Help me understand something about nitrates and phosphates

[watchguy123]

I really like your question and the answers already given

there are both chemical and biological driven reactions going on effecting nitrate and phosphate levels

Chemicals are ones such as phosphate being bound up by aragonite or rockwork. Those chemical reactions go on till an equilibrium is reached and then increase or decrease depending on how much phosphate becomes available via food primarily (consumed or not).
Simultaneously, biological reactions are going on that will consume phosphates although apparently not all that efficiently. So all the live critters, like algae, fish, single and multicelled critters will all consume and/or utilize phosphates. The richer and larger biodiversity likely improves that uptake.
Nitrate levels are also effected by their chemical and biological reactions.

Physical export like water changes and skimming play a role as well. I am not sure that skimming plays much of a role in phosphate levels

The older a tank gets the more likely the chemical reactions have reached equilibrium. Also a likely
larger biodiversity and biomass has been achieved.

So in older tanks, feeding volume maintains the equilibrium. But for most tanks, it still takes a while for the nutrient levels to fluctuate with changes to feeding.

As with most things in life , a little bit is good but too much can be bad. I feel much more secure with measurable but “lower levels” of nutrients. I am concerned with unmeasurable levels because I think a lack of nutrients is a potential for unwanted pests like cyano outbreaks and dinos.

Plus as has been alluded in a previous post, most of what we “know” in reefing is what we have heard from others and may not be correct.

 

[Randy Holmes-Farley Verified Community Expert]

Alright, lets try this again. What would you recommend for increasing particulates? Seems the reef roids should be covering this shouldnt it?

I do not know what particulate foods are best. Corals may be very particular about both size/shape and the chemical nature of particulate foods, and what is eaten may depend on how fast it is flowing by and whether it can actively escape or not:

The effect of flow speed and food size on the capture efficiency and feeding behaviour of the cold-water coral Lophelia pertusa

The capture efficiency and feeding behaviour of the cold-water coral (CWC) Lophelia pertusa (Linnaeus, 1758) were investigated considering: (1) differ…

www.sciencedirect.com

" In conclusion, flow speeds clearly impact food capture efficiency in L. pertusa, with zooplankton predominantly captured prey at low flow velocities (2 cm s− 1) and phytoplankton captured at higher flow velocities of 5 cm s− 1."

 

[reef_ninja]

I really like your question and the answers already given

there are both chemical and biological driven reactions going on effecting nitrate and phosphate levels

Chemicals are ones such as phosphate being bound up by aragonite or rockwork. Those chemical reactions go on till an equilibrium is reached and then increase or decrease depending on how much phosphate becomes available via food primarily (consumed or not).
Simultaneously, biological reactions are going on that will consume phosphates although apparently not all that efficiently. So all the live critters, like algae, fish, single and multicelled critters will all consume and/or utilize phosphates. The richer and larger biodiversity likely improves that uptake.
Nitrate levels are also effected by their chemical and biological reactions.

Physical export like water changes and skimming play a role as well. I am not sure that skimming plays much of a role in phosphate levels

The older a tank gets the more likely the chemical reactions have reached equilibrium. Also a likely
larger biodiversity and biomass has been achieved.

So in older tanks, feeding volume maintains the equilibrium. But for most tanks, it still takes a while for the nutrient levels to fluctuate with changes to feeding.

As with most things in life , a little bit is good but too much can be bad. I feel much more secure with measurable but “lower levels” of nutrients. I am concerned with unmeasurable levels because I think a lack of nutrients is a potential for unwanted pests like cyano outbreaks and dinos.

Plus as has been alluded in a previous post, most of what we “know” in reefing is what we have heard from others and may not be correct.

I agree, I think its a good discussion as well.

One thing I'm seeing that I need to clarify for myself, is whether I'm looking at nitrates and phosphates too narrowly. Currently, I'm addressing it as, well, nitrates and phosphates are low, so Ill dose some sodium nitrate and sodium phosphate.

Im seeing that the value of measurable phosphate and nitrate isn't just in the numbers of po4 and no3, but that those numbers indicate the measure of a bigger process, or lack thereof. Its trying to address that bigger process that's getting to me. Maybe Im skimming too much, maybe I need more of a bioload, maybe I need to add amino acids. Who knows, but I like what the discussion has added.

