View Full Version : Phosphate Adsorber Tests
Help!
We are having some fairly intensive testing done on phosphate removers over the next couple of months. We would like to compare other media to our Ultiphos range but it's hard to do as IMO there are no good tests out there.
There's no point in testing the wrong things the wrong way! So we need some input from you guys- so get your thinking caps on.
First which ones should we test? Obviously we need to have ours done but which others?
We thought: (in alphabetical order)
Antiphos Fe
Elimiphos
Phosban
Phosphate Killer
Phosphate Sponge
Rowaphos
Ultiphos Fe
Ultiphos P
Ultiphos R
(All trade marks are the property of their owners and are recognized)
Have we missed any important ones?
The tests are going to be blinded and carried out by a UKAS accredited lab. This should avoid accuracy problems or accusations of bias. The testers simply will not know what they are analyzing and their equipment and methods are independently validated. We will publish both our conclusions AND the experimental protocols AND the raw data.
Does this sound OK?
The basic methodology is the generation of an adsorption isotherm by using different known amounts of media to adsorb phosphate from a known solution and measuring what is left. A simple mass balance then gives you the media phosphate loading.
Our criticisms of other studies have led us to these ground rules. Have we missed any?
1/ Go straight out of the sealed pack as bought: no drying, no grinding or pre-treatment. A hobbyist wouldn't do this before using it so the test shouldn't either.
2/ Use saltwater (IO) at a typical reef keeping salinity, pH and temperature. Not freshwater, not a salt specially blended for the experiment, or with an adjusted pH, or at an odd temperature.
3/ Use a sensible phosphate concentration. There is little point in knowing the binding capacity at 100ppm phosphate. We thought 0.5ppm. What do you guys think? Too high? Too low?
4/ We think we should express the results in 4 ways:
a) Grams phosphate bound per volume of media.
b ) Grams phosphate bound per kg of media (out of the pack).
c) Grams phosphate bound per kg of media (corrected for dry weight).
d) Grams phosphate bound per £1 worth of media at RRP/SRP.
5/ A test to show the final equilibrium level of phosphate by adding a good excess of media and measuring the finishing phosphate level (hopefully in ppb).
6/ ICP-MS analysis of the saltwater exposed to each media to check for any release of metals from the media. This is a potential concern with Al based products and a possibility with some iron based ones too.
Anything we have missed?
Apologies for the boring post :thanx:
Andrew (UA)
Looks pretty comprehensive to me!
Thanks for the continued support of the hobby. I just wish you were closed! (sorry I meant closer!!)
Kev
Found Nemo, what now?
05-10-05, 19:34
Tee Hee!
Kev,
did you mean to say "closer" or this a business rivalry I've missed?
:blink:
How will you set up the media to absorb the phosphate, will the media just be put into a bag and then into a container of water or will it be have water runnign through it like we use it?
A couple of q's
Is there any way to test to see if the effectiveness of the media when run this way compared to being run in a fluidiser?
Is there anyway to test is the media still works after so many days, i.e to see if the coating of algae it gets from beign in the water effects its ability to remove phosphate?
Sounds good ! :thumbsup:
I agree with Maestro, how long will it last for our money ?? ........perhaps difficult to quantify ?
If we had say 5 ppm using X amount of product reduced to X ppm that lasted for X amount of time ?
I for one would be very interested in that ! :thumbsup:
chris allsop
05-10-05, 20:28
i wouldent mind knowing which one is the best!!
Sounds great. :)
Especially testing for any leaching of "nasties".
The only other thing I can think of right now is whether the adsorbers remove measurable amounts of carbonate/bicarbonate from the water. We know that there is probably some effect, it would be nice to know if this is significant for our purposes. Possibly as part of 5, where phosphates are depleted and the media is plentiful.
:)
kim
(ps perhaps Kev is under control of the Great Evil One ? )
Wow :)
Would the sample water be from a running system and as such include some organics, bacteria, nitrate e.t.c ? or a fresh sterile mix ?
I'm sure you already have, but worth rereading the below to pick up on aspects
http://www.reefkeeping.com/issues/2004-11/rhf/index.php
This would be very interesting - good on yer for sponsoring this.
