phosphates

[tang]

Think a little more about those sudden and unexplained algae outbreaks that hobbyists report. They report these outbreaks even though in the instances when they occur testing would seem to indicate that all water quality chemistry parameters (especially phosphates) are extremely low (P04 < 0.04 ppm) and within recommended ranges, a set of circumstances where micro algae should NOT grow.

Such low phosphate concentrations, and the fact that other water quality parameters are completely in line with generally recommended safe levels, should not give rise to the appearance of micro algae at all. Yet, hobbyists report that they, nevertheless, happen and often occur suddenly, at the most unexpected time. This is happening to experienced hobbyists and beginners alike. Everybody is, needless to say, stumped when this befalls him or her, even the experts.

This being the case, why do these micro algae suddenly appear even though tank conditions and water quality do not account for such growth at all? It has been postulated and even proven that the long-term use of Kalkwasser precipitates phosphates out of the water (which Kalkwasser really does) and that these phosphate based compounds settle on and in the live rock in the aquarium, as well as in and on the substrate that may be present in the aquarium.

Since these compounds are not soluble at the high pH levels, they are really not a cause for concern, because in their insoluble state, they are not available as nutrients for uptake by micro algae and the growth of the same. Over time they simply accumulate more and more in the tank as insoluble matter; which can, by the way, be siphoned out from time to time (not weekly, not monthly, but perhaps every six months or so). Insoluble matter is of no concern, since it cannot affect tank conditions. In its insoluble state, it is also inert and does not react in any way with the water in the aquarium. In this state, it certainly cannot provide nutrients for micro algae to grow profusely in some reported cases.

Apparently, situations can, and may, however, occur whereby certain areas of the tank actually exhibit a different pH level than the one measured in the main body of water in the aquarium. In this instance, "different" means lower, and sometimes quite a bit lower, than the aquarium's pH level.

Where would this occur and why? Can this, in fact, occur at all? The answer is yes in all cases demonstrated by empirical evidence that such micro algae outbreaks do occur (the reports by the hobbyists). They may not be the norm, but they happen frequently enough to be a cause of concern. Many hobbyists who report that such sudden growths have happened to them even though they have adhered to superior tank maintenance and husbandry techniques and practices. In view of these findings, we have to accept this as a fact. Fortunately the explanation is a lot simpler than one actually thinks. The remedies are not difficult to implement, either, as we shall see.

The conditions that could lead to those outbreaks are really quite simple, when one thinks about it for a while and make a lot of sense from a chemistry and nutrient availability standpoint.

Phosphates that are bound in an insoluble form are, therefore, not available to algae. But can and will go into solution because of pH fluctuations in certain areas of the aquarium, areas where much lower pH exists or develops than the actual pH of the aquarium. This is due to nothing more than basic chemistry principles, but principles we may have overlooked up to now. You may recall, though, that in books it is often stressed that rocks should be regularly cleaned off and that any precipitates should be removed. The recommendations had to do mostly with removing organic material that may otherwise decompose. It turns out that these regular cleanings had an additional benefit, removing insoluble, phosphate based compounds, thus preventing them from fitting into the scenario described here.

When pH drops in those areas of the aquarium, these insoluble compounds break up with the result that orthophosphate goes back into solution, giving rise to the sudden appearance of micro algae growth, a growth that was totally unexpected and unpredictable given the tank's water quality conditions.

As indicated, this falling pH syndrome occurs mainly in two types of areas in the aquarium: in the substrate and in the crevices in the live rock. Pollutants may build up in those areas and create conditions favorable for the pH to drop quite a bit (even though the drop is very local and does not spread to the rest of the aquarium). These localized drops in the pH level in the areas mentioned dissolve the phosphate compounds that are present there, phosphate compounds that were previously inert and now no longer are. This process puts orthophosphate back into the water. If this scenario occurs in enough areas of the aquarium, enough phosphate may, and will, re-dissolve for micro algae to suddenly start reappearing in the tank. Remember, it does not take a lot of phosphate for micro algae to grow. Levels as low as 0.05 ppm can bring about outbreaks that then need to be eradicated.

Strong current in the aquarium, cleaning the rock, especially the crevices in those rocks, general maintenance and husbandry all work toward eliminating this situation from occurring. The continuous use of phosphate- and silicate removing compounds will certainly help as well. The silicate removing compounds prevent the reappearance of diatoms (brown algae growth). Changing compounds frequently enough is the key to getting them to adsorb any phosphates and silicates that may developing in this manner in your tank.

