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Hydrochloric acid (HCl) to lower pH


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<H1>Hydrochloric acid (HCl) to lower pH</H1><DIV id=Qtextbox><P><STRONG>Author: THERMOFISH</STRONG><BR><BR>

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DO you think it would be ok to use HCl to lower the pH of a tank that has no fish in it yet. 'pH down' is just so damn exspensive for just a little sodium phosphate and i can get HCl free from work.

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I dont see why diluted HCl wouldnt be ok.

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Has anyone had any experience with using HCl ?

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otherwise does anyone supply Sodium phosphate at an intelligent price ?

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cheers,

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thomas.

<p></P></DIV><H2>Replies »</H2><DIV id=Atextbox><P><STRONG>Author: Willy wombat</STRONG><BR><BR>I would be very careful using HCl in your tank, even without fish. I have known people who have tried using it in aquaculture situations and they lost fish.

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Such a strong acid should never be used in a situation where fish are already in the tank, as it has the potential to move the PH a long way and will shock the poor buggers. But as there are no fish in the tank, you may get away with using a VERY dilute solution. Also please remember that you are introducing Cl- ions into the tank with you H+ ions. Shouldnt be a problem for african cichlids.

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Cheers

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WW

<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: Craig Douglas</STRONG><BR><BR>If HCl is pure or close it has to be the right thing to use to lower Ph. I agree the dilution must be correct. I believe the problem with using this stuff is the impurities the commercially available stuff has in it. Phosphoric acid is probably a much safer choice.

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Craig.

<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: approximate</STRONG><BR><BR>Thermofish, I think that's a great idea. Please try using HCL on your tank and let us know how you went.

<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: MagicaDiSpell</STRONG><BR><BR>Hmmm, my chemistry might be a bit rusty, but.... HCl is a very corrosive inorganic acid and as such probably not really suited for aquarium applications. Even if you don't have fish in the tank yet, you will probably harm the bacteria in your filter.

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I am assuming that you want to lower the pH because either your tap water is more or less hard and alkaline. Instead of adding the - hidiously expensive - pH down, I would suggest adding peatmoss or Sera Peat Granules to your tank. I have done that and it has softened my water as well as reduced the pH. I am not sure how much the peat granules cost these days, but they last a while and are much saver than HCl.

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In the end, we will conserve only what we love, We will love only what we understand, And we will understand only what we are taught. (Baba Dioum, African Biologist)

THERMOFISH

<br></P></DIV><DIV id=Atextbox><P><STRONG>Author: THERMOFISH</STRONG><BR><BR>

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I work in a pathology lab so the HCl we use is very dilute, still i decided not to use it because of the chloride ions i'd be adding, i finally found a little bit of tri-sodium phosphate up the back of a cupboard which did the trick.

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MagicaDispell, thanks for the tip, it's bit funny, my tap water is spot on pH 7. But when i set up my new tank the pH was over 8, i think it might have been the gravel or something.

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My filter (2217) is second hand, it has what looks like a bag crushed coral in it, that will raise pH?, if i cant find peat what should i replace it with ?

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I have americans by the way.

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<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: c2105208</STRONG><BR><BR>The thing to be careful with adding phosphate-related products is algal blooms.... You can get major problems within a matter of a few days even with low light levels.

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But then again, there's disadvantages and advantages to most products (particularly inexpensive methods).

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HCl not recommended due to Cl- ions. We're trying to get rid of them in the initial water aging processes (though in different forms yes), not add more.

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Cheers,

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Adam

<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: Willy wombat</STRONG><BR><BR>c2105...

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Im not quite sure about the comment you just made about the Cl- (chloride) ions.

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The major problem that i saw with the Cl- ions was not that they contained chlorine like in tap water (yes harmful to fishes, but present in the form of HOCl called hypochlorous acid, much different to Cl-)

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Rather, i was more concerned with the addition of a large amount of Cl- ions being potentially problematic due to an effect on the osmoregulation of the fish.

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(Osmoregulation is how fish balance the level of "salts" in their blood.) You see salts (or ions) can travel across the thin skin barrier between the gills of a fish and the water on the outside quite readily.

