Desorbing phosphate from sand with lanthanum.

[Garf]

Along with phosphate and yellowing compounds, I'm wondering if I'm removing other things when regenerating this sand. Iodate, iron, manganese perhaps? Any insight @taricha @Randy Holmes-Farley please. Tank phosphate now at 0.2ppm (Hanna)

 

[taricha]

If you remove significant yellowing compounds, you are removing some iron.
On GFO, PO4 and Si both attach to the sites, so I'd guess Si might also attach a bit to aragonite too.

 

[Randy Holmes-Farley]

Iodate won't bind to calcium carbonate surfaces. Iron and manganese may.

 

[Randy Holmes-Farley]

If you remove significant yellowing compounds, you are removing some iron.
On GFO, PO4 and Si both attach to the sites, so I'd guess Si might also attach a bit to aragonite too.

Couldn't the yellowing be organics?

 

[taricha]

Couldn't the yellowing be organics?

Right. Yellow organics in tank water has an absorbance/fluorescence profile that's a pretty good match for what's measured in marine humic substances. So I'm expecting some part of our yellow compounds also likes to grab Fe.

 

[Randy Holmes-Farley]

Right. Yellow organics in tank water has an absorbance/fluorescence profile that's a pretty good match for what's measured in marine humic substances. So I'm expecting some part of our yellow compounds also likes to grab Fe.

Ah, OK, I thought since you meant that iron was itself causing the color.

 

[Garf]

Tank phosphate now at 0.15, nitrate at 10ish (salifert). I'll add a pic of the regeneration bucket after giving the regenerated sand a dang good massage;

Edit - I would add that nitrates have taken a nose dive since adding manganese, iodine and iron. Related? I am adding a little more vinegar in my kalk now, however. Maybe still related? Another edit - and double the amount of sand, lol.

 

[Dburr1014]

Tank phosphate now at 0.15, nitrate at 10ish (salifert). I'll add a pic of the regeneration bucket after giving the regenerated sand a dang good massage;

Edit - I would add that nitrates have taken a nose dive since adding manganese, iodine and iron. Related? I am adding a little more vinegar in my kalk now, however. Maybe still related? Another edit - and double the amount of sand, lol.

@Garf are you still doing this test?

I have run into a rapid po4 climb myself and I'm thinking it might be because I removed about 15ish lbs of arragonite sand from my system. (not sure exactly on weight) in the past month I went from 0.1ish (forever ran there) to 3.8 today. Last Monday it was 2.8
I first thought testing error but now I don't think so. I'm using a Hanna tester.
The only other change in my system is dosing ammonium chloride as I was zero nitrates since last May. Now I'm about 7.9 days the Hanna tester. It was up to 11pm and I was getting some funky green floating algae in the sump. Actually, I think it was some form of cyanobacteria. I dialed back the AC dose and the cyano is subsiding.
I'm thinking I may put the sand back in and see if po4 drops again. It was basically a remote dsb in the refuge at about 5 inches deep.
I'm finding this type of po4 reduction pretty interesting.

 

[Garf]

@Garf are you still doing this test?

I have run into a rapid po4 climb myself and I'm thinking it might be because I removed about 15ish lbs of arragonite sand from my system. (not sure exactly on weight) in the past month I went from 0.1ish (forever ran there) to 3.8 today. Last Monday it was 2.8
I first thought testing error but now I don't think so. I'm using a Hanna tester.
The only other change in my system is dosing ammonium chloride as I was zero nitrates since last May. Now I'm about 7.9 days the Hanna tester. It was up to 11pm and I was getting some funky green floating algae in the sump. Actually, I think it was some form of cyanobacteria. I dialed back the AC dose and the cyano is subsiding.
I'm thinking I may put the sand back in and see if po4 drops again. It was basically a remote dsb in the refuge.
I'm finding this type of po4 reduction pretty interesting.

Yes, this is the method I'm sticking with, works well for me. Started doing it in the wife's tank also. I would add that in a tank with loads of sand already in the system, progress maybe painfully slow due to the amount of phosphate already bound to that sand.

in the past month I went from 0.1ish (forever ran there) to 3.8 today. Last Monday it was 2.8

Sounds a bit odd. Remote deep sand beds are generally for nitrate control as the sand is left in situ for prolonged periods. I can't think of any process that would increase your phosphates like that, apart from dumping loads of food in, or a phosphate solution, sorry.

 

[Dburr1014]

Sounds a bit odd. Remote deep sand beds are generally for nitrate control as the sand is left in situ for prolonged periods. I can't think of any process that would increase your phosphates like that, apart from dumping loads of food in, or a phosphate solution, sorry.

I did have a auto feeder on the system feeding flakes 4 times a day. I have since removed that. I realize that the sand is for nitrate control and I was trying to get rid of mine. I thought that maybe the sand was also reducing phosphates a little bit. I also tested a new batch of salt water thinking it was in my well, that was 0.02 on the Hanna.
I can't think of anywhere else it's coming from.