cabrego
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Posts posted by cabrego
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There's a good thread on this over at RC. It covers this topic.
http://www.reefcentral.com/forums/showthread.php?t=1804518
You'll see there that the worst-case accuracy is the specification at full-scale. It is much more accurate in close but, as you've observed, you can play with the math to make it seem worse.
For example, theoretically, you could get a 0.04 ppm reading for an RO/DI sample with 0 ppm phosphate. (The meters tested at Hanna, by the way, all come up dead on accurate at 0 ppm. My example is just to show how you can play with these accuracy numbers and tell a story that's less than illuminating.) Anyways, in that case, the % error is infinite, isn't it? Who would want to buy that?
Likewise, if the sample is really at 0.01 ppm, and the measurement given is 0.05 ppm, the meter error is 400%. The point is, the meter is still pretty darn good, even though it sounds horribly inaccurate if you couch accuracy solely terms of percentage error (because of the non-zero - the +/- 0.04 part - bias error that's being accounted for in Hanna's specification).
The accuracy specification is, by the way, the same as for their more expensive meters. See http://www.hannainst.com/usa/prods2.cfm?id=030003&ProdCode=HI%2093713 to see the specification for their more expensive 93713 (low range) model. It reads, "Accuracy ±0.04 mg/L ±4% of reading."
In my opinion, it's a really nice option to have and, over the long run, more economical than chemical tests that rely on color charts (which are often incredibly difficult to read, vary under different lighting, and still suffer from inaccuracies) to give you readings.
I generally agree with everything you have stated!
It looks like the link you posted to the RC is the same as I posted, so we are on the same page so to speak!The curiousity has finally overcome me and I ordered my very own phosphate test kit from Marine Depot (there were only 4 left and i got it for 39.99), I also bought a bottle of of 100 ppm Hach Phosphate standard. The standard will be used to test the Hanna meter and it could also be used to illustrate the effectiveness of running GFO. I guess it is just part of my nature no want to know how/if things work.
Many of the marine societies are actively testing/documenting the Hanna units at meetings and social events and posting the results online, so why not us? anyway, i will keep you guys updated...
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Per the instructions I completed my water change on Monday (48 hours later) and so far it looks like all of the cyano is gone! I am very happy about that, I put my skimmer online Monday and actually tuned it on Tuesday. It is pulling the nastiest skimmate I have seen out of this skimmer. I wish my skimmate always looked like it does today-it is a different tune so hopefully it is a better tune. But I have a feeling the chemiclean has something to do with the gunk it is pulling. In any event, I think this is a success story for chemiclean!
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Again, Hanna individually tests each and every unit that leaves their facility with a test solution that is made fresh every 2 hours. This means that the unit is within the accuracy that is in its specs which are "Adaptation of Standard Method 4500-P E Accuracy 4%
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Here's a review from reef builder.
According, to their test, the portable unit was close in accuracy to the 200 dollar unit
thanks for the link. Interesting results, one thing of note is a recipe to generate a phosphate standard using on the shelf products.
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I have it and I like it. I cannot comment on the accuracy, however, as I don't have a reference solution against which to measure it. Hanna's internal tests, however, were generally favorable according to the discussion over at RC. The device is convenient and, in the long run, cheaper. The reagents last longer (they have a 3-year shelf life) and are packaged in individual doses. It's also easier to read than color charts.
In my view the value in having one of these meters is not just ease of use but it is also accuracy. If I don't have confidence in the measurement, then the meter is just giving an indication and 'normal' liquid test do a decent job of that. You don't know if you have .25 or .5 ppm, but you know you don't have 1 or 2 ppm. It would be interesting to see documentation from Hanna's testing if it public information. Just to be clear, I am not saying the product is not accurate, I am just wondering how you know if your meter is working accurately if you have one. Is there a calibration procedure with standard solutions?
Here is a link from RC that you might be talking about, posts 192 and 196 are particularly interesting. I am not sure if post 192's standard mixing methodology is accurate but his results are consistent. 196 is a comparison against the hanna photometer.
http://www.reefcentral.com/forums/showthread.php?p=16986538#post16986538
Anyone know how to mix a phosphate standard? I would be glad put together a test with someone.
We are using them in store and they are great! Hanna individually tested each unit with a standard test solution that was made fresh every 2 hours, so I would have to say they are accurate. Untill now you couldnt touch a decent P04 test kit for less than $100 (Deltec) and even that one was pretty involved, I am pleased with both the ease and accuracy of the units.
John
Glad to hear they are working well for BRK. Are these kits in stock for the masses, or do you have to be 'on the list'?
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Apparently there was a bad batch of chemiclean being distributed a few years back.
http://reefcentral.com/forums/showthread.php?t=1001972&highlight=chemiclean
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Hi,
Just wondering if anyone has actually used one of the new phophate colormeters that are for sale. I believe Hanna makes them. What are your thoughts on it? There were mixed reviews on Reef Central.
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I just added a new probe a few weeks ago and calibrated it before I set it up but maybe I will try it again.
Good idea!