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Think of when you add table salt to water (NaCl is Sodium and Chloride ions), which becomes sodium ions (Na+) and Chloride ions (Cl-) when it dissolves into the water. Too many chloride ions in the water for some fish species will lead to problems. Not being an expert on the American cichlids i am not sure how they would handle it? What species are you planing on keeping Thermo?

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Hope that made sense, it is so hard to explain about chemistry and not put people to sleep. Hope you would all agree that it is important to understand the basics when keeping an aquarium though!

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Cheers

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WW

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<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: c2105208</STRONG><BR><BR>WW think that whole biological aspect of osmo-regulators vs osmo-conformers is a bit beyond the scope of most people here. Whislt I study it in depth at uni, as well as chemistry particularly referring to aquatic environments (see my profile if you wish) but it's complex (as you would seem to know).

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I'm aware that Cl comes in many forms.

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<DIV id=quote>Quote:(though in different forms yes)</DIV><BR><BR>

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Also beyond the scope of most people here chemistry-wise.

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My basic message that I attempted to get across was more to do with adding a harsh pure chemical. And by the way, HCl added direct to aquariums does cause problems with fish. I have numerous reports lying around somewhere in the deep dark depths of my filing cabinets which testify to all of that, and that overdoses of Cl- ions, whether in acidic HCl- form or the hypochlorous - chlorine or chloramine either one, can all be detrimental. Cl is not something you want to mess with in an aquarium in general - I'd hope with your apparent background that you'd agree and see that...

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Cheers

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Adam

<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: Willy wombat</STRONG><BR><BR>C21...

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Just making a clarification. Certainly not insulting your inteligence!

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I studied aquatic science and aquaculture (and alcoholture) at uni, so sometimes i go into a little bit too much detail about various things. I think that some people can generally follow what im talking about, but the masses seem to stare back blankly.... (shame) (Also, not a criticism of the masses)

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Cheers WW

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PS: Osmoregulator - animal that controls the level of salt in its system (such as fish) using its kidneys and other organs

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Osmoconformer - animal that cannot control the level of salt in its internal fluids (such as an oyster), and will have what ever osmolality that the outside environment has.

<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: THERMOFISH</STRONG><BR><BR>

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Exactly why a dropped the HCl idea.

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I studied Biomedical science at uni so im with ya.

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it was worth discussing though.

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<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: MagicaDiSpell</STRONG><BR><BR>Thermofish,

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The shellgrit will definitely raise the pH, it acts as a buffer and buffers the water at about 7.6. For aquaria with fish that will tolerate a pH of 7.6 and moderate hardness, I would always recommend including a bag of shellgrit in the filter, because it prevents pH crashes and also provides a source of carbon necessary for the growth of bacteria.

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Hmmm, if you can't find the sera granules, let me think. I have heard of people using the gardening-type peat for fishtanks. I would expect that to be a bit more messy than the granules, but it should work, as long as you keep it in a fine mesh, like a nylon sock or something.

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If you do decide to go with gardening peat, make sure you get the one that is based on sphagnum moss (in biological terms really the only peat moss, but the gardening industry decided to call something else peat as well, and it is cr....., even for gardening I find). And you will probably have to buy a small bale of it.

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Good luck, keep us up to date. And can I say, I have really enjoyed this biochemical excursion. Adam, yes it may be beyond many on this board, but there are lots of us that can follow and love it too.

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In the end, we will conserve only what we love, We will love only what we understand, And we will understand only what we are taught. (Baba Dioum, African Biologist)

THERMOFISH

<br></P></DIV><DIV id=Atextbox><P><STRONG>Author: THERMOFISH</STRONG><BR><BR>

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Cheers MagicaDispell,

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i think i might give the c... sphagnum moss a miss and have a good look around for the sera granules, im sure they cant be that hard to find .

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Thank again for all the help.

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Let you know how it all goes.

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<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: YeW2001</STRONG><BR><BR>Hi -

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As others have said - don't.

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On the last point... be aware that sphagnum moss and peat moss are different things.

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Sphagnum is generally living (or very recently so) moss - while peat moss is broken down organic matter (including Sphagnum and other mosses, sedges etc).