Couple of suggestions. Given concerns that have been expressed about sudden changes in phosphate levels, I wonder whether we could get an indication of how rapidly they absord a given amount of phosphate? I'm thinking that even if Rowaphos and Phosphate Killer (just for example) had otherwise identical binding capacities the fact that one might bind 1mg of phosphate in a day whilst the other took a week to do the samemight be important.
Second, I wondered about including the Rowaphos version for ponds in the test. I know they say it isn't as effective in saltwater, but depending on the pricing it might still offer vfm.
Keith
you specify that the test water is going to be typical reefing conditions, but you didnt mention the volume of water that the phosphate is being extracted from, a half kilo of media will have no problems removing a phosphate level of 5ppm from a 2 gallon jug, but it might struggle with a 1000 gallons
would it not be beneficial to run a higher phosphate level? if some of the phosphate removers are able to pull all the phosphate out of the water how are you going to know their true absorbtion capacity if there is no more phosphate left in the water?
please bear in mind that its late and i may be typing a load of b*llocks :thumbsup:
Good idea....., id really like to see how that cheap stuff hagen make available....think its called 'green away' or something similiar....i had a brief look at it and it loooks like an iron based media like many of the others..
Paul.
i can see some very unhappy makers soon
Maestro,
We need to avoid problems with the different flow characteristics of the different medias and ensure that all the media is exposed to the test solution. About the only way to do this is to dump it into the test solution and put it on a shaker table. After the test the solution would be filtered to remove the media. Putting it in bags and so on is going to add too many unknowns into the experiment. You can be pretty sure that the worst performing medias manufacturers will try to poke holes in this.
This method would be pretty much akin to running the media in a slow fluidiser.
Yes we would like to do some long term testing later on. To be fair I doubt that we would see much algal growth or surface blinding with such a soft media bashing about in a fluidized reactor. But in a media bag this could be a concern, we are having some testing done on what coats the media surface when it's used in a tank. They zap the surface with a laser to vaporise the top layer and feed the resulting gas into a mass spec. which tells you what was on the surface. My best guess so far is lime-scale, but I could well be proved wrong.
Col,
Yes that's the idea once we have constructed an adsorption isotherm for each media you can do this. Basically you bung in your starting phosphate level and your water volume, set your target level and the calculation will tell you how much media you need to use. The only snag is that the calculation will only be fully accurate at the pH, temperature, and salinity of the original test. Hence our worry about using freshwater phosphate loadings to make predictions about saltwater loadings or running tests at "odd" pH's and temperatures.
Kim,
Good point yes we could add in bicarbonate depletion at part 5 with very little effort. Should be well worth doing.
Reefclown,
It would have to be "sterile" I'm afraid. Anything else would lead to problems, we need the experiment to be 100% reproducible. Water from "a running system" is just too vague. It would leave us wide open to suggestions of cheating. For example, by adding certain legitimate reef supplements to the "running system" we could very easily swing the test results in a direction of our choosing ;) But yes we will be doing this as well just to try and spot any huge differences.
Yes read that one, RH-F seems to have about as much "respect" for the current studies as we do :lol:
Jacksok,
As to speed we have already done some work on this and within reason it seems to depend upon HOW the media is used and not upon WHICH media you are using. Very roughly, bunging it in a media bag is very slow, fluidizing it at a high flow rate is very fast. The overall amounts removed with both methods are about the same, assuming the stuff in the bag doesn't "set". So for an initial reduction in phosphates for a first time user the "worst" thing to do is use loads of media in a high flow fluidized filter. Their "best" bet would be to use repeated small amounts of media in a bag in an area of moderate flow.
Yes the pond stuff does seem to come in bigger (cheaper) packs, worth a look.
weegaz22,
The volume of water isn't really that important, it's the ratio of media to water. As it happens we will be using 200ml. The reason being it fits nicely into a 250ml flask and leaves enough room to stop it sloshing all over the place on the shaker table ;).
Spot on, we need to get the amount of media used to be "not quite enough". As you say showing that every brand made is able to remove "all" the phosphate from the a weak solution of phosphate would be a waste of a few £thousand.
High phosphate level: That's cheating! If we use a very high level of phosphate it's too easy for the media to do its job. Imagine it this way. We take you and a mate to a football pitch. You each get a wheelbarrow. On one half of the pitch we scatter exactly one wheelbarrrow-full of tenners. On the other half of the pitch we scatter 1000 wheelbarrow-fulls of tenners. If you can fill your wheelbarrow in under a minute you get to keep the money. Which half of the pitch would you pick?
