[karnivor]

Most reefers fight a constant battle with Phosphates, in an attempt to control Algae and Cyano.

However products used for the removal of Phosphates are steadily getting better and improved water management is also helping.

It is possible to now get phosphate levels extremely low and it poses the question " how low is too low"?

Could we actually reach a point of damaging our corals or negatively affect growth by dragging Phosphates down to trace levels?

What would the benefits of such low levels be?

Is there a target we should be aiming for and does it bear any resemblance to NSW levels?


Lets debate the issue here, and post up any useful links to any research on the subject.

Over to you.

Tony.

[lindsay]

Ok,ile go first lol,i aim for around 0.008 to 0.015 mgl p or put another way 0.024 to 0.046 mgl po4,below this and in the past i have found sps and lps don't look as good and can start to show loss of colour and when going too low suffer die back around the bases of sps.Funny enough i struggle to keep the sps system above 0.008 mgl p but get around it by two coral and fish feeds a day.
For me i think that around 0.008 mgl p ish is low enough for most systems and to go lower could in-fact do more harm than good.

[chriss]

I'm going to refrain from commenting, he's a tricky beggar is this karnivor, never asks without having something up his sleeve.

Chris

[karnivor]

Cor, talk about P1$$1NG on my bonfire!!

Nope, nothing devious about it at all. I'm genuinely interested in peoples opinions. I have a good couple of links that I will be posting up, but didnt want to influence anyone's thinking by doing it too early.

I'm pretty well where Lindsay is with my thinking. I like to hover around .0007 PPM Phosphorus but would be prepared to go lower on an experimental basis.

One interesting aspect is that if we accept this as the correct level (and i'm not saying it is) then reading and maintaining phosphates so low becomes a problem as test kits and even electronic kits are at their lowest readings. My hanna kit for instance will only read either .01 PO4 or .02 PO4. gien that you can expect a 1 digit inaccuracy on the meter, you could be 100% out.

It is for that reason that I have ordered the new Hanna Phosphorus meter which measures in Phosphorous down to PPB's.

All this has led me to ask the OP questions.

Now come on guys, lets make a debate out of it.

[chriss]

Ok then. I think I'm happy with the results I get with the basic salifert kit when it is colourless. Whatever this really equates to, I don't know but I'm dubious how going much lower would make a world of difference. Of course I'd be only to pleased to be shown the errors of my way.

The price of the Hanna kit makes it very attractive but at the risk of encouraging you to chase ever lower figures.

Chris

[lindsay]

The other thing is when you get down to very low levels you need to be able to trust the kit that you are testing with so you can avoid going too low,if there is such a thing as too low.Perhaps a good idea on this thread would be for people to put what their levels are on what test kit and how their tanks corals look at the level of phosphates they have?.

[mrfishy]

i'm running a pellet reactor and rowa reactor, my nitrates and phosphates are getting undetectable on my hanna kit, what will be the first signs of going too low?.
Quite surprised there hasn't been more interest on this thread

[lindsay]

You may see paling of some of the sps,ie colours not as deep and rich as you have now,if phos and nitrates get very low then slow base recession is a possibility.

[TrevC]

I put my thoughts on the thread for the Hannah Test Meter.....


Bought one of these last month along with the 25 extra sachets, and have to say it's easy to use and there is no confusion over the reading.
No more trying to guess with the Salifert kit.

Took it to Jason’s for a chat with Linds......

My tank had measured 0.00, as did the SPS tank at Jason’s.

Then Linds asked the all important question....

"How accurate is it?"

Looking at the bumf that comes with it revealed + or - 0.04 ppm, + or - 4% of reading @ 25 C.

So a reading of 0.00 could actually be between 0.00 and 0.0416.

Sounds a bit high!

The Salifert test is difficult to read at or below 0.03 ppm, in fact unless you have super sensitive eyes it's difficult until you get to 0.1 !

We then had a look at the D & D test kit. There are 2 different scales here, one measure Phosphate PO4 (the larger numbers, bottom row) and the other measures Phosphate-Phosphor (top row).

The D & D kit also quotes mg/l....not to worry it's a simple 1:1 to conversion to ppm (unless you go down to 6 decimal places tongue.gif )

Big thing to keep in mind here is that the phosphate-phosphor test is about 1/3 the reading of the phosphate test (same as the Salifert test kit).

The Hannah tests for PO4 so a reading of 0.0416 ppm equates to 0.01386 ppm of Phosphate-phosphor.


Moving on we then tested the LPS system which read 0.02 ppm with the Hannah.
Equates to 0.00666 of phosphate-phosphor.
It was actually possible to see a hint of blue in the test vial.

Not being a Chemist, and it's been quite a few years since setting fire to the gas taps in a chemistry lab......

What is the relationship between phosphate (PO4) and phosphate-phosphor (PO4-P)????

[lindsay]

Ive not had time to look up the two,Po4 and Po4 P,has anyone else?.