 

[Randy Holmes-Farley Verified Community Expert]

Keeping nitrate and phosphate at reasonable levels is the easiest thing to control since they can be dosed and measured.

Other sources of N and P cannot be measured, so even if you add them, you, or someone else, needs to determine how much is good based on observation of the corals.

 

[b.clark]

Reef ninja
Do you buy from a local pet store. If so, does their tank, corals, and fish look good. If you like what you see and are buying from them test their water. When you buy a coral bring it home and don’t pour out the water. Test it and see what their numbers are and try to mimic their numbers. My local shop writes there numbers on the front of their systems. Their corals always look good and grow good. If someone else test my water I always try to have the same person check it so it’s always tested and read the same way. Every person test and reads test a little differently

 

[reef_ninja]

Reef ninja
Do you buy from a local pet store. If so, does their tank, corals, and fish look good. If you like what you see and are buying from them test their water. When you buy a coral bring it home and don’t pour out the water. Test it and see what their numbers are and try to mimic their numbers. My local shop writes there numbers on the front of their systems. Their corals always look good and grow good. If someone else test my water I always try to have the same person check it so it’s always tested and read the same way. Every person test and reads test a little differently

We do, but I dont make it up there very often. Im heading up there this week to tap their shoulders too. Some of their displays, especially the ones they dont sell from, are very nice and healthy.

 

[reef_ninja]

Keeping nitrate and phosphate at reasonable levels is the easiest thing to control since they can be dosed and measured.

Other sources of N and P cannot be measured, so even if you add them, you, or someone else, needs to determine how much is good based on observation of the corals.

Ill keep dosing as I have been, just wondering if I should be looking at something else too.

 

[reef_ninja]

Can someone shed some light on particulate foods? What are they and what are some examples?

 

[Randy Holmes-Farley Verified Community Expert]

Can someone shed some light on particulate foods? What are they and what are some examples?

The primary natural ones are living organisms that corals and sponges and other organisms eat: bacteria, zooplankton, and phytoplankton.

 

[Thaxxx]

I would say get more fish.
4 small fish in a 40gal. tank isn't making too much waste. Overfeeding is one thing, but getting more fish to feed your corals is a good thing. Maybe you can stop dosing if you increase your fish load.

 

[reef_ninja]

I would say get more fish.
4 small fish in a 40gal. tank isn't making too much waste. Overfeeding is one thing, but getting more fish to feed your corals is a good thing. Maybe you can stop dosing if you increase your fish load.

Good point, I’m thinking this as well. The problem is my current fish, one of which is a maroon and she’s a big bruiser. But I’m finding her a new home, and that’ll make more room for more fish.

 

[ScottB]

Good point, I’m thinking this as well. The problem is my current fish, one of which is a maroon and she’s a big bruiser. But I’m finding her a new home, and that’ll make more room for more fish.

I think you are on the right track there. Adding some fish load is the most natural source of boosting useful nutrient. The fish are constantly respiring ammonia into the water column. I keep my frag systems LOADED with big fat fish.

 

[92Miata]

If you look at old tank of the months (2000) they all mostly had metal halides/t5s and 0/0 for no3 and po4. They also mostly used powerful protein skimmers. Also had deep sand beds. Id suspect as long as there are a slow increase in nutrients but its consumed fast enough, im there shouldn't be an increase.

Most of these tanks were 'undetectable' - not zero. Tests are way more precise now.


Modern protein skimmers work way better than skimmers from that time period. I ran an 8" bodied skimmer with a 150w pump on it back in the early 2000s on my 65. Most of today's skimmers would outperform it.

Flow is way better now.

And people back then didn't have this ridiculous obsession with clean/sterile reef tanks. They had real live rock, and they fed copious amounts of food.


Corals don't need readable nitrate/Phosphate. They need them to be available. Feeding more and skimming more works better than dosing to maintain high ambient.

 

[reef_ninja]

Most of these tanks were 'undetectable' - not zero. Tests are way more precise now.