But you are right there are studies that have been done in this way. The point being it pretty much guarantees a "good" result.
Wiseowl,
Right you are I'll track some down and have a look.
treeboa,
"i can see some very unhappy makers soon" Why? Surely their media works far better than ours does :evil:
Anybody have any thoughts as to the level of phosphate we should use? What do most reef tanks run at in the real world?
Andrew (UA)
Hi Andrew, after seeing this thread I felt I would like to say two things in way of commending what you are doing
1. It shows a confidence in your product when so many manufactures take the basic, Take it or Leave it attitude, (The Zeo debate is a perfect example).
2. The fact that you are doing this in an open forum where you have no power of censorship, another fact that many could learn from if they had the courage.
I wish you all the best in your comparison tests and look foreward to seeing the resuts.
I believe a similar test is being done in the U.S. at the moment with skimmers, which I also will be eagerly awaiting the results.
Regards, Mike
simon garratt
06-10-05, 23:33
Hi andrew.
just a couple of thoughts........(its late, bare with me :D )
I take it that seeing as you are trying to emulate real world scenarios but on a smaller (lab vaible) scale, then the relative proportions ie recommended media to water sample volume would apply as well......IIRC Rowaphos is somewhere round about 250 gmms / 150 gall of tank water as a recommended dose. ie 0.41grms of media per 250ml of sample water.........?
Personnaly i would start out with a value of 0.3ppm which seems to be a pretty good average for people feeling the need to introduce media as problems start to become noticable. IMO by 0.5ppm+ youve normally got major probs and your not just fighting free PO4 levels, your also fighting locked phoshate that is realeased back as algae starves out......(thats another issue but you get my drift).
Finally, id be very interested to see the short term (immediate) effects on pH and redox that each media has at recomended levels. ( i have a hunch that this is a more pressing issue than the alledged rapid PO4 starvation theory's that are currently flying about, and being hailed as the answer to mysterious Acropora losses).
Regards and good luck with the survey.
Si. :D
Mike,
Thanks for the support :blush:
Si,
Yes that's the plan, one point on the isotherm will be at the recommended ratio of media to water. This point plus the heavy overdose of media point are where we will be looking at potential metals release, alkalinity depletion, pH, and now redox (thanks for that we hadn't thought of redox).
To be honest I doubt that we will be able to make any good predictions about the Acropora issue. The problem with GFH is that it does rather more than remove phosphate. We've potentially got pH, alk, trace element removal, iron release, small suspended solids release, organics adsorption and Lord alone knows what else going on. At the end of the day we know that GFH markedly changes the chemical soup in our tanks. So to avoid trouble the chances are we should make these changes slowly. Hence our "Initially use repeated small amounts in a bag" advice. This has got to be safer than a great load bunged in a fast flowing fluidized filter.
So that's another vote for 0.3ppm. The three front runners for starting phosphate level are 0.5ppm, 0.3ppm and 0.1ppm. Chances are that we will do 0.3ppm as this is in the middle. Doing all three would be nice but the cost is a little scary.
Andrew (UA)
kudos for doing this, most looking forward to your findings. watching this one closely :thumbsup:
I am also looking forward to the results, Andrew :thumbsup:
simon garratt
07-10-05, 11:27
Sounds good Andrew. Im very interested in the pH and redox issue as i feel (and some others have witnessed) some scary issues with these media's if used outside the recommended ranges. But it would be good to see what effects there are at normal levels. especially prevelant to those that run DSB's etc with the knock on effect of lowerd pH and lower layer dissolution rates in relation to ambiant tank pH.
Im off on one again.......... :D
I'll wait with baited breath........ :thumbsup:
Andrew,
Not sure if I can add much, as you seem to have covered most possibilities. Using a UKAS accredited lab is probably a good (if costly) move, but certainly one consistent with the transparency of what you are trying to do.
Presumably you will use several phosphate to adsorbent ratios to generate the adsorption curves, this could involve weighing very small quantities of media to achieve saturation (of the adsorption capacity) at "ordinary" phosphate concentrations. I get the feeling that you intended to do look at the total binding capacity.