[karnivor]

PO4 is phosphate, whereas PO4-P is the phosphorous content.
Generally, we talk about phospates(PO4) but are actually referring to Phosphorous levels (PO4-P) Its is expressed as PO4-P because while it normally exists as Phosphate or Orthophosphate, it is the Phosphorous within the PO4 that we are measuring.

You can directly convert between the two. 1ppm Phosphorous (PO4-P) = 3.065 ppm Phosphate (PO4). multiplication by 3 is plenty accurate enough though.

[chriss]

TrevC, on Jun 15 2010, 06:28 PM, said:

I put my thoughts on the thread for the Hannah Test Meter.....


Bought one of these last month along with the 25 extra sachets, and have to say it's easy to use and there is no confusion over the reading.
No more trying to guess with the Salifert kit.

Took it to Jason’s for a chat with Linds......

My tank had measured 0.00, as did the SPS tank at Jason’s.

Then Linds asked the all important question....

"How accurate is it?"

Looking at the bumf that comes with it revealed + or - 0.04 ppm, + or - 4% of reading @ 25 C.

So a reading of 0.00 could actually be between 0.00 and 0.0416.

Sounds a bit high!

The Salifert test is difficult to read at or below 0.03 ppm, in fact unless you have super sensitive eyes it's difficult until you get to 0.1 !

We then had a look at the D & D test kit. There are 2 different scales here, one measure Phosphate PO4 (the larger numbers, bottom row) and the other measures Phosphate-Phosphor (top row).

The D & D kit also quotes mg/l....not to worry it's a simple 1:1 to conversion to ppm (unless you go down to 6 decimal places tongue.gif )

Big thing to keep in mind here is that the phosphate-phosphor test is about 1/3 the reading of the phosphate test (same as the Salifert test kit).

The Hannah tests for PO4 so a reading of 0.0416 ppm equates to 0.01386 ppm of Phosphate-phosphor.


Moving on we then tested the LPS system which read 0.02 ppm with the Hannah.
Equates to 0.00666 of phosphate-phosphor.
It was actually possible to see a hint of blue in the test vial.

Not being a Chemist, and it's been quite a few years since setting fire to the gas taps in a chemistry lab......

What is the relationship between phosphate (PO4) and phosphate-phosphor (PO4-P)????

Does that mean the electronic tester isn't really anymore accurate for us than the traditional one?

Further more, if the traditional one reads zero to the eye, isn't that low enough?

Chris

[TrevC]

chriss, on Jun 20 2010, 04:28 PM, said:

Does that mean the electronic tester isn't really anymore accurate for us than the traditional one?

Further more, if the traditional one reads zero to the eye, isn't that low enough?

Chris

Well Chris, that all depends if you can actually discern the colour changes of the test kit you are using.

If you use the Salifert one can you honestly tell if you have between 0 to 0.03 ppm? (PO4)

If you use the D & D one this equates to 0.01 mg/l PO4-P.

My point was really....it doesn't matter which test kit or tester you use.

It matters that you trust what you are either seeing or being told by the kit/tester.

They all seem to give a fairly accurate indication of PO4 in your tank.

After all "How low is too low?"

[karnivor]

This link may help to answer that question.

http://www.wetwebmedia.com/ca/volume_5/vol.../phosphates.htm

Tony.

[TrevC]

Read that before and thought that the comment on "Control" was perfect!

[bobba fett]

I would just be happy if like Chris I could get colourless on a Salifert kit

[Marcus Watts]

yes, me too, getting colourless would be great. when that day arrives i'll get a better test kit but all the time salifert shows it up there's no real need. Now the tank is leaning towards keeping sps properly i'm having a blitz on phos, as when it was lps dominated I left the levels quite high (0.5). this just seemed to be the tanks natural level, running no phos remover and feeding heavy etc.

reading the article tony linked to was interesting, i'll be rinsing off commercially bought frozen foods now for sure. I've just put a pot of remover in a spare phosban reactor that was too small for the biopellets, plugged it up with filter floss though as the last time i used it all the stuff worked its way out into the sump

[karnivor]

This puts the cat among the pigeons.

Discuss.

http://reefbuilders....osphate-growth/

[lindsay]

Wow,goes to show how they can cope with higher levels than most are prepared to alow a system to reach.I have got to say that although impressive reading it does not surprise me because i have taken in sps that have lived in similar levels that have been ok showing not just good growth but depending on species great colour.That said one thing i have noticed is that when the level of phosphate gets high enough to stop the growth you will likely see the tips of sps look like E Ts fingers,ie they will have what looks like round blobs on the ends where the growth has stopped yet the same acro appeared ok other than this,have seen this a few times over the years.
Do you also think that for a coral to use higher nutrient levels it would need lighting to match,ie if the above experiment was done under say t5 lighting and not halides the coral would struggle to accommodate the extra zoox without being overwhelmed?.That said i don't remember reading what the lighting was in the experiments,better take another look lol.
Good find and i hope there will be more comments on it from others.