Phosphate Help

[Kurtz]

I noticed for some reason my phosphates were elevated. 0.3 to be exact. That was so odd I had my LFS test it. Same result. All these parameters have been under control for over 6 months since I setup this tank. I did water changes and got the phosphates down to .07 last week. Tested it today a week later and it’s back at 0.26.

The only things I have changed recently in this tank other than adding a wrasse 3 months ago is I started the Phyto, Reef Enhance and Reed Energy AB+. I just don’t know what I am missing.

Help!

Waterbox AIO 20 Gal
Light: Kessil A80 Tuna Blue
Tunze Algea Reactor with chaeto

Dosing:
Amino Acids (4 drops) daily
Phyto (5ml) daily
Reef Enhance (half a scoop) 2x a week
Red Sea Reef Energy AB+ (2ml)
Benereef half a teaspoon 2x a week

I feed 1/4 of a cube of frozen brine shrimp a day


Peramiters:
Nitrate 0.500m
Phosphate: 0.26ppm
Calcium: 442ppm
Magnesium: 1500ppm
Alkalinity: 9.5dKH
Salinity: 1.025
PH: 7.9
Iodine: 0.06ppm

Lightning Schedule:
7:30 - 5 color / 5 intensity
8: 30c / 45i
10:00 - 55c / 80i
12:00 - 65c / 100i
15:00 - 65c / 100i
17:00 - 55c / 80i
18:30 - 30c / 45i
19:30 - 0c / 0i

 

[TexasReefer82]

Phosphate is adsorbed by calcium carbonate, ie all the rocks in your tank. It exists in our tanks in an equilibrium between the water and in the rocks.

When you did water changes to lower the concentration in the water you created what chemists call a deviation from equilibrium between the water and rocks. Some phosphate that was adsorbed on the rocks then desorbed into the water column to restore equilibrium. Your water has probably been at 0.26 for the entire week except for right after you did the water changes.

You'll need to continue removing phosphate from the water if the rocks are to desorb what they're holding. You could do this through more water changes. You could also decrease the input of phosphate to the water column and let consumption by corals and algae decrease the phosphate for you. You could also buy more Coral to help make this happen faster

 

[BobbyCline]

Water changes won't have much of an effect on phosphate levels...GFO will. I recently used it to drop my phosphate levels.

I was at 0.4 in my 80 gallon system. I used 8 tablespoons of GFO in a reactor, replaced every other day. In 10 days phosphate went from 0.4 to 0.01.

 

[Sean Duggan]

Agree on the GFO. You can use that or a similar product like phosguard. Since it’s an all in one tank you can get a media pouch and just toss a little bit into the back sump area.

 

[Kurtz]

Phosphate is adsorbed by calcium carbonate, ie all the rocks in your tank. It exists in our tanks in an equilibrium between the water and in the rocks.

When you did water changes to lower the concentration in the water you created what chemists call a deviation from equilibrium between the water and rocks. Some phosphate that was adsorbed on the rocks then desorbed into the water column to restore equilibrium. Your water has probably been at 0.26 for the entire week except for right after you did the water changes.

You'll need to continue removing phosphate from the water if the rocks are to desorb what they're holding. You could do this through more water changes. You could also decrease the input of phosphate to the water column and let consumption by corals and algae decrease the phosphate for you. You could also buy more Coral to help make this happen faster

I have a bag of Innovative Marine GFO I can drop in my filter sock.

 

[kevin_e]

Any alga?

 

[Kurtz]

Any Algea? No, rocks and sand are clean

 

[Brian_68]

Agree on the GFO. You can use that or a similar product like phosguard. Since it’s an all in one tank you can get a media pouch and just toss a little bit into the back sump area.

I used phosguard on a regular basis until my ICP test came back high Al then I stopped using it.

 

[kevin_e]

Any Algea? No, rocks and sand are clean

And corals have good coloration it seems. At least under blue lights. May not be an issue. May be faulty test? You could slowmy work it down with GFO, it's effective. Just be careful not to strip the water and bleach your coral.

Another option is lanthanum chloride. I've never used it, but I have some. Believe it drops by as much as 0.5 ppm per dose. Seems like more of an emergency option than for you.

Your tank seems fine with those phosphates. A lot of them are. Also, with your alk and calcoum that high, you may want to run higher phosphates and nitrates.

 

[TexasReefer82]

I wouldn't recommend using GFO. phosphate at 0.26 really isn't that high. Some SPS keepers maintain it at 0.2.

I'd slightly decrease your feeding of Coral foods and let it fall naturally over a couple weeks.

 

[Kurtz]

I wouldn't recommend using GFO. phosphate at 0.26 really isn't that high. Some SPS keepers maintain it at 0.2.

I'd slightly decrease your feeding of Coral foods and let it fall naturally over a couple weeks.

Does Benereef or Reef Enhance, Phyto increase phosphates, reef energy AB+? That’s the only thing I feed my corals.

 

[TexasReefer82]

Does Benereef or Reef Enhance, Phyto increase phosphates, reef energy AB+? That’s the only thing I feed my corals.

Phyto can... I'm not sure what product you are using for phyto.

One thing is for sure, Reef Roids is loaded with phosphorus. Those first two products look very similar to reef roids... I'd bet they're probably spiking your phosphates.

I only use reef roids on my reef once (occasionally twice) per week and at less than the suggested amount on the label.

 

[Shawn_epicurious]

I’ve been seeing this same idea about phosphate levels in quite a few threads. How the live rock absorbs and desorbs. I’m not sure I understand how “it” finds equilibrium? Does that mean if the phosphate level inside the rock is say... .05 and the water is at .07, then tomorrow the tank will measure .06? Have I got that right?

