Phosphate levels

[jda]

I like to be 2-4 on the Ultra Low. This gives me the best growth and the best color as far as crispness, bright/pop and best contrast. If I let it get from 10-20, the colors get darker/richer and contrast is less for multicolored stuff - growth is half of what it was when lower. Either way produces more color but of different kind, but I really like the contrasting acropora, so this works for me to keep it lower.

For example, I have a Atlantis Pink Granulosa - old school for those who were around. When the P is really low, the branches are light pink and the polyps are very dark/rich red. With the phosphate up a bit, the branches get darker pink and the tips get lighter too and the colony looks to be almost the same color.

To each their own with more/less color. I would probably be happy with either, TBH.

 

[Ocelaris]

Is 2-4, 0.2 to 0.4ppm or is that 2-4 ppb phosphorus?

Do you notice a trend of nuisance algae with higher phosphates?

 

[jda]

2-4 on the Hannah Ultra Low Test Kit. Sorry about that.

 

[bellasdad0911]

So after a few days of heavy feeding for my new blue jaw trigger to get acclimated and me being out of town for the U2 concert, I can home to a pretty dirty tank. Lots of algae on the glass and power heads but none anywhere else. So I figured nitrates and phosphates must have naturally climbed... so I did a full test out..

Phosphates 0
Nitrates 0
Salinity 1.025
Alk 8.5-9
Calcium 480

This boggles my mind, because since dosing the flourish phosphorus I had it all the way to .09 and yet after 2 days it's back to zero? And nitrates after some serious heavy feeding still zero? How can this be? My cap coral is pretty much gone and my forest fire that was thriving weeks ago is beyond stressed and receding where new growth occurred. So tonight I drained 10 gallons from my sump and replaced with new water and dosed stump grinder and the phosphorus again. I feel like something has been thrown way out of natural balance. Not sure how to get it back. I have never had this issue before. My skimmer oddly enough is pulling out plenty.

could it be exporting more than I am importing to keep the corals happy? Trying to find some answers. I am increasing feedings and I even just turned down the skimmer. I read that if phosphates and nitrates are out of balance this causes an algae outbreak?

 

[Ocelaris]

What other nutrient export methods do you use besides the skimmer? I couldn't keep phosphates up for the life of me with chaeto and an over sized skimmer. Now that my chaeto was pruned way back and my phosphates are around 0.4 I'm getting great color. I'm convinced now that phosphates are the hardest to keep up since they're so low to begin with.

 

[bellasdad0911]

What other nutrient export methods do you use besides the skimmer? I couldn't keep phosphates up for the life of me with chaeto and an over sized skimmer. Now that my chaeto was pruned way back and my phosphates are around 0.4 I'm getting great color. I'm convinced now that phosphates are the hardest to keep up since they're so low to begin with.

I only run the skimmer and use Red Sea reef carbon. I turned down the skimmer yesterday to hopefully keep up nitrates. I just don't want algae. I will have to text tonight to see where the levels are after 24 hours.

 

[jda]

This boggles my mind, because since dosing the flourish phosphorus I had it all the way to .09 and yet after 2 days it's back to zero? And nitrates after some serious heavy feeding still zero? How can this be?

A small amount was likely bound up by your inhabitants and the rest is very likely are binding to aragonite. Aragonite is very good at binding phosphates. This can become a problem if the aragonite binds too many for too long and becomes saturated.

 

[bellasdad0911]

A small amount was likely bound up by your inhabitants and the rest is very likely are binding to aragonite. Aragonite is very good at binding phosphates. This can become a problem if the aragonite binds too many for too long and becomes saturated.

That said, what is the he best course of action to counteract the swings? I feel as though once I balance this it should stay stable. Like I said I have never had this issue.

 

[jda]

I don't know. I don't dose phosphates and just let the tank handle them - aragonite and water changes. That has always been good enough for my acropora providing the best color and growth near NSW parameters. Low phosphates has never been an "issue" in my world, yet the end game.

Speaking only of aragonite binding, eventually it will fill/bind up and the levels will rise in the water. I would not be happy about this in my tanks, but you will have to get opinions from the people who want phosphates high. What normally happens is that the aragonite binds a small amount, then when you change water, they release some back to equilibrium with the water... almost like a buffer. The relationship is a bit more complex than "equilibrium" but that works for most discussions.

Is this a new tank? Most tanks have a bit bound up just from normal use where the Flourish might have gone up to .09 and then back down to .02 (or something), but not zero. New sand and fresh, phosphate free ocean live rock are capable of binding P to nothing. If the tank is new, then this will handle it's self on it's own.

 

[jda]

Do you have the Ultra Low Phosphorus Checker? It will likely show something.

 

[Ocelaris]

I have an ultra low phosphorus checker coming in tomorrow, so I hopefully can add some to the discussion. When my red sea kit registered zero, my corals suffered, even if I had 6ppm nitrates. So I am thinking some cases can occur where phosphates are being reduced quickly. My case was chaeto, trying to rid myself of algae, but the algae out competed the corals. I got the algae under control, but now I'm just try to hold on to some phosphates like bellasdad.