The products mentioned should be changed at the slightest increase of phosphates in the tank or at the slightest appearance of tiny hairy or stringy filaments on the glass or acrylic panes of the aquarium. Most hobbyists, unfortunately, forget that these compounds do not last forever. The load in the tank, the type of filtration used, the amount fed, and the maintenance schedule you adhere to all contribute to either lengthening or shortening the life of these products. Test regularly and inspect your tank often. If you see any alga growth, even if it is very minimal, change the compounds immediately.

Cleaning the rock in the tank is not complicated and can be done while it's in the tank or by removing it and doing so externally.

Cleaning the live rock while it is in the aquarium.

Using a length of flexible hose of approximately half inch inside diameter, create a siphon that leads to a bucket or a vat placed on the floor. Move with the hose from rock to rock and siphon off whatever detritus will come loose. Be careful not to suck any animals into the hose. To greatly reduce the amount of water you are removing, pinch the hose closed when you move from one area to another. Siphon out whatever lies on the bottom as well. Try to siphon between, behind and underneath the rocks also. This is not easy but, with a little practice, you will be amazed at how much dirt and detritus you actually remove from the tank. Watch the bucket or vat and empty when necessary. Keep siphoning until you see no more dirt or detritus.

Since a good amount of water will be missing from the tank you will need to top off the aquarium. The water you use to do so should, ideally, have been prepared the day before so it time to age and all chemical reactions that need to take place have done so. Newly prepared saltwater added immediately to a tank creates stress due to the chemical reactions between the dry salt and components and the water. It takes from 18 to 24 hours for a batch of saltwater to stabilize itself. Additionally, if chlorine is present this process will eliminate it through simple aeration of the new saltwater mixture. There is no need to add dechlorinators to the water.

Cleaning the rock outside the aquarium.

- Have two buckets or vats filled with saltwater ready.

- Have towels around

- Place the buckets on a water resistant material [e.g. Plastic sheet]

- Take one rock at a time. Place it in the first bucket and swish it around holding it firmly with your hand. As you do this the dirt that is present on the rock will come loose and mix with the - Now rinse the rock in the second bucket and then place it in the tank or in a holding vat.

- Do this with all the live rock in your tank [ or as much as you can ].

- Before replacing the rock in the tank itself, give it a good cleaning using a powerheads output to rinse off the rocks and all detritus. This will greatly improve the water quality.

Conclusion:

Micro algae can reappear when phosphate compounds re dissolve in the water, especially if this occurs in several areas at the same time. We have seen that a low PH in those areas is the cause.

To avoid this from happening you should ensure good strong current inside the tank, and clean the aquarium and the live rock regularly. Additionally, about every 6 months you should really give the tank a complete clean out to remove whatever precipitated phosphate compound may be present.

[wasp]

Good article Tang!

[lduncan]

WOW a whole article on phosphate without a single mention of bacteria

While I can see the general gist of the article, there are a few inaccuracies/oversights in the details.

• 0.04ppm is not extremely low. It's actually several orders of magnitude higher than what would be considered extremely low in terms of corals needs.

• Any phosphate with is precipitated with kalk is far from inert. It's still available to bacteria, and they will happily use it. What it does do is become undetectable by test kits (which only measure orthophosphate). This can give the illusion of phosphates being lowered.

• There seems to be a tone that this precipitated phosphate is released back into the water through purely chemical means. What's happening is that bacteria are the ones which remobilise this precipitated phosphate. One of the methods they can use is to create micro-environments, where pH may be lowered significantly within a biofilm.

Layton

[rossco]

I just wanna have a tank with pretty coloured fishies and things in it...! :lol:

[chimera]

0.04ppm is not extremely low

i believe to correctly quote what was stated above, it said < 0.04, thats less 0.04 as in 0.03, 0.02, 0.01, 0.000005, 0.0... etc

[jetskisteve]

mines lower ay wasp

[wasp]

True. Having tested quite a few tanks with proper equipment, not a hobby kit, it is unusual to find a tank lower than 0.04.

However, Steves is many "orders of magnitude" lower than that .

Most hobby kits though will say a tank is 0.00 even sometimes when there is a fair bit of phosphate.

[wasp]

Also, I didn't really see the article as an exhaustive study on phosphate in an aquarium, covering all aspects including the role of bacteria.

But indirectly it did touch on the role of bacteria as the low pH in localised areas that it discusses, is caused by bacteria. The author just did not feel the need to delve into that, which is good keeps to the main thrust and avoids looking like he is trying to blind people with "science".

But a good article nonetheless.

Oversights? No. it does not claim to be exhaustive.

Innaccuracies? Again I would beg to differ it was informative & useful.