If so, then this sounds like over dosing? Or am I way off?

 

[TexasReefer82]

I’ve been seeing this same idea about phosphate levels in quite a few threads. How the live rock absorbs and desorbs. I’m not sure I understand how “it” finds equilibrium? Does that mean if the phosphate level inside the rock is say... .05 and the water is at .07, then tomorrow the tank will measure .06? Have I got that right?

If so, then this sounds like over dosing? Or am I way off?

Lemme try to explain this... And it's not just an idea, it's a solid chemistry fact, haha. GFO, which is also a rock, works the exact same way.

Let's start with something simple such as the chloride ion. Chloride has an interaction with water that allows it to be solvated and dissolved (as we normally think of it). However chloride doesn't interact with anything else like rock so all the chloride ions in your tank will be in the water column. Sodium the same.

The Phosphate ion however has an interaction with water as well as with calcium carbonate... As well as with ferric oxide (GFO) and likely several other minerals. It's via this interaction (not reaction) with CaCO3 that phosphate acts as a "crystal poison" to the growing surface of CaCO3 and can inhibit growth of our stony corals. Some of it adsorbs to the surface of CaCO3.

If you dump some phosphate into a tank containing both water and CaCO3 rock it will "partition" itself between the two spontaneously. A certain fraction will stay in the water and a certain fraction will adsorb to the rock. The amounts that are in both phases (aqueous and adsorbed) with always maintain a certain ratio between the two... This is called the "equilibrium constant " and the overall eq. Constant is specific to all the species involved (here water, CaCO3, and phosphate).

If you remove phosphate from the water, or add more, or add more clean rocks, whatever you do the phosphate will always partition itself to maintain the equilibrium constant. That's why water changes are a frustrating method of reducing high phosphate in a tank containing rock because the phosphate will repartition itself after the water change to maintain the equilibrium constant.

Phosphate also has an equilibrium constant with ferric oxide (gfo), however with this species the eq constant is far larger (or perhaps far smaller, I forget the math) such that between the water phase and the "adsorbed to gfo" phase the phosphate is virtually all partitioned onto the gfo and almost none in the water. This is why gfo is useful as a phosphate remover. The reverse can also happen, take phosphate loaded gfo and contact it with pure water and some will desorb into the water column... But only a small fraction of it, just to maintain the equilibrium constant.

 

[Shawn_epicurious]

Lemme try to explain this... And it's not just an idea, it's a solid chemistry fact, haha. GFO, which is also a rock, works the exact same way.

Let's start with something simple such as the chloride ion. Chloride has an interaction with water that allows it to be solvated and dissolved (as we normally think of it). However chloride doesn't interact with anything else like rock so all the chloride ions in your tank will be in the water column. Sodium the same.

The Phosphate ion however has an interaction with water as well as with calcium carbonate... As well as with ferric oxide (GFO) and likely several other minerals. It's via this interaction (not reaction) with CaCO3 that phosphate acts as a "crystal poison" to the growing surface of CaCO3 and can inhibit growth of our stony corals. Some of it adsorbs to the surface of CaCO3.

If you dump some phosphate into a tank containing both water and CaCO3 rock it will "partition" itself between the two spontaneously. A certain fraction will stay in the water and a certain fraction will adsorb to the rock. The amounts that are in both phases (aqueous and adsorbed) with always maintain a certain ratio between the two... This is called the "equilibrium constant " and the overall eq. Constant is specific to all the species involved (here water, CaCO3, and phosphate).

If you remove phosphate from the water, or add more, or add more clean rocks, whatever you do the phosphate will always partition itself to maintain the equilibrium constant. That's why water changes are a frustrating method of reducing high phosphate in a tank containing rock because the phosphate will repartition itself after the water change to maintain the equilibrium constant.

Phosphate also has an equilibrium constant with ferric oxide (gfo), however with this species the eq constant is far larger (or perhaps far smaller, I forget the math) such that between the water phase and the "adsorbed to gfo" phase the phosphate is virtually all partitioned onto the gfo and almost none in the water. This is why gfo is useful as a phosphate remover. The reverse can also happen, take phosphate loaded gfo and contact it with pure water and some will desorb into the water column... But only a small fraction of it, just to maintain the equilibrium constant.

Thanks for this. Really nice write up : ) I didn’t mean to reduce the science to a mere idea with my choice of vocabulary...

 

[TexasReefer82]

Thanks for this. Really nice write up : ) I didn’t mean to reduce the science to a mere idea with my choice of vocabulary...

Thank you! I didn't take it way. Was just trying to ensure that readers understood that what's happening with phosphate is well established chemistry.... They're not losing their minds, haha.

 

[Fishingandreefing]

Better watch out with gfo. I stripped some acros with only about 60% dosage.

 

[Shawn_epicurious]

Thank you! I didn't take it way. Was just trying to ensure that readers understood that what's happening with phosphate is well established chemistry.... They're not losing their minds, haha.

Phosphate is getting very close in my plan : ) I’m not dosing anything yet, but am gearing up for it.

 

[TexasReefer82]

Phosphate is getting very close in my plan : ) I’m not dosing anything yet, but am gearing up for it.

I've dosed phosphate to my reef over several stints of time. It works if that's what deficient. No doubt about it.

Currently I take a different approach and when phosphate gets too low I start feeding Reef Roids once or twice a week. Corals will use inorganic phosphate ("orthophosphate") just fine but they prefer organically bound phosphorus. Reef roids provides this and what's left over turns into orthophosphate.