Do you have more details on the phosphates binding chemistry? I'm not very familiar with the phosphorus pathways as much as the nitrogen cycle.

 

[jda]

I don't have any links to articles on specific aragonite and phosphate binding in any great detail with strategy and suggestions, but aragonite will bind to all kinds of stuff including metals. There are some mentions of this in the Phosphate articles Dr. Holmes-Farley from a decade ago. There are also old RC threads in the archives where it is discussed. There is a lot of discussion around old-tank syndrome where people thought that their sand was releasing phosphates into the tank, when they actually just got fully bound and did not cover up bad husbandry anymore.

Bottom line is that the structure of aragonite will bind phosphate to "equilibrium" with the water - it is more complex than this, but this is good enough. It can get saturated. When the water gets high, the rocks bind more. When you change water or use some GFO and your tank P goes down, the aragonite will release some. In a heathy tank, the aragonite can act as a buffer of phosphate where it can keep the water column low until you change water the next time. In a poorly maintained tank, it can act as a seemingly never ending reservoir - have you seen people post that their tank went down big-time for P after some GFO just to have it go back up in a few days... this is aragonite releasing back to equilibrium.

IMO, this is one of the most fundamental pieces of reef chemistry and is also one of the least understood. I just shake my head when I see posts like "my P looks good, so I am not doing any water changes" when the folks don't know that the aragonite is filling up.

This is the best that I could come up with quickly... from this article http://www.advancedaquarist.com/2002/9/chemistry is this:

Likewise, phosphate can precipitate onto the surface of calcium carbonate, such as onto live rock and sand. The absorption of phosphate from seawater onto aragonite is pH dependent, with the maximum binding taking place around pH 8.4 and with less binding at lower and higher pH values. If the calcium carbonate crystal is static (not growing), then this process is reversible, and the aragonite can act as a reservoir for phosphate. This reservoir can make it difficult to completely remove excess phosphate from a tank that has experienced very high phosphate levels, and may permit algae to continue to thrive despite cutting off all external phosphate sources. In such cases, removal of the substrate may even be required.

The relationship of calcium carbonate to the phosphate cycle has been studied by Frank Millero in the Florida Bay ecosystem (click here for Millero's studies). If aragonite crystals are growing, as they often are in some parts of our systems, then I’d expect some of this phosphate to get buried and locked into the aragonite crystals.

A side effect of the adsorption of phosphate onto aragonite may well be the reported impact of phosphate on the calcification of corals. The presence of phosphate may inhibit the formation of calcium carbonate crystals via surface adsorption, and this effect may very well be the factor that inhibits calcification of corals at high phosphate levels.

Hope this helped a bit.

 

[jda]

If there is one thing that I want people to understand about this relationship, it is that sand is NOT your enemy... bad husbandry is (like always).

 

[Ocelaris]

Thanks, that's what I was looking for, guidelines to an understanding, I can do high school chemistry, but past that I need instructions. But this kind of jibes with what I'm seeing. I've been very diligent lately about stirring up the sand bed and water changes and I've seen my phosphates jump. But they're at a good level, so I'll keep up the husbandry. Thanks!

 

[bellasdad0911]

Tonight's levels, as you can see with the API ( ran out of salifert ) it shows either 10ppm or is it way higher from looking down? Phosphates dropped again from .09 to .04 as you can see. Thoughts? Is that really a night nitrate?

 

[TX_Punisher]

Hard to tell but certainly above 10. I'm shooting for less than 10 but my tank is onky 2 mos old. Might be time for some water changes.

 

[Ocelaris]

Surprised to see that my phosphates are around 0.16 according to the Hanna ulr kit, which explains some of the algae growth. I did test it in the morning though, and I normally test in the evening. It's been at 0.04 to 0.08 according to red and sea, so it's definitely worth it. But that explains why my colors are so good lately. I started the chaeto again, so we'll see how that does to naturally bring those levels down.

 

[Ocelaris]

So I tested again tonight and put a half cup of gfo in a bag in the filter sock. Red sea measured around 0.08 Hanna ulr measured somewhere around 0.12. So I'm not sure my earlier reading was spot on, as I'm still figuring out the Hanna meter, but does phosphate normally drop a significant amount during the day?

 

[Mattrg02]

So I tested again tonight and put a half cup of gfo in a bag in the filter sock. Red sea measured around 0.08 Hanna ulr measured somewhere around 0.12. So I'm not sure my earlier reading was spot on, as I'm still figuring out the Hanna meter, but does phosphate normally drop a significant amount during the day?

Mine does. I'll go from 0.04ppm to 0 in one day.

 

[Rakie]

Dose phosphates, dose nitrates. All is good, neither are bad for your corals. Don't listen to the 70's ULNS logic, those days are long dead.

My tank only has a skimmer for export, and the rock in the display. Nitrates can drop upwards of 5 overnight sometimes. I have my skimmer turned as low as possible, and dose to keep my nitrates around 20-25, phosphates around .08+