Presumably you will determine dissolved (or total) phosphate in the solution both before and after exposure to the media, then calculate the mass sorbed by difference. If you do then the calculated sorbed mass may be subject to possible issues with the limit of detection of the analytical technique. Have you considered the possible situation where all available sorbents can reduce the phosphate level to less than the limit of detection of the technique, this might leave you in a situation where they all turn out to be equally good (on the basis of the test results) even if their actual performance varies.
Very interested to see if there are any releases from the media (presumably this will be inorganic analysis only, ICP-MS?) although any release of metals I would expect to be removed by skimming in a running system (although that is pure speculation.
All the best,
Dod
Originally posted by dod@Oct 11 2005, 12:04
Using a UKAS accredited lab is probably a good (if costly) move, but certainly one consistent with the transparency of what you are trying to do.
Dod,
Tell me about it-they make aquatics prices look like a 99p store! Back in the dim and distant past I must have run tens of thousands of seawater trace metal samples through AAS. If only I knew then what I know now, at £30 a sample I could have been rich. Still if the fishy thing doesn't work out....Ultimate Discount Analytical :lol:
To be honest we already know the answers, so we can select the appropriate amounts of media:phosphate to avoid getting the all encompassing zero of doom. The big problem with our answers is who would trust an analysis done by us when we sell the stuff? I certainly wouldn't.
Hence the choice between a new car and UKAS accredited lab work :o
It's very frustrating when you can do it yourself for just the cost of the consumables. But it should stop us getting our backsides sued off. IMO nobody but a fool is going to argue with a blinded UKAS accredited analysis. If they do we will have certified sub-samples archived for re-testing.
Yes inorganics for the elutables. We want to look at metals as several folks have raised this as a concern with certain iron based phosphate removers and also the obvious concern with the aluminum based removers. It will be interesting to see if these fears have any basis in fact.
Yes we are using ICP-MS, its about the only sensible way to get accurately into the low ppb range. As you say the amounts we are looking for are going to be stupidly small and we don't want it +/-50%.
Thanks for the input. The more folks we get thinking about this the less chance there is of us missing something.
It's going to be fun :cheers:
Andrew (UA)
Originally posted by uda@Oct 11 2005, 17:30
To be honest we already know the answers, so we can select the appropriate amounts of media:phosphate to avoid getting the all encompassing zero of doom.
:o
I've started drafting my rebuttle of the results - just need someone to sponsor its publication. Any ideas, anyone ?
:lol:
kim
I am really looking forward to these results. Can you give an indication of when this work will be completed?
And one last question - how are you going to present the results?
Are you just going to let the figures speak for themselves and leave us to crawl through them and reach our own conclusions, or will there be some interpretation and conclusions provided as well? And if so by whom?
Keith
Keith,
Thanks for the interest.
We reckon approx. 2 months, mainly due to the lab being very busy and me being too mean to pay for their "express" service. How much! :lol:
As to the where the results will be published. I have floated the idea with a popular fishkeeping publication-you have never seen anybody run so fast in your life :ph34r:
Consequently we will be posting a link on here, but they will be published on our website. We don't want to involve UR in any potential 'issues'. Obviously discussing on UR results which were published and hosted on another website would be perfectly OK.
As to how we will present them that's a good question. What do you think?
I had in mind to do both. In other words we would give our conclusions, I suppose written by me. We would also post the data upon which those conclusions were based, to allow others to reach their own conclusions.
Needless to say I wouldn't be daft enough to go out on a limb with a speculative conclusion whilst publishing its shaky foundations. Any conclusions we publish will be pretty black and white and erring on the side of caution and provable fact. I have no wish to be sued. So I suppose from that point of view you can trust that what we say will be correct.
Andrew (UA)
Wouldn't Marine World run an article? They seem to be into some fairly involved stuff. I'm sure that I picked up a copy in a popular Fife fishmongers a while back. :D
I sometimes get the feeling that things in print have greater credibility (although it isn't necessarially true), but the web may get far wider distribution. I take it you've already discounted publishing in Limnology and Oceanography.
Cheers,
Dod
Thanks for the reply Andrew.
I do think that providing an interpretation of the results would enhance their usefulness and accessability for many reefkeepers. And I'd trust you to write a fair summary of those results. How could you not, given the underlying evidence will be freely available, and you'd have Kim on your case if you didn't! :ph34r::D You'd just expose yourself to reputational risk and potentially undermine the validity of the results.