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-- YeW</P></DIV><DIV id=Atextbox><P><STRONG>Author: Craig Douglas</STRONG><BR><BR>Is the Cl- ion from NaCl different either chemically or electrically for the Cl- ion from HCl ? If not and used correctly I still cannot see why HCl should not be a suitable acid for aquarium use assuming chemical purity ?

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Craig.

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<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: c2105208</STRONG><BR><BR>No worries WW....

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Just to add to your little definition, as a generalisation most bony fish in fresh and salt water are osmoregulators, sharks tend to be osmoconformers. And, for anyone that's interested - little brine shrimp are osmoregulators whilst other shrimp, crabs etc tend to be osmoconformers. Hence why brine shrimp can live in the salt lakes where the salinity is up to 2-3x the salinity of sea water, and other species of shrimps cannot. Brackish water fish have mechanisms whereby they modify their internal structures as well as gill structures in order to adapt to the salt concentrations. It is believed at this time that most species switch between osmoconforming and osmoregulating depending on the salt ion concentration (there is a species of shark currently under research for doing exactly this at the moment - switching from completely marine to completely freshwater estuarine habitats - sorry the species name escapes me a the moment...). For others out there interested

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Funny enough, a few weeks back some rather (un?)lucky people in the chat room got a lovely big talk on the osmoconformer/regulator thing whilst I was in there. Funny it comes up all of a sudden so soon when we'd almost not heard it on here before

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Craig: The short answer to the question you ask is that yes they're essentially the same ion - the electron configurations are essentially the same. However there is a bigger biological picture here. For illustrative purposes - one doesn't actually add NaCl to the aquarium (except for SW tanks) would they? Not under normal circumstances. Therefore consider the effect of adding HCl? Sure, small concentrations perhaps but read on for a little example... As we know (and if we didn't, then we now do), pH is measured on a log scale. Assuming that the individual is adding HCl because it's a more concentrated direct way of lowering pH, and perhaps want to lower it a significant amount. For example say they need to lower the pH from say, 8.0 to 7.0. This represents a tenfold increase in hydrogen ion concentration, as well as (since in HCl there's a 1:1 ratio H+:Cl-) a tenfold increase in Cl- ion concentration (clearly this depends on how much Cl- there was in the start though, though fresh water has minute amounts of Cl- ions normally). Looking (almost too) simply on the matter, and looking at only the Cl- ion increase, it's like having ten times the salinity in a salt tank to get that same amount of Cl- ions. From where I stand, that in itself has to be a bit concerning when you consider the magnitude of the concentration increases, and hence why WW and I have had this little stint on osmoregulating and osmoconforming - and as WW pointed out, that the fish would have to cope with the increased ion concentrations. Additionally, other salt ion concentrations and biological factors pull the pH swing of H+/OH- ions out of balance (in short, increase the pH over time perhaps), therefore reducing effectively the H+ concentration. Granted most of the time the pH only lowers further due to the Urea produced in the fish, along with other factors, but sometimes the pH can rise... So if someone went to 'balance' the pH again with HCl, they'd be adding more Cl- ions on top of what's already there anyway in the process. I've almost over simplified the chemistry behind this, a tank is not a test tube and has a much wider mix of salts and other compounds which are interacting and creating a much more complicated model

but you get my drift anyway....

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Cheers,

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Adam

<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: Mr M00se</STRONG><BR><BR>Thanks Adam. As I as sure you know we all add CaCl or KCl to up Gh therefore increasing Cl- ions. I agree it would be better to add nothing but at times an adjustment in Ph is neccessary. I just thought that HCl in appropriate dilutions would be suitable, more so than say Sodium biphosphate which adds two undesirable ions?

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Craig.

<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: c2105208</STRONG><BR><BR>Yep you're right, we do add CaCl and other Chloride compounds - however gH is not a log scale, it depends on the total concentrations. This represents a significant difference in Cl- concentrations when you're talking significant changes in pH. We don't add CaCl or other chloride compounds on that inverse log scale!

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I'm not sure what you meant completely by 'appropriate dilutions'. See, the dilutions of HCl are irrelevant really, it's the total amount of ions that are added to the water which cause the pH drop. If you have 1M solution (very dilute HCl) you will need 10x more of it to create the same pH change as 10M HCl solution (concentrated).