[lduncan]

True. Having tested quite a few tanks with proper equipment, not a hobby kit, it is unusual to find a tank lower than 0.04.

However, Steves is many "orders of magnitude" lower than that .

Most hobby kits though will say a tank is 0.00 even sometimes when there is a fair bit of phosphate.

Hanna meters aren't proper equipment. :lol: You need to spend a few 10's of thousands more for proper equipment. ;-)

i believe to correctly quote what was stated above, it said < 0.04, thats less 0.04 as in 0.03, 0.02, 0.01, 0.000005, 0.0... etc

0.03 ppm isn't extremely low, so saying phosphate levels < 0.04 are extremely low, isn't even close to being correct. By that logic, I could say that phosphate levels < 1,000 ppm are extremely low, but does that make sense? Not to me it doesn't

Also, I didn't really see the article as an exhaustive study on phosphate in an aquarium, covering all aspects including the role of bacteria.

But indirectly it did touch on the role of bacteria as the low pH in localised areas that it discusses, is caused by bacteria.

Kind of important to at least mention that this is actually caused by bacteria. He didn't even write the word. It seems strange that you wouldn't. Saying it's just from localised low pH makes it seem like you may have some control over it happening, but you don't really.

Having said that it's on the right track.

Layton

[chimera]

0.03 ppm isn't extremely low, so saying phosphate levels < 0.04 are extremely low, isn't even close to being correct. By that logic, I could say that phosphate levels < 1,000 ppm are extremely low, but does that make sense? Not to me it doesn't

best you buy that 10's of thousands of dollars test equipment then

[lduncan]

What for?

[wasp]

Cos none of us will be!

But dude, if nothing but the best will do for you, you go!

[chimera]

because with out it you aint gonna know exactly what your phosphate level is. so, do what most of us do and get an approximation and judge the amount of phosphate on how well your corals are doing

[wasp]

so, do what most of us do and get an approximation and judge the amount of phosphate on how well your corals are doing

Good point. In fact I think some of the bio indicators are actually quite useful. In the case of phosphate, the "how often I clean the front glass" test is a real useful indicator, IMO probably more practical value than using a hobby test kit.

[lduncan]

that's true. Test kits (including the Hanna Meter) can never tell you how good your phosphate level is. It can only tell you how bad it is.

Wasp was implying that his "proper equipment" (the hanna meter) is somehow more useful than a test kit.

The fact is the Hanna meter is no more useful than a "hobby kit" I've said it, Hanna themselves say it, even "experts" have said it.

To call a Hanna meter "proper equipment" relative to normal test kits is not exactly fair.

I'm not saying that you need to know what your phosphate level is, it's not practical. Just know that these test kits / meters aren't even in the ball park for testing extremely low levels of phosphorous. For a start they don't even cover all forms of phosphate.

[lduncan]

In fact I think some of the bio indicators are actually quite useful... IMO probably more practical value than using a hobby test kit.

Exactly. Unfortunately that's all you really have to go on, test kits are effectively useless for letting you know how good your phosphate levels are. You've got no choice but to look at indicators in the tank. The alternative "proper" testing is just not practical.

[wasp]

Wasp was implying that his "proper equipment" (the hanna meter) is somehow more useful than a test kit.

The fact is the Hanna meter is no more useful than a "hobby kit" I've said it, Hanna themselves say it, even "experts" have said it.

Yes that's exactly what I was implying. It's a fact. Why? Cos the Hanna will find phosphate where a hobby kit cannot detect any.

Come back when you have personally used / seen one.

"Hanna themselves say it" Please show me the quote.

"experts" say it. Now let me guess, you are the "expert" right?

Also, I'm not really sure why you have this fixation about attacking the Hanna colorimeter, it is a recurring theme with you.

Have you ever used one?

Have you even seen one?

[wasp]

The alternative "proper" testing is just not practical.

You mean the one costing tens of thousands? I will confess that I did again wonder what planet you were on. :lol:

Maybe the Hanna is more "practical" after all .

[lduncan]

Yes that's exactly what I was implying. It's a fact.

Come back when you have personally used / seen one.

Can you backup this "fact"? Using one, doesn't make it more accurate than the manufacturer say's it is, nor does seeing one.

"Hanna themselves say it" Please show me the quote.

Accuracy +/- 0.04 mg/L +/- 4% of reading +/- 0.01 mg/L electrical noise.

It uses exactly the same chemical reactions as Salifert (and virtually every other brand) phosphate test kit.

"experts" say it. Now let me guess, you are the "expert" right?

No, not me. There was an article in ReefKeeping recently which talked about meters, resolution, and accuracy, and how to interpret the readings you get from them properly.

