4. I just want to be clear. So If I have 1 cup of gfo i would submerge it in 6 cups of rooto (NaOh) but how much water for the NaOH. Is that 20 grams of NaOH per liter of water?
Thanks

 

[SimonSKL]

Can you clarify step #4. I just want to be clear. So If I have 1 cup of gfo i would submerge it in 6 cups of rooto (NaOh) but how much water for the NaOH. Is that 20 grams of NaOH per liter of water?
Thanks

The 1:6 ratio is minimum. The more NaOH you use, the better. Since you need at least 6 cups of NaOH, I would just go ahead and prepare 2 liters of 0.5M NaOH (dissolve 40g in 2 liters of RODI water) and put the one cup of GFO in it.

In other words, 1 cup GFO in 2 liters of RODI water with 40g of NaOH in it. Hope this helps.

 

[Matt_Wandell]

i second this, i have read through the whole thread and im unsure on exactly how to go about this, if someone could provide step-by step instructions that would be great!

I had the same concerns.

We're writing up an article based on the tests we've done that will be published soon in Advanced Aquarist, including step by step instructions.

 

[outy]

I would think that same mixture of lye and water can be used again to clean more GFO with a little touch up with more lye without having to thow it out all the time