Is it possible to actually have 0 phosphate in an older tank?

[Oregon Grown Reef]

I know this sounds crazy, but is it even possible to have 0 phosphates in a tank that's had the same rock for a few years? I bring this up because I know phosphate binds to rock, but after a couple of years it has to be saturated. I tested my tank yesterday with the Hanna Phosphorus ULR checker and it measured 0 phosphate, but I know that can't be right. I feed my tanks, like everyone else, so how is it that we get 0 readings for phosphate? My rock is mostly clear of algae, but there's still bubble algae on the rocks. Not a ton, but a few bubbles here and there. Is it possible to actually have 0 phosphate in an established tank? What explains the 0 reading?

 

[Saltyreef]

I know this sounds crazy, but is it even possible to have 0 phosphates in a tank that's had the same rock for a few years? I bring this up because I know phosphate binds to rock, but after a couple of years it has to be saturated. I tested my tank yesterday with the Hanna Phosphorus ULR checker and it measured 0 phosphate, but I know that can't be right. I feed my tanks, like everyone else, so how is it that we get 0 readings for phosphate? My rock is mostly clear of algae, but there's still bubble algae on the rocks. Not a ton, but a few bubbles here and there. Is it possible to actually have 0 phosphate in an established tank? What explains the 0 reading?

Your rocks could still be binding what little phosphate youve contributed over the 3 years.
Or, your nutrient export methods are working to the best of their ability.

Or, the bubble algae is feeding off the phosphate from the rocks before it becomes available to test for in the water column.

 

[tbrown]

I know this sounds crazy, but is it even possible to have 0 phosphates in a tank that's had the same rock for a few years? I bring this up because I know phosphate binds to rock, but after a couple of years it has to be saturated. I tested my tank yesterday with the Hanna Phosphorus ULR checker and it measured 0 phosphate, but I know that can't be right. I feed my tanks, like everyone else, so how is it that we get 0 readings for phosphate? My rock is mostly clear of algae, but there's still bubble algae on the rocks. Not a ton, but a few bubbles here and there. Is it possible to actually have 0 phosphate in an established tank? What explains the 0 reading?

What is your stocking levels? Do you have coral? Any macro algae? Do you run a skimmer? It is possible, as mentioned above, if your export is higher than your import. I know I have 12 smallish acro frags that eat phosphates. They're encrusting and starting to grow enough that in a 125 gallon tank I'm dropping 0.05 ppm of Phosphates per day and having to dose. This is in a year old tank with previously used rock. I skim very lightly 6 hours a day and have no macros - all coral uptake.

 

[Oregon Grown Reef]

Your rocks could still be binding what little phosphate youve contributed over the 3 years.
Or, your nutrient export methods are working to the best of their ability.

Or, the bubble algae is feeding off the phosphate from the rocks before it becomes available to test for in the water column.

The small amount of bubble algae wouldn't be enough IMO to bring it to zero, but obviously it does account for some of the uptake. I have an auto filter roller, a skimmer, and do 0.8 gallons, or 1.6% total volume, daily auto water change on a 50 gallon system. I only have 2 fish in there, 1 being a yellow eye kole tang and the other a six-line wrasse. There's a low input from fish, but I overfeed to compensate. Nitrate is at 4.1 as of today.

Edit: I should mention that the tank has had far more fish in it at times, but either from relocating them due to eating corals or to them dying, there are 2 now.

 

[Saltyreef]

The small amount of bubble algae wouldn't be enough IMO to bring it to zero, but obviously it does account for some of the uptake. I have an auto filter roller, a skimmer, and do 0.8 gallons, or 1.6% total volume, daily auto water change on a 50 gallon system. I only have 2 fish in there, 1 being a yellow eye kole tang and the other a six-line wrasse. There's a low input from fish, but I overfeed to compensate. Nitrate is at 4.1 as of today.

You never know. I had 0 phosphate with 10 year old USED liverock and no algae.
Had to start dosing potassium/sodium phosphate

 

[Saltyreef]

The auto filter rollers take out a lot of available decomposing food that turns to available phosphate in the watee column otherwise.