Also, I'm not really sure why you have this fixation about attacking the Hanna colorimeter, it is a recurring theme with you.

Have you ever used one?

Have you even seen one?

I don't know what makes you think they are more useful than a standard hobby test kit?

I don't have to use one. I don't have to see one. All i have to do is read the manufacturers specs, and know how it works to have an opinion on it.

I'm not attacking it. Just making an observation on how useful it is relative to other methods.

The fact is, that it's no more useful than a standard test kit. We've been through this before. Just because you think it feels more accurate, it doesn't actually make it more accurate.

Layton

[wasp]

The fact is the Hanna meter is no more useful than a "hobby kit" I've said it, Hanna themselves say it.

The fact is Hanna did NOT say their meter "is no more useful than a hobby kit".

They said it is this accurate - Accuracy +/- 0.04 mg/L +/- 4% of reading +/- 0.01 mg/L electrical noise.

There have been blind tests run on hobby kits to find out how accurately people can interpret the colours. The results people get interpreting the colours on their hobby kits are WAY less accurate than the figures Hanna give as to the accuracy of their colorimeter.

Sorry Layton, for you to say they said their colorimeter "is no more useful than a hobby kit" is well, I might as well say it, just plain untrue.

They did not say it.

You say you are not attacking the Hanna. But when you show an obvious bias by making things up, you clearly have an agenda.

Not that it affects me, I use a Hanna and KNOW how good it is, when I first got it I had 2 other brands of kits and was able to run comparisons. Pity you never have. Just don't like seeing other people being given this misinformation.

I still don't know why you feel this need to attack the Hanna in this type of way, even having to make up your "facts" to do so. I suspect you keep attacking the Hanna, simply because I have one.

[wasp]

Also, for anyone interested in Hanna colorimeters here is a link to a site selling them http://www.hannainst.co.uk/acatalog/Mul ... eterH.html

Hanna supply a range of testing equipment for use in soil testing, hospitals, laboratories, wastewater etc. Not just aquarium.

[lduncan]

The fact is Hanna did NOT say their meter "is no more useful than a hobby kit".

They said it is this accurate - Accuracy +/- 0.04 mg/L +/- 4% of reading +/- 0.01 mg/L electrical noise.

There have been blind tests run on hobby kits to find out how accurately people can interpret the colours. The results people get interpreting the colours on their hobby kits are WAY less accurate than the figures Hanna give as to the accuracy of their colorimeter.

So... what were the results. Provide some info to back that up.

Sorry Layton, for you to say they said their colorimeter "is no more useful than a hobby kit" is well, I might as well say it, just plain untrue.

They did not say it.

Their specifications say it.

You say you are not attacking the Hanna. But when you show an obvious bias by making things up, you clearly have an agenda.

I'm not making things up at all. What possible agenda would I have?

Not that it affects me, I use a Hanna and KNOW how good it is, when I first got it I had 2 other brands of kits and was able to run comparisons. Pity you never have.

How did you test them?

I still don't know why you feel this need to attack the Hanna in this type of way, even having to make up your "facts" to do so. I suspect you keep attacking the Hanna, simply because I have one.

I'm not attacking Hanna. I'm simply saying that using a Hanna meter gives you no extra information than a standard test kit. It's no more useful than a standard kit.

[JDM]

The results people get interpreting the colours on their hobby kits are WAY less accurate than the figures Hanna give as to the accuracy of their colorimeter.

i have this problem every time i test, which color is it? i often invite anyone at my house to have a look at the test and see what there perception of the color is. this sounds like a useful tool to me, defenatly something i will be looking into getting.

thanks wasp.

[lduncan]

The best possible reading you can get from a hanna meter is 0.00 right?

That means that the phosphate level is anywhere between 0.00 and 0.05ppm right?

So what does this tell you? Well not much. It could mean your phosphate levels are good, or it could mean you're phosphate levels are extremely high (0.05 is extremely high as far as corals are concerned). You have no way of knowing which it is.

So for all intents and purposes this reading is useless. That's why you have to look at indicators within the tank to get an idea of how good your phosphate levels are.

Compare this with a normal test kit can you tell the difference between the 0.05 and 0.00? (in low range)? Same deal, you could probably say that phosphate levels are between 0.00 and 0.05. Again this isn't particularly useful. Back to bioindicators.

So I want to know how the Hanna meter provides any more useful information than a standard kit? It's not.

Layton

[wasp]

No you still got it wrong Layton.

I have run my own comparitive tests, in actual practise the results come in much better than that.

I very much suspect you have never used one.