Modern protein skimmers work way better than skimmers from that time period. I ran an 8" bodied skimmer with a 150w pump on it back in the early 2000s on my 65. Most of today's skimmers would outperform it.

Flow is way better now.

And people back then didn't have this ridiculous obsession with clean/sterile reef tanks. They had real live rock, and they fed copious amounts of food.


Corals don't need readable nitrate/Phosphate. They need them to be available. Feeding more and skimming more works better than dosing to maintain high ambient.

Hmm. But I am feeding more and skimming more. The skimmer I’m running now is quite efficient, and I’m feeding heavily 2-3 times a day, but that isn’t working. Cant argue the value of readable nitrates and phosphates, as my experience is still fresh with this. But I’ve been feeding heavily for 4 months now and things aren’t getting better

 

[saltyfins]

If you have algae, then you aren't a solid 0 on your nutrients. So here's what MIGHT be happening:

You algae is consuming nutrients at the rate they are being produced, which will give you a 0 test reading.
Another possibility is that your rocks are absorbing phosphate. At some point they will become saturated and start to release it back into the water. I know this happens with dry rock, not sure if it can happen with live rock.

One of the things I've learned in my 20+ years of reefing is to use a lot of the advice I find as great guidelines or starting points. Every system is different, and I've seen tanks flourish under conditions many reefers would consider a death sentence! Use what works for your tank.

this may be a really dumb question...but I'm going to ask it anyway. how exactly, do rocks absorb anything? I think sponge...when I hear that word..

 

[92Miata]

Hmm. But I am feeding more and skimming more. The skimmer I’m running now is quite efficient, and I’m feeding heavily 2-3 times a day, but that isn’t working. Cant argue the value of readable nitrates and phosphates, as my experience is still fresh with this. But I’ve been feeding heavily for 4 months now and things aren’t getting better

Corals need access to nitrogen and Phosphorus.

They prefer ammonia to nitrate (which is why nitrate dosing is a little strange).

Fish act as slow-release Phosphorus/nitrogen dispensers. They turn nutrient surges (feeding) into a slower more constant available form. They pretty constantly release ammonia through their gills and every time they poop, you get a little burst of Phosphate.

Ideally what you want is low ambient levels with high availability. More feeding, and more fish will both increase availability. This is what the ocean is like - levels are low, but there's constantly new water - so they can't be depleted.

Skimming less will both increase availability and ambient - so more feeding/input is generally preferable - but some tanks seem to be really efficient at removing Phosphate/ammonia from the water - and in those cases there's nothing wrong with skimming less and having higher ambient levels.

Don't worry about numbers too much, or what the 'right' thing is - worry about what works for your tank. They're all different.

 

[T-J]

this may be a really dumb question...but I'm going to ask it anyway. how exactly, do rocks absorb anything? I think sponge...when I hear that word..

Per another post by Randy Holmes-Farley: "..phosphate is attracted to calcium carbonate surfaces just like it is to GFO. It binds chemically. The amount binding depends on the pH and on the phosphate present in the tank water (and, or course, the available surface area of calcium carbonate)."

 

[ScottB]

this may be a really dumb question...but I'm going to ask it anyway. how exactly, do rocks absorb anything? I think sponge...when I hear that word..

Rocks are made of aragonite. Aragonite binds or absorbs phosphorus. Your rock can hold A LOT of phosphorus. As long as the rock is less saturated than the water, it will continue to absorb. Once the rock is more saturated than the water, it will release phosphorus back to the water.

 

[Randy Holmes-Farley Verified Community Expert]

this may be a really dumb question...but I'm going to ask it anyway. how exactly, do rocks absorb anything? I think sponge...when I hear that word..

As folks have noted, it is binding to the exposed surface, replacing carbonate on the calcium carbonate surface with phosphate, forming a thin layer of calcium phosphate. Magneisum also binds.

These two, along with organics, are the main reason that alk and calcium do not crash out on the exposed calcium carbonate surfaced despite seawater being supersaturated with respect to calcium and carbonate. They interfere with calcium carbonate precipitation by blocking it.

 

[beesnreefs]

Following as I'm going through a similar journey