Regenerating GFO

[david00061]

Originally Posted by Randy Holmes-Farley

What is dilute hydrochloric acid (0.05 N?

Full strength muriatic acid (hydrochloric acid) from the hardware store is about 12 N. So you need to dilute it something like 1 part muriatic acid into 250 parts fresh or RO/DI water.

thanks

[david00061]

So, how much lye should i add to each soak? i want to regenerate 7 cups of GFO each time

[dkeller_nc]

Originally Posted by david00061

So, how much lye should i add to each soak? i want to regenerate 7 cups of GFO each time

A bit of a clarification - I stated above that I use a 2:1 ratio of NaOH solution to the volume of GFO to be regenerated. My actual usage is somewhat less than this - for 1 cup of GFO, I use enough NaOH solution to give me a total volume of 2 cups.

While I've never done any experimentation to prove it, I doubt the ratio is all that critical.

[david00061]

should gfo be rinse thoroughly with r/o between soaks

[bheron]

definitely. you can feel the sliminess when you first rinse it.

[FullBoreReefer]

Would something like this work?...

http://www.bulkapothecary.com/raw-in...FbTm7AodACEAXA

I have never done this the "regenerating" stuff but have been saving my gfo for a couple months in hopes to try it. Is there somewhere you would recommend getting it? Or cheaper(not that its expensive, but)?


Thanks!

[dja1980]

That might be a good find... I e-mailed Bulk Reef Supply a few months ago to see if they might be interested in offering this, but they said they had safety concerns. I don't know what their margin is on the HC GFO, but I would think they they could make the margin on Sodium Hydroxide even higher, and reefers would gladly purchase it due to savings compared to HC GFO. It seems like it would be a win-win for everyone, and they could even make one of the how-to videos on the subject. Oh well... maybe one day they'll change their mind. It would be nice to purchase this along with all my other bulk reef products from BRS.

[Randy Holmes-Farley]

Originally Posted by FullBoreReefer

Would something like this work?...

http://www.bulkapothecary.com/raw-in...FbTm7AodACEAXA

I have never done this the "regenerating" stuff but have been saving my gfo for a couple months in hopes to try it. Is there somewhere you would recommend getting it? Or cheaper(not that its expensive, but)?


Thanks!

That is a fine grade of sodium hydroxide for any reef use.

[FullBoreReefer]

My lye showed up today. Mixed up a liter to 1m, then added 4 cups of gfo and 8 cups solution into a container. Let the soaking begin...

[david00061]

I rinsed used GFO (7 cups) with tap water till pretty clean.
Nexted I soak with 15 cups of ro/di and a cap of Full strength muriatic acid (hydrochloric acid) for a few hours rinsed with ro/di.
I used a half of cup of lye and 15 cups of ro/di 7 cups of GFO let soak for 24 hours, stirring every once in a while. Rinse with ro/di. repeated 2 more times. Does this sound right?

After running GFO thru reactor for 24 hours I test tank water it is 0.15. I test water coming out of reactor it is 0.09. Does this sound like a good reduction of Phosphate? Or should it be reduced more?

[dkeller_nc]

Your regeneration procedure sounds about right, and your 1/2 cup of solid lye to 15 cups of RODI should make about 3.5 liters of approximately 1M NaOH. However, one thing you didn't mention is rinsing after the regeneration - it's essential that you get as much NaOH out of the GFO as reasonably possible. That might take as much as 10 rinses with RODI, as the GFO is porous and it takes a while for the NaOH solution in the pores to diffuse into the bulk solution so that it's removed by the rinses.

Adding a little bit of NaOH to your tank water by virtue of some being left in the GFO isn't a big deal, it will just boost your alkalinity a bit. But if a lot's left in the GFO, that might boost your alkalinity way more than you want.

From the standpoint of the in/out concentration measurements from your GFO reactor, your results sound OK. There's a lot of imprecision in phosphate tests, and whether all, most, or just a little of the incoming phosphate is absorbed depends on a lot of complex factors like particle size of the media, bed height of the media, and flowrate.

A better assessment is simply to measure your tank water's phosphate concentration over a few days. You should see a gradual downward trend followed by a leveling off. When the phosphate concentration begins to rise over a few day's measurements, it's time to change out the GFO.

[david00061]

I'm using BRS HC GFO I did rinse it 10 times. I'm using a 4" reactor. How much flow do you recommend? I have it so it just moves a little throughout the reactor

[dkeller_nc]

That's about right (just enough to move the GFO around a bit). Even if you've a particular setup with flow, reactor size, particle bed height, etc... that allows for a bit of phosphate to not be absorbed in one pass, that's not a problem.

Even with very modest flowrates, all of the tank's water's going to be processed through the reactor in a couple of hours, and so within a day or two the entire volume of the tank's water is going to be processed many times over (and so most if not all of the dissolved phosphate will be removed).

[elviraveloz]

Second time regenerating GFO and the particles turned an copper color. Should I use it?

[bertoni]

Hmm, I might give them an extra rinse, to see what happens. If you have a pH meter, you could check the pH of the rinse water, which might be interesting.

[elviraveloz]

It's 1000g. I left it overnight on 20 liters of RO/DI water 3 times already, being rinsing for four days already. I only have a high range PH reading solution, will that work?

[bertoni]

I wouldn't bother with the pH reading after that much rinsing. I suspect the GFO will be safe to use, although I'm not sure how much it'll adsorb anymore. I'd give it a shot.

[elviraveloz]

I use 190 grams of it yesterday, Phosphates before .07. Today reading is .02.

[bertoni]

Okay, that sounds like good progress!

[bheron]

i just did this again on a batch. this time didnt use my BRS GFO and instead simply soaked the GFO in a bucket with the solution for 4 days, occasionally stirring.

[elviraveloz]

Originally Posted by bertoni

I wouldn't bother with the pH reading after that much rinsing. I suspect the GFO will be safe to use, although I'm not sure how much it'll adsorb anymore. I'd give it a shot.

Like you anticipated, GFO only last a week, before regenerating use to last 3 weeks. I always keep it wet on original container. It may be Rowaphos brand it's not good brand for regeneration.

[bertoni]

Oh, well, another brand might be better for regeneration.

[bet77]

WTH? I can regen with 1 problem....... I can not get the media rinsed enough to get the PH below 10. In the beginning of the rinse the PH is nearly 11. I'm rinsing 4 cups of GFO at a time. Should I add some muratic acid to the rinse? Am I using too much LYE? Am I regenerating for too long?

[bertoni]

To Reef Central

The length of the regeneration is unimportant at the rinsing stage. How much water are you putting through the media? It's probably okay to use as is, but you could rinse a bit of vinegar through it, if you're worried. If you use muriatic acid, then I'd be careful about rinsing that out, and of course, handling muriatic acid is dangerous.

[tmz]

I don't check th pH;I just rinse it untill there is little to no soapy fell to it. I don't think a little extra alkalinity will have a significant effect.