But I also think that the impact of those results might be enhanced if they had the public backing of someone widely known in international reefkeeping circles (ok, I mean American reefkeeping circles). Otherwise it risks being ignored or overlooked as just something by those quaint, quirky Brits, which would be a shame - I think rigorous independent testing of products can only only be of benefit to hobbyists who too often get taken for a ride. Ideally you'd get someone like RH-F perhaps, but this presents other potential problems. You can't really pay them, or whatever they say risks being presented as tainted. But would they do it for free? And could you be confident that they would be clear and not hedge their comments so much as to muddy the results?
I can understand how mags that rely on advertising revenues from these distributors and manufacturers wouldn't want to be associated with something that would threaten those revenues. Unfortunately when push comes to shove they exist to provide profits to shareholders - not offer an impartial service to readers. I assume the mag you refered to was a UK publication? Might some foreign and/or online publications be less in hock to these same advertisers?
Finally, I don't suppose you could be tempted to manage the testing of other products too? How much might it cost to run a double blind trial of Ecoaqualizers for example? Maybe the distributors could be persuaded to fund it? Or maybe enough hobbyists could be persuaded to make £1 PayPal donations to support it? Just a thought.... ;)
Regards,
Keith
BTW the hagen stuff is called 'green X'.....
Andrew, have you got the results of the tests yet?
Yes most of them are in and the rest are on their way.
Unfortunately/fortunately? It would appear that some of our answers are a little 'awkward'.
Consequently, we are being very cautious. Previous comparisons of phosphate removers have reportedly wound up in court. So we are getting yet more corroboration before we go public. This time with a BIG name for us to hide behind ;)
The best news from our current results is that we don't have to throw a tonne of UltiPhos away, apparently we backed the right horse B).
On the "clumping" front we have pretty much figured out what causes this behavior in iron based phosphate removers. Guidelines to follow, meanwhile a good tip is to keep your calcium and alkalinity in "balance". Also keep your Kalk mixer outflow well downstream of your phosphate remover.
HTH
Andrew
simon garratt
15-12-05, 17:44
The best news from our current results is that we don't have to throw a tonne of UltiPhos away, apparently we backed the right horse
FIX......FIIIIIIIIXXXXXX.....FIXXXXXXXX.........
You havent even put up the results yet and we allready know what your gonna say........... :D :D :D
Regards
Si.
rowaphos addict...........(for the moment i take it ;) )
Originally posted by uda@Dec 15 2005, 16:41
The best news from our current results is that we don't have to throw a tonne of UltiPhos away, apparently we backed the right horse B).
Pity really. I hear that Nav had already hired a truck........
:ph34r:
kim
sound good :)
Pity really. I hear that Nav had already hired a truck........
Lol, change of plan, trying to persuade Randy to hire a truck now ;), it's a long drive to India :lol:
Maybe I have missed it but did these results ever get published?
I run a Po4 remover called PhosGuard. I'd be interested in seeing if it is a poor product considdering it's very low price.
I run a Po4 remover called PhosGuard. I'd be interested in seeing if it is a poor product considering it's very low price.
As an aluminium-based adsorber, I'm not sure it's included. Many people steer clear of these because of articles like this.....not conclusive, but raises some worries:-
http://www.advancedaquarist.com/issues/july2003/chem.htm
That's not to say that ferric oxide equivalents don't also have some unconsidered effects, but people go on the information available.
kim
Marc Foord
26-04-06, 11:01
as a side note, i noticed an interesting item on the d&d website under "latest news"
http://www.deltecaquariumsolutions.com/LatestNews.htm
"
Spring 2006
Rowa receives its Patent Number from the European Patent Office for Rowaphos which officially confirms the advertising statements that the surface chemistry and adsorption capacity for phosphate of this product is unique.
So those people that believe that all iron based phosphate removers are the same may have to think again.
"
hmmmmm........
I would be interested in seeing time course data to give and indication of the rate of removal,
as a side note, i noticed an interesting item on the d&d website under "latest news"
http://www.deltecaquariumsolutions.com/LatestNews.htm
"
Spring 2006
Rowa receives its Patent Number from the European Patent Office for Rowaphos which officially confirms the advertising statements that the surface chemistry and adsorption capacity for phosphate of this product is unique.
So those people that believe that all iron based phosphate removers are the same may have to think again.