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Sodium Biphosphate is a fairly tricky compound. Typically, the salt for Sodium phosphate should be Na3PO4, meaning 3:1. Sodium biphosphate 1:2 ratio does not appear in SI data books, leading me to believe that it's the same situation as bicarbonate soda (Calcium carbonate, CaCO3, sometimes called Calcium bicarbonate). Doesn't actually have two CO3 ions but for some reason has been called bicarbonate. I may be incorrect on this, however if I'm right this would mean that it's still a 3:1 ratio. Personally I wouldn't like either Cl- or PO4 ions in my tanks. However, I personally would consider using HCl only on a planted tank with almost no fish due to PO4 ions being so incredibly irritating for algae. As you said KCl etc are added to tanks. KCl is used in planted tanks particularly for raising K+ levels - with regular water changes, Cl ions are kept relatively low. Again though there is that problem with the log scale and the sheer amount of Cl- being added with HCl compared to KCl etc.

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Other possible acids to use may be phosphoric acid (H3PO4) which is a triprotic acid - releasing 3 protons in solution and one PO4 ion. The other possible acid to use could be sulfuric acid H2SO4 which is a diprotic acid. Personally I wouldn't use either of these, I'd just buy an RO system or similar - this would take the water at least down to around 7.0 and then a smaller amount of compounds would be needed. However - generally I think it is much safer to raise pH by adding CaOH or similar than it is to lower pH since most of the pH lowering chemicals contain detrimental ions whilst the pH raising ones do not.

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In the end I believe it would come down to the individual utilizing what they have available - I am fortunate (in a way) to be on tank water so my water is very soft and around neutral pH - hence I have mostly americans, but do have some africans using suitable buffers. If I lived on town water with a higher gH and pH then I'd probably choose africans - and avoid (south) americans as this would represent more problems lowering pH. If the individual wants to keep fish that do not necessarily correspond to the resources available then that's their choice, but imo they should be aware that it may end up being more costly and that shortcuts such as adding these acids should be avoided for their detrimental side-effects.

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Cheers,

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Adam

<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: 23Skidoo</STRONG><BR><BR>Well everyones covered it here, so i'd only like to add that a few people mentioned that this thread might get a bit beyond the scope of most users, i think it's excellent that the people with the knowledge are taking the time to post it!

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Personnally i'll post anything if i'm sure i'm right. It doesn't matter to me if no-on else can understand it, thats why you search the web and figure out what it means!

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I'm a nerd from Newie too, and it's better to share the knowledge than keep it to yourself.

<p></P></DIV><DIV id=Atextbox><P><STRONG>Author: Auscanuckafishy</STRONG><BR><BR>G'day,

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I've actually wondered what the result of adding all this -Cl will be long term. I read an interesting article on marine tanks discussing the addition of NaHCO3 and CaCl2 to the tanks for the pH. The end result was an increase in salinity levels and a decrease in all other dissolved salts. Essentially all the elements were being replaced by a lot of Sodium and Chloride. The only way to counter it was to find other sources for the missing elements.... something like that anyway.

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Now in my tanks I add Calcium Chloride, Potassium Chloride, as well as a bit of Sodium Chloride, granted not in huge numbers, but I wonder what the effect is over time. Then again they've (the fish) been doing their thing for ages so I'm not too worried.

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Just a little thing to point out:

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Bicarbonate soda, is Sodium (soda) Bicarbonate (NaHCO3). The bicarbonate is -HCO3.

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Calcium Bicarbonate would look something like Ca(HCO3)2 I suppose. CaCO3 is Calcium Carbonate which shellfish and corals (and many other critters) use to make their solid structures, in other words, that's what crushed coral is mainly.

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I'm thinking that's what you meant to say anyway Adam, so not a correction, just making sure people don't get confused

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Mark

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Nowra, NSW | ICQ#6497947</P></DIV><DIV id=Atextbox><P><STRONG>Author: c2105208</STRONG><BR><BR>Ah, too much on my mind. Sorry, yes... that is what I meant to put :S

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Thanks Mark for clearing that up.

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Adam

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