Laura
To verify your probe is working correctly-just stick it in the calibration fluid (both 7 and 10) and see what it reads. It shouldn't be too much more than .05 off. I have the big bottles of the fluids and I just pour them into shot glasses as needed.
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how are you measuring the ph? I would verify reading first and work from there. Have you calibrated your probe lately?(if your using one) My ph was reading 8.3 or so for a few weeks but my calibrations was off, it was actually closer to 8.0.
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I think they are much easier to keep and grow than SPS but getting the optimal coloration is something I have not quite figured out yet.
yeah. those are great pics with good color
what camera/lens?
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Are chalice difficult to keep? What are the requirements?
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The sarcasm went right over my head. I had bubbles up until the 3rd water change after dosing.Yes, I changed 20% water after each dose. I made extra water after the first dose, just in case. I cut the second dose in half but still went ahead with 20% water change. It hasn't come back since.
Yeah, I assume as long as I am allowing the skimmer to dump bubbles into the sump-I will have lots of micro bubbles in the display. I did not realize you were suppose to repeat doses this stuff but I guess that makes sense.
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The bubbles are normal. They will go away with the water changes.
I was being a bit sarcastic about the bubbles being a side effect
But I do have a questions for you-you mentioned it took 4 days for the chemi to work. Did you do the 20% water change after 48 hours? And dose again? Or did you just use a single dose?
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Update- last weekend I did a very large water change, close to 30 gallons, and manually removed cyano and vacuumed my thin sand bed. Over the last week the cyano showed some signs of improvement but was still significant, as expected. I am sure it would take weeks of this new routine for it to be really effective.
Because I would like to see results quicker I did the deed yesterday. I picked up chemiclean from superpetz in annandale and I went ahead and dosed my system for 90 gallons-I think that is a conservative estimate of my system volume. I turned off the UV and took the reactors off line per the instructions. I am running my skimmer without the collection cup to provide aeration. I also have a ac50 running with an air line to provide additional aeration.
So far after 24 hours most of the cyano has almost completely disappeared. As of tonight there are still a few small patches here and there but it has dramatically improved. The plan is to do a 20 gallon water change tomorrow night. As for the live stock, no signs of stress, corals show normal polyp extension. The biggest side effect I have seen so far (keep fingers crossed) is that my display is full up micro bubbles.
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the best price out there....http://cgi.ebay.com/Chemiclean-2g-Cyano-Red-Slime-Algae-Remover-Chemi-Clean-/190385069142?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item2c53d59c56
thanks for the link. i dont mind paying a few extra dollars if i can get it locally. anyone know who stocks it?
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No, I got mine on ebay. How big is you system? I'm willing to share some of mine if your system isn't too big. you can start to treat, order some and maybe get a handle on it until yours arrives.
total volume is about 120 g or so, I appreciate the offer. I don't mind buying some but it sounds like this stuff works so good that you only use it once. do you have to continually treat with it?
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anyone know of a local source for chemi clean?
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COOL. but this format is realllly confusing and not convenient! how about just setting a poll with the original thread linked...saves you work and should be convenient
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Here's my entry...
Original Superman Encrusting Montipora
Shot with:
D3000
1970's Nikon Micro Nikkor 55mm f/3.5 AI'd (Manual Exposure, Focus, etc.)
JPEG+RAw Mode
Processed in Photoshop
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Recommend Petland in fairfax for live rock, they have a good selection at a reasonable price and their location is good for you too. Good general reef products like salts, solutions, etc.
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Depending on how complicated you would like to bet- there are a number of solutions. I prefer the simplest solutions. It sounds like you have a catch can that is placed out side your sump and from your post it is probably on the room's floor. How about remove your catch can? You could also put the catch can in the sump if applicable.
You could also get into more complicated solutions like set up a float switchin your catch can that turns the skimmer off when it is triggered. I prefer simple solutions though..
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Anyone know where they sell these?
if you are talking about a standard 1/4" solenoid, I know brk use to stock these.
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How did you determine your Mg level to maintain? I used 1600-1700 with good success.
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to be perfectly honest - no ... I was so busy vacuuming and brushing and rinsing and bleaching and setting up the frag system ... well I just never focused on the fact that it had been over six weeks since I last did a water change on that system.
I see, it looks like we have something in common. I think I am going to give the natural method month or so, if I don't see improvement I will probably go with some chemiclean...I will keep you guys posted.
New Digital Phospate Test Kit
in General Discussion
Well, I ordered directly from Hach so I don't know if I can change the order. Do you think it will be difficult to use the 100 ppm standard?
I am thinking 1 ml can be measured very accurately with a syringe and 100 ml can also be measured very accurately, so 1 ml of Standard in 100 ml of RODI give 100 ml of 1 ppm Phosphate solution. I will also have a fair amount left over in case I am not confident in my measuring techniques. One of the expensive meters would be good to have for this test too, but I don't know anyone locally that owns one.
Anyone have high precision pipettes or beakers I can borrow? Else I will probably start off with the syringes we have for our medicine and other aquarium test kits. I think my Mg test kit has a 1 ml syringe.
Any flaws with my logic?