"
hmmmmm........
Yes this one attracted my attention too. But the only patent from these guys I've seen this year is DE50108587D (http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=DE50108587D&F=0&QPN=DE50108587D&OREQ=0&). It covers WD's process for making GEH/Rowa, but it's basically a continuation of a previous patent.
The odd thing is that AFAIK it doesn't talk about the surface chemistry or the adsorption capacity or indeed anything about phosphate at all:confused:. So it can't be this one?
I emailed Rowa about it weeks ago, but I got no reply. So if anyone knows the patent number they are referring to then please let me know as I would love to read it.
Andrew (UA)
Odd, I couldn't find anything and nor could an old college friend....who works at the European Patent Office !
Rowa receives its Patent Number from the European Patent Office for Rowaphos which officially confirms the advertising statements that the surface chemistry and adsorption capacity for phosphate of this product is unique.
When did the patent office start confirming advertising claims anyway ?
:D :D
kim
simon garratt
27-04-06, 08:33
Guys. Lets be very carefull with this one please. Just becouse you cant find something doesnt mean it doesnt exist an all that.......
Im sure you see where im comming from.:)
regards
Si.
As an aluminium-based adsorber, I'm not sure it's included. Many people steer clear of these because of articles like this.....not conclusive, but raises some worries:-
http://www.advancedaquarist.com/issues/july2003/chem.htm
That's not to say that ferric oxide equivalents don't also have some unconsidered effects, but people go on the information available.
kim
I've been busy with work (changing restaurant menu!!) and have'nt actually had time to sit down and read the article re: PhosGuard. I have read it now and it is very interesting to say the least. "You get what you pay for". I am looking forward to spending $50 for RoawPhos now!! I have been curious as to why my corals fluxuate between being happy and not happy. This explains it I think. THANK YOU for the link...It was a good read.
As an aluminium-based adsorber, I'm not sure it's included. Many people steer clear of these because of articles like this.....not conclusive, but raises some worries:-
http://www.advancedaquarist.com/issues/july2003/chem.htm
That's not to say that ferric oxide equivalents don't also have some unconsidered effects, but people go on the information available.
kim
Very interesting on the phos remover, but did you also notice the issues with feeding brine shrimp - very high in aluminium. Worrying?
I dont want to keep asking if this is a sensitive subject but I still haven't seen any results?
Have they been published or if not are there any plans to publish them?
Maestro,
Our testing is being repeated by the manufacturer of UltiPhos and they can publish their results. Unlike us they have a legal department and an annual turnover of several billion pounds. Beyond that I can't really comment.
Andrew (UA)
Are there any updates Andrew?
Saj,
It's out of my hands now. We sold the brand to an American aquatic distributor at the end of June. Their Glasgow office is now distributing UltiPhos in the UK. Apparently they are looking for "a global portfolio of innovative aquatic products". Sounds like fantastic fun.
I've played with their new Peltier conditioners, a very clever bit of kit that automatically holds +/- 0.2 C by cooling or heating as required. If they are a sign of things to come I think we will see plenty of "new toys" in the UK.
FWIW R-H-F on Reef Central is doing some independent phosphate remover testing and he should be publishing his results in "late summer". The ones to look at are the phosban results.
AFAIK his only public comment to date is "I've finished testing Rowaphos, and it certainly works, although not to the extent claimed on the bottle. http://www.reefcentral.com/forums/images/smilies/smile.gif".
HTH
Andrew (UA)
We sold the brand to an American aquatic distributor at the end of June.
Eeek.....now the Americans are lovely people, but awfully litigious. I just hope they treat the competition nicely.
:D :D
kim
scooby_rex
10-07-06, 11:16
litigous americans, nah never, actually an american would probably litigate someone for calling them litigious.
From my own perception (use in a running system). Phosban did bugger all, Rowaphos in small quantities changed weekly was very good. Ultiphos is up next week.
fluidised in a phosban reactor, using salifert to test, readings are low anyway worst a slight tinge phosban had no impact rowaphos instantly cleared the test result.
benribbans
25-07-06, 12:07
Watching with interest........
Im using Ultiphos at the moment, the pellet version (am I allowed to say that.....??? :p ) seems pretty good although I dont as yet have a high sensitivity test kit so be interested to see the results compared to price etc...
Ben
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