 

[Nano sapiens]

'True zero', as in absolutely no phosphate at all, quite unlikely. Not enough inorganic phosphate to measure with a test kit, sure.

My 12g nano has very rarely shown a PO4 reading (Salifert) in it's 14 years of operation (a Triton ICP test showed about 1/2 the levels of phosphate they recommend). IME, in a mature system it's largely how the corals look that is the best indicator of whether we are doing it right...or doing it wrong..

 

[Oregon Grown Reef]

'True zero', as in absolutely no phosphate at all, quite unlikely. Not enough inorganic phosphate to measure with a test kit, sure.

My 12g nano has very rarely shown a PO4 reading (Salifert) in it's 14 years of operation (a Triton ICP test showed about 1/2 the levels of phosphate they recommend). IME, in a mature system it's largely how the corals look that is the best indicator of whether we are doing it right...or doing it wrong..

This is what I was kind of thinking when I first posted this. If the corals look good, then phosphate surely can't actually be at 0. I still dosed a small amount of Brightwell Neophos, about 0.02 ppm, but I'm guessing it's not an actual problem.

 

[Saltyreef]

'True zero', as in absolutely no phosphate at all, quite unlikely. Not enough inorganic phosphate to measure with a test kit, sure.

My 12g nano has very rarely shown a PO4 reading (Salifert) in it's 14 years of operation (a Triton ICP test showed about 1/2 the levels of phosphate they recommend). IME, in a mature system it's largely how the corals look that is the best indicator of whether we are doing it right...or doing it wrong..

My reef ran the BEST with 0 measurable phosphate and near undetectable nitrates

 

[Oregon Grown Reef]

A little update. It turns out that having immeasurable phosphate is in fact bad. Lol big surprise. Everyone reading this just said no duh. No dead acros, but colors started fading and there is damaged tissue. I started dosing 0.02ppm daily since it was reading 0. Tissue recession stopped and color started returning. I'll continue to dose until there's no need.

 

[Saltyreef]

A little update. It turns out that having immeasurable phosphate is in fact bad. Lol big surprise. Everyone reading this just said no duh. No dead acros, but colors started fading and there is damaged tissue. I started dosing 0.02ppm daily since it was reading 0. Tissue recession stopped and color started returning. I'll continue to dose until there's no need.

I think I misspoke in my post with the .GIF

My reef ran the best with 0 measurable nitrate (salifert) and slightly elevated phosphate .01-.02 (red sea pro)

My bad and I hope you don't disown me as a brother and not invite me over for dinner next time I'm in town.......

 

[Saltyreef]

Also FWIW, the ocean runs at near undetecable nitrates and phosphates but those two nutrients are readily available in infinite near 0 amounts in the worlds oceans

 

[Randy Holmes-Farley]

Also FWIW, the ocean runs at near undetecable nitrates and phosphates but those two nutrients are readily available in infinite near 0 amounts in the worlds oceans

Perhaps more importantly, corals get N and P from particulate foods that are lacking in aquaria.

 

[Randy Holmes-Farley]

A little update. It turns out that having immeasurable phosphate is in fact bad. Lol big surprise. Everyone reading this just said no duh. No dead acros, but colors started fading and there is damaged tissue. I started dosing 0.02ppm daily since it was reading 0. Tissue recession stopped and color started returning. I'll continue to dose until there's no need.

I agree and never recommend less than 0.02 ppm phosphate.

Thanks for the update!

 

[tbrown]

A little update. It turns out that having immeasurable phosphate is in fact bad. Lol big surprise. Everyone reading this just said no duh. No dead acros, but colors started fading and there is damaged tissue. I started dosing 0.02ppm daily since it was reading 0. Tissue recession stopped and color started returning. I'll continue to dose until there's no need.

I went through the same thing. As soon as I started dosing tissue recession stopped and colors improved. I need to work on getting my nitrates down.